OBJECTIVE:The purpose of this article is to discuss the systemic nature of autoimmune pancreatitis and its various pancreatic and extrapancreatic imaging findings.CONCLUSION:Autoimmune pancreatitis is a systemic disease with a wide range of pancreatic and extrapancreatic imaging findings. These findings can mimic those of other diseases in the pancreas or other organs and therefore are commonly misdiagnosed and mistreated. It is important for radiologists to understand both the pancreatic and extrapancreatic imaging findings of autoimmune pancreatitis to make accurate and timely diagnoses.

The aim of this study was to assess the ability of dual-energy computed tomography (DECT) to classify phantom renal lesions as cysts or enhancing masses. Six cylinders ranging in diameter from 0.5 to 3.0 cm were filled with distilled water or titrated iodinated contrast solutions with CT attenuation values at 120 kVp of 0 Hounsfield units (HU) for a cyst proxy or 10, 20, or 40 HU to represent enhancing masses. These were placed in a 12-cm-diameter renal phantom containing puréed beef mixed with iodinated contrast medium to simulate enhancing renal parenchyma of 100 and 250 HU and submerged within a 28-cm water bath. These combinations produced 48 individual phantom renal lesions of differing sizes, internal and parenchymal enhancement (12 cysts and 36 enhancing masses). DECT using 80 and 140 kVp was performed on a dual-source CT scanner. Commercial software created a color-encoded overlay indicating the location of iodine within the phantom. The lesions were individually graded as a cyst or enhancing mass by blinded, consensus interpretation of two genitourinary radiologists. Thirty-five of 36 enhancing masses and 10/12 cysts were correctly identified, equating to a sensitivity and specificity of 97% (95% CI 84–100%) and 83% (95% CI 51–97%), respectively. All lesions of 20- and 40-HU enhancement and 92% of 10-HU lesions were identified correctly. In a phantom model, the DECT iodine overlay technique is highly sensitive in detecting enhancing renal masses. Refinement of the technique remains necessary to improve specificity. If validated in patients, this may obviate the need for unenhanced acquisitions for renal mass characterization.

Purpose: Contrast-enhanced MR Angiography (CE-MRA) is a widely accepted technique for evaluation of the renal arteries; however, recent concerns regarding the development of nephrogenic systemic fibrosis (NSF) after gadolinium contrast agent administration in patients with reduced renal function have emphasized the need for robust non-contrast MRA methods. One such technique is steady state free precession with in-flow inversion recovery (Inhance). We performed both Inhance MRA and 3D CE MRA in 24 patients referred for renal or abdominal MRA and evaluated Inhance images for accuracy in detection of renal artery stenosis as well as image quality and artifacts. Methods: Inhance is a respiratory-triggered 3D steady state free precession sequence in which high arterial signal intensity is achieved via inflow effect during the inversion time of a slab inversion pulse (IR). The IR pulse suppresses static tissue and inflowing venous blood and is applied to the imaging volume and a variable volume inferior to the imaging slab. An axial volume was acquired with the following parameters: TR/TE 4.0/2.0 msec, TI 200 msec, flip angle 70, receiver bandwidth 125kHz, FOV 30-42 cm, section thickness 2 mm, 56 views, imaging matrix 256x256, with parallel imaging acceleration factor 2, spectral spatial saturation pulse, and respiratory triggering. 3D CE MRA was performed in a coronal oblique plane with the following parameters: TR/TE 3.4/1.6ms, flip angle 30, receiver bandwidth 83 kHz, FOV 26-30cm, section thickness 1.6mm, 42 views, matrix 256x224. 0.1 mM/kg gadolinium contrast was injected at 3 ml/s, with the scan delay determined by a test bolus. 24 patients referred for renal or abdominal MRA had both Inhance and 3D CE MRA performed. Inhance images were evaluated independently by two readers who assessed each renal artery for the presence or absence of significant (>50%) stenosis. Two separate readers in consensus graded the CE MRA images in a similar fashion, and also qualitatively assessed visualization of proximal and distal main renal arteries, intrarenal arteries, and accessory arteries in the Inhance and CE MRA sequences using a 5 point scale (1 = uninterpretable, 5 = perfect image). Results: Inhance images were judged interpretable in all cases by one reader and in 23/24 cases by the second reader. CE MRA revealed significant (>50%) stenosis in 11/54 renal arteries. Sensitivity and specificity for detection of significant (>50%) renal artery stenosis for the two readers versus CE MRA are listed in Table 1. Reader 1 detected 52/54 renal arteries; reader 2 did not evaluate 9 accessory renal arteries, which reduced his sensitivity relative to reader 1. Two accessory arteries were not detected by reader 1: these were not included in the Inhance FOV, and one of these had a severe stenosis. Examples of Inhance and conventional CE MRA images in a patient with significant renal artery stenosis are shown in Fig. 1. Fig. 2 shows ratings of image quality for proximal and distal main renal arteries, intrarenal branches, and accessory arteries.

