This review summarizes the relevant literature for the selection of the initial imaging in 4 clinical scenarios in patients with suspected inflammatory disease or postoperative complication of the anorectum. These clinical scenarios include suspected perianal fistula or abscess; rectovesicular or rectovaginal fistula; proctitis or pouchitis; and suspected complication following proctectomy, coloproctectomy, or colectomy with a pouch or other anastomosis. The appropriateness of imaging modalities as they apply to each clinical scenario is rated as usually appropriate, may be appropriate, and usually not appropriate to assist the selection of the most appropriate imaging modality in the corresponding clinical scenarios of anorectal disease. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Small-bowel obstruction is a common cause of abdominal pain and accounts for a significant proportion of hospital admissions. Radiologic imaging plays the key role in the diagnosis and management of small-bowel obstruction as neither patient presentation, the clinical examination, nor laboratory testing are sufficiently sensitive or specific enough to diagnose or guide management. This document focuses on the imaging evaluation of the two most commonly encountered clinical scenarios related to small-bowel obstruction: the acute presentation and the more indolent, low-grade, or intermittent presentation. This document hopes to clarify the appropriate utilization of the many imaging procedures that are available and commonly employed in these clinical settings. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Gastroesophageal reflux disease (GERD) is a common condition and impairs the quality of life for millions of patients, accounts for considerable health care spending, and is a primary risk factor for esophageal adenocarcinoma. There have been substantial advances in understanding the pathogenesis of GERD and its complications and much progress in diagnosis and management of GERD; however, these have not been comprehensively discussed in the recent radiology literature. Understanding the role of imaging in GERD and its complications is important to aid in multidisciplinary treatment of GERD. GERD results from prolonged or recurrent reflux of gastric contents into the esophagus. Common symptoms include heartburn or regurgitation. Prolonged reflux of gastric contents into the esophagus can cause erosive esophagitis. Over time, the inflammatory response related to esophagitis can lead to deposition of fibrous tissue and development of strictures. Alternatively, the esophageal mucosa can undergo metaplasia (Barrett esophagus), a precursor to dysplasia (which can lead to adenocarcinoma). Conventional barium esophagography has long been considered the primary imaging modality for the esophagus, and the fluoroscopic findings for diagnosis of GERD have been well established. Multimodality imaging has a clear role in detection and assessment of the complications of GERD, specifically reflux esophagitis and Barrett esophagus; differentiation of benign and malignant strictures; and detection, staging, and posttreatment surveillance of esophageal adenocarcinoma. Given the dramatic changes in utilization of abdominal imaging during the past 2 decades, with significantly declining volume of fluoroscopic procedures and concomitant increase in CT and MRI studies, it is crucial that modern radiologists appreciate the value of barium esophagography in the workup of GERD and recognize the key imaging features of GERD and its complications at CT and MRI.

Crohn disease is a complex, long-lasting (chronic) disorder that primarily affects the digestive system. This condition involves an abnormal immune response that causes excess inflammation. It most often affects the intestinal walls, particularly in the lower part of the small intestine (the ileum) and portions of the large intestine (the colon). However, inflammation can occur in any part of the digestive system, from the mouth to the anus. The inflamed tissues become thick and swollen, and the inner surfaces of the digestive system may develop open sores (ulcers).