Purpose: Iodinated contrast excreted into the renal collecting systems and ureters is of similar CT attenuation as kidney stones, making stones difficult or impossible to detect in contrast‐enhanced CT scans. This necessitates precontrast imaging for kidney stone work‐up. Our purpose was to determine the ability of CT dual‐energy subtraction imaging to selectively remove iodine signal while preserving the signal from kidney stones. Method and Materials: A phantom containing twenty kidney stones with different composition (calcium oxalate monohydrate, calcium hydroxyapatite, uric acid) and size (2 – 6 mm) was scanned with the stones surrounded by water or an iodine/water solution (500, 1000, 1400, 1900, 2300 HU at 120 kV) using a dual‐source CT system (Siemens Definition) and 80/140 kV tube potentials. Iodine calibration curves were generated to determine the CT‐number ratio between the low and high‐kV images and energy subtraction images created. Patients with known stone disease were scanned using the same radiation dose as for single‐energy CT as part of clinically‐indicated examinations. Subtraction images were created and compared to images of the known stone location. Results: Image subtraction performed using the empirical calibration curves was successful in removing iodine signal and preserving stone signal for all evaluated stones. One calibration factor to remove iodine signal was successful for all concentrations below the saturation limit, demonstrating independence of the technique on iodine concentration. In initial patient studies, the stone(s) remained visible after subtraction of the iodine signal, demonstrating the potential of the technique in vivo . Conclusion: Dual energy CT can successfully remove iodine while preserving the signal associated with renal stones. This capability may allow the elimination of the non‐contrast phase of CT urogram studies, which may decrease the radiation dose to the patient by 50%. Conflict of Interest: Partial research support from Siemens Medical Solutions.

BACKGROUND AND PURPOSE:Cystoscopy and ureteroscopy have limitations in the evaluation for urothelial tumors, and both are invasive. We studied the utility of three-dimensional (3D) CT virtual endoscopy in phantom models.MATERIALS AND METHODS:A phantom pelvis was constructed of Plexiglas, porcine pelvic bones, and processed animal fat and scanned at various table speeds in a four detector-row CT machine for ability to detect "tumors" of Solidwater plastic polymer. Images were reconstructed at slice thicknesses of 2.5 to 5.0 mm and reconstructed in 3D for evaluation by two radiologists with no knowledge of the scanning parameters or tumor location. Similar studies were performed with a ureter model.RESULTS:With 5-mm slices, the sensitivity for bladder tumors ranged from 67% for 2-mm tumors to 100% for 4-mm tumors, with 12 false-positive findings. The overall sensitivity was 86% with 3.75-mm slices with one false positive, and with 2.5-mm slices, the sensitivity was 93%, again with one false positive. For the ureteral tumors, the overall sensitivities and numbers of false positives were 88.9% and eight with 5.0-mm collimation, 88.9% and four with 3.75-mm collimation, and 100% and three with 2.5-mm collimation. The effective radiation dose for all studies was equivalent to that of a standard abdomen/pelvis scan.CONCLUSIONS:Although virtual endoscopy traditionally has had difficulty detecting tumors <5 mm, the multidetector-row CT protocols used in this study could detect most lesions smaller than this. The scan also depicts the other tissues of the pelvis, which is valuable for staging. The 3D images were produced using data from the CT urogram parameters standard at our institution.