This review summarizes the relevant literature for the initial imaging of patients with symptoms of dysphagia. For patients with oropharyngeal dysphagia who have an underlying attributable cause, a modified barium swallow is usually appropriate for initial imaging but for those who have unexplained dysphagia a fluoroscopic biphasic esophagram is usually appropriate. Fluoroscopic biphasic esophagram is usually appropriate for initial imaging in both immunocompetent and immunocompromised patients who have retrosternal dysphagia. For postoperative patients with dysphagia, fluoroscopic single-contrast esophagram and CT neck and chest with intravenous (IV) contrast are usually appropriate for oropharyngeal or retrosternal dysphagia occurring in the early postoperative period where water-soluble contrast is usually preferred rather than barium sulfate. In the later postoperative period (greater than 1 month), CT neck and chest with IV contrast and fluoroscopic single-contrast esophagram are usually appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

This review summarizes the relevant literature regarding imaging of suspected diverticulitis as an etiology for left lower quadrant pain, and imaging of complications of acute diverticulitis. The most common cause of left lower quadrant pain in adults is acute sigmoid or descending colonic diverticulitis. Appropriate imaging triage for patients with suspected diverticulitis should address the differential diagnostic possibilities and what information is necessary to make a definitive management decision. Patients with diverticulitis may require surgery or interventional radiology procedures because of associated complications, including abscesses, fistulas, obstruction, or perforation. As a result, there has been a trend toward greater use of imaging to confirm the diagnosis of diverticulitis, evaluate the extent of disease, and detect complications before deciding on appropriate treatment. Additionally, in the era of bundled payments and minimizing health care costs, patients with acute diverticulitis are being managed on an outpatient basis and rapid diagnostic imaging at the time of initial symptoms helps to streamline and triage patients to the appropriate treatment pathway. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Palpable abdominal masses may arise from the abdominal cavity or the abdominal wall. The differential diagnosis is broad for each variant ranging from benign lipomas, inflammatory processes, to malignant tumors. The imaging approach to diagnosis varies by location. For intra-abdominal masses, contrast-enhanced CT and ultrasound examination have demonstrated accuracy. For abdominal wall masses, which may arise from muscle, subcutaneous tissue, or connective tissue, MRI, CT, and ultrasound all provide diagnostic value. This publication reviews the current evidence supporting the imaging approach to diagnosis of palpable abdominal masses for two variants: suspected intra-abdominal neoplasm and suspected abdominal wall masses. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The range of pathology in adults that can produce abdominal pain is broad and necessitates an imaging approach to evaluate many different organ systems. Although localizing pain prompts directed imaging/management, clinical presentations may vary and result in nonlocalized symptoms. This review focuses on imaging the adult population with nonlocalized abdominal pain, including patients with fever, recent abdominal surgery, or neutropenia. Imaging of the entire abdomen and pelvis to evaluate for infectious or inflammatory processes of the abdominal viscera and solid organs, abdominal and pelvic neoplasms, and screen for ischemic or vascular etiologies is essential for prompt diagnosis and treatment. Often the first-line modality, CT quickly evaluates the abdomen/pelvis, providing for accurate diagnoses and management of patients with abdominal pain. Ultrasound and tailored MRI protocols may be useful as first-line imaging studies, especially in pregnant patients. In the postoperative abdomen, fluoroscopy may help detect anastomotic leaks/abscesses. While often performed, abdominal radiographs may not alter management. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

In patients with end-stage renal disease, the treatment of choice for most patients is renal transplantation. Complications that occur after kidney transplant can be broadly divided into vascular and non-vascular categories. Non-vascular complications can further be divided into surgical and medical categories. When evaluating renal transplant imaging, it is helpful to consider the occurrence of complications in a timeline from time of surgery. Ultrasound is often the first modality used for evaluation of renal transplants particularly in the early postoperative period. Contrast-enhanced ultrasound can be a helpful adjunct in evaluating certain complications such as hematoma, rejection, and infection. Computed tomography (CT) is also helpful in accurately diagnosing complications. Surgical complications include perinephric fluid collections (hematoma, urinoma from urine leak, abscess, and lymphocele), urinary obstruction, and incisional fluid collections and hernias. One major category of medical complications that affect the renal parenchyma includes rejection (hyperacute, acute, and chronic), delayed graft function, acute tubular necrosis (ATN), and nephrotoxicity. Infection, renal calculi, and neoplasms such as post-transplant lymphoproliferative disease are medical complications that occur after renal transplantation. It is important for radiologists to be aware of the ultrasound and CT findings of the surgical and medical complications after renal transplant for prompt identification and treatment.

Procedure Appropriateness Category Relative Radiation Level CT abdomen and pelvis with IV contrast Usually Appropriate ☢☢☢ CT abdomen and pelvis without IV contrast May Be Appropriate ☢☢☢ MRI abdomen and pelvis without and with IV contrast May Be Appropriate O MRI abdomen and pelvis without IV contrast May Be Appropriate O US abdomen transabdominal May Be Appropriate O CT abdomen and pelvis without and with IV contrast Usually Not Appropriate ☢☢☢☢ Fluoroscopy contrast enema Usually Not Appropriate ☢☢☢ Radiography abdomen and pelvis Usually Not Appropriate ☢☢☢ US pelvis transvaginal Usually Not Appropriate O

Procedure Appropriateness Category Relative Radiation Level CT abdomen and pelvis with IV contrast Usually Appropriate ☢☢☢ CT abdomen and pelvis without IV contrast May Be Appropriate ☢☢☢ US abdomen May Be Appropriate O MRI abdomen and pelvis without and with IV contrast May Be Appropriate O US pelvis May Be Appropriate O MRI abdomen and pelvis without IV contrast May Be Appropriate O CT abdomen and pelvis without and with IV contrast Usually Not Appropriate ☢☢☢☢ Radiography abdomen Usually Not Appropriate ☢☢ Fluoroscopy contrast enema Usually Not Appropriate ☢☢☢ WBC scan abdomen and pelvis Usually Not Appropriate ☢☢☢☢

Soft tissue sarcoma (STS) represents an exceedingly rare group of cancers comprising of 50 histologic subtypes, with approximately 15,000 new diagnoses per year (CA Cancer J Clin 2009;59(4):225-249). Each histologic type exhibits a unique biologic behavior and, as such, prognosis and optimal treatment modalities vary amongst each subtype. This makes the entity as a whole exceedingly complex to diagnose and treat. The natural history of the disease and the treatment options are often tied intimately to each particular histology's genomic underpinnings (Adv Surg 2015;49:107-122), a prime example of which is gastrointestinal stromal tumor and the use of imatinib to target c-kit upregulation (J Clin Oncol 2014;32(15):1563-1570). Additional complexity is derived from the fact that STS may appear anywhere in the body (Figure 1), and the histologic spectrum of disease varies with the location of the primary (Adv Surg 2015;49:107-122). Finally, local invasion of nearby anatomic structures may make surgical resection difficult or impossible.Figure 1.: Intravenous contrast-enhanced CT scan of the chest shows a large, heterogeneous mass of the right pleural space, with an associated right pleural effusion. The patient underwent resection via a right thoracotomy, and pathology revealed leiomyosarcoma.Retroperitoneal STS (RPSTS) is uniquely challenging given its frequent involvement of adjacent organs and the often-large tumor size attributable to a lack symptoms until mass effect occurs. Complete surgical resection to negative margins remains a dominant predictor of outcomes and the only definitive treatment for RPSTS (Ann Surg 2014;260(3):412-416). Resection is uniquely challenging in this anatomic compartment given the proximity to vital structures, as well as the generally large size of these tumors (some greater than 20 cm) (J Surg Res 2007;141(1):105-114). Achieving negative margins is technically difficult and less frequently accomplished than resections for the extremity (J Am Coll Surg 2002;194(4):436-447). Unfortunately, this translates into increased local recurrence and associated mortality (Ann Surg 2002;235(3):424-434, J Clin Oncol 2009;27(1):31-37). Other variables which consistently drive prognosis include tumor histology, tumor grade, and presence of distant metastasis (Ann Surg 2014;260(3):412-416). In patients for whom surgery is not an option, chemotherapy and radiotherapy remain the mainstay of treatment despite generally poor response rates. Targeted therapies with small-molecule inhibitors have gained attention as a result of evolving knowledge regarding the genomic and molecular aberrations of various RPSTS histologies. This review aims to provide a brief overview of current diagnostic and therapeutic strategies in RPSTS, as well as to highlight emerging research that may ultimately serve to improve patient outcomes. Diagnosis & Workup Diagnosis of RPSTS is often delayed secondary to insidious growth, whereby symptoms may only manifest once compression of nearby organs or vascular structures occurs (Figure 2). Initial workup of suspected RPSTS should begin with a thorough history and physical exam followed by cross-sectional imaging. Optimal treatment is a multidisciplinary approach and patients should be referred to centers specializing in sarcoma management.Figure 2.: Intravenous contrast-enhanced CT of the abdomen and pelvis demonstrates a retroperitoneal, extraskeletal osteosarcoma which encases the right iliac artery (white arrow) and vein. This patient presented with right leg swelling and edema with concomitant DVT provoked by iliac vein compromise.Cross-sectional imaging is essential to define the extent of the tumor, identify any distant metastasis, examine local extension, guide biopsy (if necessary), and monitor responses to treatment. CT is the most widely used cross-sectional imaging