The use of magnetic resonance (MR) imaging for the evaluation of biliary disease has increased rapidly in recent years. New developments, such as breath-hold, single-shot techniques have enabled shorter imaging times while providing excellent visualization of the biliary system. In the diagnosis of acute cholecystitis, MR cholangiography is reportedly comparable with ultrasonography in terms of sensitivity and specificity. 1. Regan F. Schaefer D.C. Smith D.P. Petronis J.D. Bohlman M.E. Magnuson T.H. The diagnostic utility of HASTE MRI in the evaluation of acute cholecystitis: half-Fourier acquisition single-shot turbo SE. J Comput Assist Tomogr. 1998; 22: 638-642 Crossref PubMed Scopus (51) Google Scholar , 2. Van Epps K. Regan F. MR cholangiopancreatography using HASTE sequences. Clin Radiol. 1999; 54: 588-594 Abstract Full Text PDF PubMed Scopus (21) Google Scholar , 3. Hakansson K. Leander P. Ekberg O. Hakansson H.O. MR imaging in clinically suspected acute cholecystitis: a comparison with ultrasonography. Acta Radiol. 2000; 41: 322-328 Crossref PubMed Scopus (49) Google Scholar , 4. Park M.S. Yu J.S. Kim Y.H. et al. Acute cholecystitis: comparison of MR cholangiography and US. Radiology. 1998; 209: 781-785 Crossref PubMed Scopus (75) Google Scholar Although the MR imaging findings in acute cholecystitis have been described, 1. Regan F. Schaefer D.C. Smith D.P. Petronis J.D. Bohlman M.E. Magnuson T.H. The diagnostic utility of HASTE MRI in the evaluation of acute cholecystitis: half-Fourier acquisition single-shot turbo SE. J Comput Assist Tomogr. 1998; 22: 638-642 Crossref PubMed Scopus (51) Google Scholar , 2. Van Epps K. Regan F. MR cholangiopancreatography using HASTE sequences. Clin Radiol. 1999; 54: 588-594 Abstract Full Text PDF PubMed Scopus (21) Google Scholar , 3. Hakansson K. Leander P. Ekberg O. Hakansson H.O. MR imaging in clinically suspected acute cholecystitis: a comparison with ultrasonography. Acta Radiol. 2000; 41: 322-328 Crossref PubMed Scopus (49) Google Scholar , 4. Park M.S. Yu J.S. Kim Y.H. et al. Acute cholecystitis: comparison of MR cholangiography and US. Radiology. 1998; 209: 781-785 Crossref PubMed Scopus (75) Google Scholar to our knowledge the MR imaging findings in emphysematous cholecystitis have not yet been reported. We describe a 41-year-old man who was clinically suspected to have cholecystitis and possible choledocholithiasis. He was evaluated initially by MR cholangiography and clinically unsuspected emphysematous cholecystitis was diagnosed and confirmed by computed tomography (CT).

Retrograde urethrography and voiding cystourethrography are the modalities of choice for imaging the urethra. Cross-sectional imaging modalities, including ultrasonography, magnetic resonance (MR) imaging, and computed tomography, are useful for evaluating periurethral structures. Retrograde urethrography is the primary imaging modality for evaluating traumatic injuries and inflammatory and stricture diseases of the male urethra. Sonourethrography plays an important role in the assessment of the thickness and length of bulbar urethral stricture. Although voiding cystourethrography is frequently used to evaluate urethral diverticula in women, MR imaging is highly sensitive in the demonstration of these entities. MR imaging is also accurate in the local staging of urethral tumors.

With the recent introduction of multi-detector row helical computed tomography (CT), the radiologic evaluation of patients with urologic disease has changed rapidly. Two major approaches to CT urography have been developed. The first approach combines axial CT with timed excretory urography (EU) performed by using conventional radiography, digital radiography, or CT scanned projection radiography (SPR). This approach produces traditional projection urograms, and the timed imaging technique is familiar to radiologists and clinicians. Additional excretory phase CT can be performed when the EU findings are positive or indeterminate. Improved CT SPR processing technology produces radiographlike images, thus eliminating patient transportation between the CT and urography suites or the necessity for a CT suite with a ceiling-mounted x-ray tube and a modified CT tabletop for performance of EU. The second approach to CT urography combines axial CT with thin-section excretory phase CT. The near-isotropic volume data set enables creation of high-resolution two- and three-dimensional reformatted images. However, the increased amount of radiation and the time required for data manipulation are concerns. Further studies evaluating large numbers of patients with various urothelial abnormalities will be necessary to determine the optimal CT urography technique for clinical practice.