modality. CT not only delineates the anatomy relevant to operative planning, but frequently allows for identification of the histologic subtype (Radiographics 2017;37(2):462-483). MRI may be used as a complement to CT scan as it has superior contrast resolution (Radiographics 2017;37(2):462-483). PET scan may be useful to identify distant metastasis, but recent meta-analysis has found no benefit with routine use of PET (Cancer TreatRev 2004;30(1):83-101). All patients should have a chest radiograph to evaluate for lung metastasis, with consideration for chest CT in patients with high-grade tumors or size >5 cm (CA Cancer J Clin 2004;54(2):94-109). Biopsy of RPSTS is not always mandatory if the histologic subtype is diagnosed with certainty on cross-sectional imaging and the patient is proceeding directly to surgery. Our group takes a selective approach to core needle biopsy; namely: 1) uncertain histologic diagnosis; 2) when imaging suggests a pathology where neoadjuvant chemotherapy or radiation would be appropriate; 3) unresectable or metastatic disease to guide systemic therapies; and 4) strong patient preference. Core needle biopsy is a safe and useful approach in these circumstances, and a histologic diagnosis utilizing this method can be achieved in nearly 90 percent of cases (J Surg Oncol 2010;102(5):523-529). Surgical Management As aforementioned, surgical resection to microscopically negative margins is the ultimate goal of therapy as it represents both a dominant predictor of outcomes and a chance for cure. Resection of RPSTS and extremity STS should be considered separately, not only because the histologies that affect these anatomic locations are distinct (Adv Surg 2015;49:107-122), but RPSTS represents a particular challenge in achieving a satisfactory surgical outcome. Microscopically negative (R0) margins correlate directly with local recurrence/mortality (Ann Surg 2002;235(3):424-434, J Clin Oncol 2009;27(1):31-37) and recurrences beget not only decreased likelihood of complete resection, but increased rates of unresectability (Ann Surg 1998;228(3):355-365, Ann Surg 1990;212(1):51-59). In light of this, several groups have recently pushed for routine extended or “compartmental” resections of RPSTS to maximize R0 resections and thus improve disease-related mortality (Ann Surg Oncol 2012;19(9):2981-2991, Ann Surg Oncol 2010;17(6):1507-1514, Ann Oncol 2012;23(4):1067-1073). This concept has been derived from the strategy utilized in resecting tumors of the extremity, namely that one should aim for margins of 1-2 cm with cuffs of grossly healthy tissue (with concomitant reconstruction of vascular structures if these must be included in the margin). When translated to the retroperitoneum, an extended resection may involve removal of the spleen, colon, kidney (Figure 3), pancreas, or psoas muscle. As many as 60.9 percent of surgical specimens will have involvement of adjacent organs, even if at gross inspection there only seems to be tumor abutment of the involved viscera (Ann Surg Oncol 2011;18(8):2136-2142).Figure 3.: Intravenous contrast-enhanced CT of the abdomen and pelvis shows a high-grade, undifferentiated pleomorphic sarcoma of the retroperitoneum. Local compression of the left renal vein is shown (white arrow). This patient required concomitant left nephrectomy to achieve negative margins.Implementation of aggressive multi-visceral resection in recent literature has yielded improved recurrence rates, but at the cost of increased surgical morbidity. For instance, in the series by Bonvalot and others, 18 percent of the treated patients experienced a surgical complication requiring a secondary invasive procedure, and 12 percent required a second operation (Ann Surg Oncol 2010;17(6):1507-1514). The number of concomitantly resected organs correlated to the morbidity of the procedure, especially when three or more organs were removed (Ann Surg Oncol 2010;17(6):1507-1514). This approach, however, has demonstrated a 3.29-fold reduction in local recurrence after the first operation (J Clin Oncol 2009;27(1):31-37), which is a significant payoff for the observed rates of morbidity. Not all groups ascribe to the compartmental RPSTS as a universal approach, and alternatively apply a more selective approach. Underlying this notion is the observation that when controlling for surgical factors, tumor biology ultimately drives local and distant sarcoma recurrence (Ann Surg 2016;263(3):593-600). Briefly, tumor histologies with a less aggressive phenotype such as well-differentiated liposarcoma (WDLS) may not require extensive multivisceral resections. Similarly, those histologies that metastasize to distant sites early, such as high-grade dedifferentiated liposarcooma (DDLS), leiomyosarcoma (LMS), and undifferentiated pleomorphic sarcoma, may warrant consideration of the benefit of such extensive surgery prior to applying this approach universally (J Surg Oncol 2016;113(3):270-276). As it stands, there are no controlled trials to ascertain which approach is more beneficial, and likely neither is the absolute correct answer. What is clear is that better tools are needed to define the interface between tumor and healthy tissue, and research should focus on melding these approaches to individualize the treatment paradigm. Despite adequate locoregional control, 10-year rates of local recurrence (10-30%) and metastatic disease (35-40%) remain high (Cancer 2014;120(21):3361-3369). Most RPSTS will recur within 2-3 years of treatment (CA Cancer J Clin 2004;54(2):94-109), and the majority of these will be local. When feasible, isolated local recurrences should be treated with resection. This task becomes more difficult as the number of repeat re-resections increases. Ability to achieve a negative margin fall from 57 percent at the first resection to only 10 percent after the third attempt (Ann Surg 1998;228(3):355-365). Figures such as these highlight the need to perform the optimal resection up front as multiple resections begin to exhaust the subsequent operative approaches. Systemic Therapy Chemotherapy Chemotherapy, like all systemic therapies for STS to date, has generated disappointing response rates in those with unresectable disease or distant metastasis and, in RPSTS specifically, only serves a role in the setting of advanced disease. Current regimens have been extrapolated from data including all STS subtypes. Doxorubicin has continued to remain the most frequently utilized and effective single-agent therapy, with response rates of 12-24 percent (Oncology (Williston Park) 2015;29(1):43-50, Nat Rev Clin Oncol 2014;11(4):187-202, Sarcoma 2000;4(3):103-112, Curr Cardiol Rev 2011;7(4):214-220). Another popular agent is ifosfamide, which as a single agent has similar response rates (Oncologist 2007;12(11):1351-1360), however, demonstrates dose-limiting toxicities including myelosuppression, renal failure, and CNS symptoms. These results generated interest in the combination of the two, which was investigated in the EORTC STBSG-62012 trial. This study investigated doxorubicin in combination with ifosfamide as compared to doxorubicin alone. There was no significant difference in overall survival (OS) between the two arms (median survival 12.8 months vs. 14.3 months; p=0.076). However, median progression-free survival (PFS) was significantly longer for the combination (7.4 vs. 4.6 months, HR=0.74, p=0.003), and the objective response rate was doubled (26% from 14%, p < 0.006) (Lancet Oncol 2014;15(4):415-423). As such, doxorubicin alone remains the first-line choice chemotherapy amongst patients with advanced disease. By extension, combination with ifosfamide is generally best utilized in cases of unresectable disease in younger, fit patients where tumor shrinkage may render them a surgical candidate. Gemcitabine, either alone or in combination, has been utilized by some as a second-line regimen. A randomized, phase II study by Maki and others demonstrated gemcitabine and docetaxel in combination yielded superior PFS and OS as compared to gemcitabine alone (median PFS 6.2 months vs. 3.0 months, median OS 17.9 months vs. 11.5 months) (J Clin Oncol 2007;25(19):2755-2763). However, the combination is not superior to an anthracycline-based regimen, as demonstrated by the GeDDiS randomized, phase III analysis comparing gemcitabine and docetaxel to single-agent doxorubicin as first line therapies (Lancet Oncol 2017;18(10):1397-1410). There was no difference between the two regimens at their primary endpoint of 24-week PFS (46.3% [95% CI 37.5-54.6] vs. 46.4% [37.5-54.8], p=0.06). Subgroup analysis of response in LMS versus other histologic subtype also did not reveal any therapeutic benefit (p=0.14). These results re-affirmed doxorubicin-based therapy as the current standard for first line therapy. Targeted Therapies As our understanding of the biology underlying different STS histologies has grown, targeted therapies that exploit these biologic aberrations have begun to emerge as potential therapies, alone or in combination, for advanced RPSTS. A notable example of this is cell-cycle dysregulation in LPS. Cyclin-dependent kinase 4 (CDK4) is overexpressed in over 90 percent of well-differentiated and dedifferentiated samples (Am J Surg Pathol 2007;31(10):1476-1489), which underlies a proliferative advantage via phosphorylation of Rb protein and its action on downstream genes such as MDM2. Palbociclib is an oral CDK4/6 inhibitor that prevents this phosphorylation event and has shown early efficacy in xenograft models (Mol Cancer Ther 2004;3(11):1427-1438). In a phase II study of 48 patients with CDK4-amplified WDLS/DDLS, palbociclib showed a PFS rate of 66 percent at 12 weeks with one partial response noted, which exceeded the predetermined goal of 40 percent PFS (JAMA Oncol 2016;2(7):937-940). An interesting drug derived from the Caribbean sea tunicate Ecteinascidia turbinata that has demonstrated promising efficacy against LMS and LPS is trabectedin. It has been licensed for use in Europe for some time and has recently been approved in the U.S. The mechanism of action is complex and not entirely understood, but research has illustrated that it may act through of repression of transcription factors via direct binding (Oncogene 2014;33(44):5201-5210) and interference in DNA damage repair (Cancers (Basel) 2013;5(2):529-549). In their multi-center, phase III trial comparing trabectedin to dacarbazine, Demetri, et al, showed that trabectedin provided a 45 percent reduction in the risk of disease progression in patients with advanced LMS or LPS (J Clin Oncol 2016;34(8):786-793). Notably, these benefits were translated across both non-uterine and uterine LMS. In a larger set of patients who failed first-line chemotherapy, Samuels, et al, reported that patients with LMS/LPS exhibited longer OS compared with other histologies (16.2 months [95% CI 14.1-19.5] vs. 8.4 months [95% CI 7.1-10.7]), and a slightly higher objective response rate of 6.9 percent (95% CI 4.8-9.6) versus 4.0 percent (95% CI 2.1-6.8) (Ann Oncol 2013;24(6):1703-1709). The drug was well-tolerated with the most common adverse effects being nausea, vomiting, abdominal pain, dyspnea, pneumonia, dehydration, and thrombocytopenia. Tyrosine kinase inhibitors (TKIs) have become a popular therapeutic modality given frequent overexpression of tyrosine kinase receptors and their downstream signaling molecules in solid tumors. Pazopanib represents a multi-TKI against VEGF, PDGF, and c-kit, which has demonstrated promising results in this setting. The PALETTE trial was a multi-institutional, randomized, controlled trial comparing pazopanib alone to placebo. Median PFS was 4.6 months for pazopanib compared with 1.6 months for placebo (HR 0.31, p<0.0001) without a statistically significant difference in OS (Lancet 2012;379(9829):1879-1886). Benefit was seen across all histologic subtypes, including LMS. However, LPS was excluded from the PALETTE trial in light of previously published results from Sleijfer, et al. In that phase II trial, enrollment of LPS was terminated early secondary to what was believed to be poor tumor responses to pazopanib (3/17 patients achieved 3-month PFS) (J Clin Oncol 2009;27(19):3126-3132). Central review of pathologic specimens indicated two additional responding patients who had LPS, thus placing 3-month PFS at 26 percent and, in hindsight, would have allowed continued accrual in trial. In response, Samuels, et al, conducted a phase II trial of pazopanib in LPS alone (Cancer 2017;123(23):4640-4647). The 3-month PFS in their study was markedly better at 68.3 percent (95%CI, 51.9%-81.9%). Their findings have provided evidence of the potential activity of pazopanib in LPS. Sunitinib, another TKI with similar pathway targets to pazopanib (VEGF, PDGF) has demonstrated efficacy in LMS/LPS. In their single-center, phase II study, Mahmood, et al, illustrated 3-month PFS rates of 75 percent and 69.2 percent in untreated patients with LPS and LMS, respectively. In patients who underwent prior treatment with chemotherapy, 3-month PFS was impressively maintained at 62.5 percent for LPS, but fell to 25 percent for LMS. Despite targeting similar pathways (but with less selectivity), dasatinib and sorafenib have not been as successful as pazopanib/sunitinib (Cancer 2016;122(6):868-874, Cancer 2012;118(3):770-776), but may confer a small benefit in select STS histologies (Cancer 2016;122(6):868-874). The reasons underlying differential response to these agents despite similar receptor targets is currently not well understood. Radiation Therapy Radiotherapy (RT) has become a focus in the treatment paradigm of STS as far back as the 1980s, when Rosenberg and others published their landmark study describing limb-sparing surgery in combination with adjuvant RT and changed the landscape of modern sarcoma management (Ann Surg 1982;196(3):305-315). Much of the work in RT has focused on improving the geometric delivery of radiation and minimizing the dose to limit off-target side effects of radiating nearby unaffected vital structures, which is a frequent problem with conventional external beam radiation therapy. Intensity-modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT) have emerged in response to this observation. IMRT and IGRT offer the advantages of superior dose conformity, lower total radiation dose, and reduced exposure of normal tissues. Initial concerns surrounding these novel techniques, which became popularized in the past decade, centered upon the possibility that increased dose conformity would yield higher rates of local recurrence (Cancer Biol Med 2016;13(3):373-383). Fortunately, this has not been the case and, in fact, these technologies have been implemented with improved local recurrence rates (J Clin Oncol 2014;32(29):3236-3241). Reduced exposure of normal tissues has also been shown to confer lower rates of late radiation-induced toxicity. The RTOG-0630 trial was a phase II, multi-institutional, prospective analysis designed to assess late toxicities in extremity STS patients receiving IGRT. Grade 2 or higher toxicities were reduced from 37 percent to 10.5 percent at 2 years (J Clin Oncol 2015;33(20):2231-2238). Studies have begun to assess the effect of combination systemic targeted therapies (particularly anti-angiogenic drugs) and radiation therapy. The SUNXRT trial, which combined sunitinib with preoperative RT was closed early secondary to unacceptably high rates of toxicity and local recurrence (Br J Cancer 2014;111(12):2254-2261). However, the PAZNTIS trial is an ongoing, open-label, multi-center phase II/III trial of combination pazopanib and chemoradiation, which may yield additional insight as to the tolerability and efficacy of such regimens. The role of radiation therapy for RPSTS is controversial. The existing literature is limited by small patient numbers, variable radiation techniques and regimens, as well as lack of prospective evidence. However, selected studies have demonstrated improved outcomes with RT for RPSTS. A nationwide clinical cancer database, which included 9,068 patients, demonstrated a survival benefit with surgery and radiation therapy as compared to surgery alone using propensity score-matched datasets (Lancet Oncol 2016;17(7):966-975). It is particularly challenging to deliver high doses of radiation therapy for RPSTS due to the proximity of adjacent vital organs, including the bowel. However, preoperative RT is generally considered better tolerated than post-operative treatment. A retrospective analysis from MD Anderson of 83 patients who underwent radiation in combination with complete surgical resection demonstrated that all patients with significant RT complications were in the post-operative RT cohort (Int J Radiat Oncol Biol Phys 2007;67(1):158-163). The phase III, randomized-controlled trial STRASS (Surgery With or Without Radiation Therapy in Untreated Nonmetastatic Retroperitoneal Sarcoma; NCT01344018) was originally designed to answer the question if RT prior to surgery improved survival. Unfortunately, this trial closed prematurely and results have gone unpublished. Conclusion RPSTS remains a challenging and lethal surgical disease that requires both a multidisciplinary and individualized approach to therapy. Successful outcomes are hinged upon accurate diagnosis (with biopsy if indicated) and upfront aggressive surgical resection. In cases of metastatic or unresectable disease, systemic therapies continue to have generally poor outcomes and are an active area of research. Radiation therapy, although challenging to administer given the location of these tumors, is a useful adjunct to optimize prevention of local recurrence and has steadily improved in the last few decades. Local recurrence remains the pitfall of outcomes and is a predominant driver of mortality. ANTHONY M. VILLANO, MD, is at the Department of Surgery, MedStar-Georgetown University Hospital, Washington, D.C., and MedStar-Georgetown Surgical Outcomes Research Center, Washington, D.C. KATHRYN M. MASELLI, MD, is in the Department of Surgery, MedStar-Georgetown University Hospital. ANGELA D. LEVY, MD, is at the Department of Radiology, Medstar-Georgetown University Hospital. KEITHR. UNGER, MD, is in the Department of Radiation Oncology, Medstar-Georgetown University Hospital. DENNIS A. PRIEBAT, MD, is at the Department of Hematology/Oncology, MedStar-Washington Hospital Center, Washington, D.C. RAPHAEL E. POLLOCK, MD, PHD, is in the Department of Surgery, Ohio State University Comprehensive Cancer Center, Columbus. WADDAH B AL-REFAIE, MD, FACS, is at the Department of Surgery, MedStar-Georgetown University Hospital, MedStar-Georgetown Surgical Outcomes Research Center, and MedStar Health Research Institute, Washington, D.C.

Procedure Appropriateness Category Relative Radiation Level CT abdomen and pelvis with IV contrast Usually Appropriate ☢☢☢ CT abdomen and pelvis without IV contrast May Be Appropriate ☢☢☢ MRI abdomen and pelvis without and with IV contrast May Be Appropriate O Radiography abdomen and pelvis May Be Appropriate (Disagreement) ☢☢☢ Fluoroscopy small bowel follow-through May Be Appropriate ☢☢☢ MRI abdomen and pelvis without IV contrast May Be Appropriate O CT abdomen and pelvis without and with IV contrast Usually Not Appropriate ☢☢☢☢ CT enteroclysis Usually Not Appropriate ☢☢☢☢ CT enterography Usually Not Appropriate ☢☢☢☢ MR enterography Usually Not Appropriate O US abdomen and pelvis Usually Not Appropriate O Fluoroscopy small bowel enteroclysis Usually Not Appropriate ☢☢☢ MR enteroclysis Usually Not Appropriate O

This review summarizes the relevant literature regarding colorectal screening with imaging. For individuals at average or moderate risk for colorectal cancer, CT colonography is usually appropriate for colorectal cancer screening. After positive results on a fecal occult blood test or immunohistochemical test, CT colonography is usually appropriate for colorectal cancer detection. For individuals at high risk for colorectal cancer (eg, hereditary nonpolyposis colorectal cancer, ulcerative colitis, or Crohn colitis), optical colonoscopy is preferred because of its ability to obtain biopsies to detect dysplasia. After incomplete colonoscopy, CT colonography is usually appropriate for colorectal cancer screening for individuals at average, moderate, or high risk. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Colorectal cancers are common tumors in the United States and appropriate imaging is essential to direct appropriate care. Staging and treatment differs between tumors arising in the colon versus the rectum. Local staging for colon cancer is less integral to directing therapy given radical resection is often standard. Surgical options for rectal carcinoma are more varied and rely on accurate assessment of the sphincter, circumferential resection margins, and peritoneal reflection. These important anatomic landmarks are best appreciated on high-resolution imaging with transrectal ultrasound or MRI. When metastatic disease is suspected, imaging modalities that provide a global view of the body, such as CT with contrast or PET/CT may be indicated. Rectal cancer often metastasizes to the liver and so MRI of the liver with and without contrast provides accurate staging for liver metastases. This article focuses on local and distant staging and reviews the appropriateness of different imaging for both variants.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Upper gastrointestinal bleeding (UGIB) remains a significant cause of morbidity and mortality with mortality rates as high as 14%. This document addresses the indications for imaging UGIB that is nonvariceal and unrelated to portal hypertension. The four variants are derived with respect to upper endoscopy. For the first three, it is presumed that upper endoscopy has been performed, with three potential initial outcomes: endoscopy reveals arterial bleeding source, endoscopy confirms UGIB without a clear source, and negative endoscopy. The fourth variant, "postsurgical and traumatic causes of UGIB; endoscopy contraindicated" is considered separately because upper endoscopy is not performed. When endoscopy identifies the presence and location of bleeding but bleeding cannot be controlled endoscopically, catheter-based arteriography with treatment is an appropriate next study. CT angiography (CTA) is comparable with angiography as a diagnostic next step. If endoscopy demonstrates a bleed but the endoscopist cannot identify the bleeding source, angiography or CTA can be typically performed and both are considered appropriate. In the event of an obscure UGIB, angiography and CTA have been shown to be equivalent in identifying the bleeding source; CT enterography may be an alternative to CTA to find an intermittent bleeding source. In the postoperative or traumatic setting when endoscopy is contraindicated, primary angiography, CTA, and CT with intravenous contrast are considered appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Soft-tissue sarcomas occurring in the abdomen and pelvis are an uncommon but important group of malignancies. Recent changes to the World Health Organization classification of soft-tissue tumors include the movement of gastrointestinal stromal tumors (GISTs) into the soft-tissue tumor classification. GIST is the most common intraperitoneal sarcoma. Liposarcoma is the most common retroperitoneal sarcoma, and leiomyosarcoma is the second most common. GIST, liposarcoma, and leiomyosarcoma account for the majority of sarcomas encountered in the abdomen and pelvis and are discussed in part 1 of this article. Undifferentiated pleomorphic sarcoma (previously called malignant fibrous histiocytoma), dermatofibrosarcoma protuberans, solitary fibrous tumor, malignant peripheral nerve sheath tumor, rhabdomyosarcoma, extraskeletal chondro-osseous sarcomas, vascular sarcomas, and sarcomas of uncertain differentiation uncommonly arise in the abdomen and pelvis and the abdominal wall. Although these lesions are rare sarcomas and their imaging features overlap, familiarity with the locations where they occur and their imaging features is important so they can be diagnosed accurately. The anatomic location and clinical history are important factors in the differential diagnosis of these lesions because metastasis, more-common sarcomas, borderline fibroblastic proliferations (such as desmoid tumors), and endometriosis have imaging findings that overlap with those of these uncommon sarcomas. In this article, the clinical, pathologic, and imaging findings of uncommon soft-tissue sarcomas of the abdomen and pelvis and the abdominal wall are reviewed, with an emphasis on their differential diagnosis.

Despite its declining incidence, gastric cancer (GC) remains a leading cause of cancer-related deaths worldwide. A multimodal approach to GC is critical to ensure optimal patient outcomes. Pretherapy fine resolution contrast-enhanced cross-sectional imaging, endoscopic ultrasound and staging laparoscopy play an important role in patients with newly diagnosed ostensibly operable GC to avoid unnecessary non-therapeutic laparotomies. Currently, margin negative gastrectomy and adequate lymphadenectomy performed at high volume hospitals remain the backbone of GC treatment. Importantly, adequate GC surgery should be integrated in the setting of a multimodal treatment approach. Treatment for advanced GC continues to expand with the emergence of additional lines of systemic and targeted therapies.