Urinary tract infection is one of the most common infections in humans. Acute renal infection spans a spectrum of varying severity from uncomplicated acute pyelonephritis through progressively worsening stages of interstitial inflammation to frank abscess formation. The primary goal of renal imaging is to provide information regarding the nature and extent of the disease process and to identify significant complications, such as gas-forming infection, abscess, and urinary obstruction. This article presents a review of the current role of imaging in the diagnosis, treatment, and follow-up of upper urinary tract infection.

Computed tomography plays an important role for the evaluation of most patients with suspected renal injury after trauma. Intravenous urography is used for gross assessment of renal function in hemodynamically unstable patients. Renal injuries can be classified into four large groups: (1) minor renal contusion, lacerations, subcapsular hematoma, and small cortical infarcts; (2) major renal lacerations extending to the medulla with or without involvement of the collecting system; (3) catastrophic renal injuries including fragmentation of the kidney and renal pedicle vascular injuries; and (4) ureteropelvic junction injuries. Integration of the imaging findings of renal injury with clinical information is important to developing a treatment plan.

Computed tomography (CT) is the modality of choice in the evaluation of blunt renal injury. Intravenous urography is used primarily for gross assessment of renal function in hemodynamically unstable patients. Selective renal arteriography or venography can provide detailed information regarding vascular injury. Retrograde pyelography is valuable in assessing ureteral and renal pelvic integrity in suspected ureteropelvic junction injury. Ultrasonography is useful in detecting hemoperitoneum in patients with suspected intraperitoneal injury but has limited value in evaluating those with suspected extraperitoneal injury. Occasionally, radionuclide renal scintigraphy or magnetic resonance imaging may prove helpful. Renal injuries can be classified into four large categories based on imaging findings. Category I renal injuries include minor cortical contusion, subcapsular hematoma, minor laceration with limited perinephric hematoma, and small cortical infarct. Category II lesions include major renal lacerations extending to the medulla with or without involvement of the collecting system and segmental renal infarct. Category III lesions are catastrophic renal injuries and include multiple renal lacerations and vascular injury involving the renal pedicle. Category IV injuries are ureteropelvic junction injuries. CT is particularly useful in evaluating traumatic injuries to kidneys with preexisting abnormalities and can help assess the extent of penetrating injuries in selected patients with limited posterior stab wounds. Integration of the imaging findings in renal injury with clinical information is critical in developing a treatment plan.

OBJECTIVE:To assess the utility of triage guidelines for patients with cholelithiasis and suspected choledocholithiasis, incorporating selective use of magnetic resonance cholangiography (MRC) and endoscopic retrograde cholangiopancreatography (ERCP) before laparoscopic cholecystectomy (LC).SUMMARY BACKGROUND DATA:ERCP is the most frequently used modality for the diagnosis and resolution of choledocholithiasis before LC. MRC has recently emerged as an accurate, noninvasive modality for the detection of choledocholithiasis. However, useful strategies for implementing this diagnostic modality for patient evaluation before LC have not been investigated.METHODS:During a 16-month period, the authors prospectively evaluated all patients before LC using triage guidelines incorporating patient information obtained from clinical evaluation, serum chemistry analysis, and abdominal ultrasonography. Patients were then assigned to one of four groups based on the level of suspicion for choledocholithiasis (group I, extremely high; group 2, high; group 3, moderate; group 4, low). Group 1 patients underwent ERCP and clearance of common bile duct stones; group 2 patients underwent MRC; group 3 patients underwent LC with intraoperative cholangiography; and group 4 patients underwent LC without intraoperative cholangiography.RESULTS:Choledocholithiasis was detected in 43 of 440 patients (9.8%). The occurrence of choledocholithiasis among patients in the four groups were 92.6% (25/27), 32.4% (12/37), 3.8% (2/52), and 0.9% (3/324) for groups 1, 2, 3, and 4, respectively (P <.001). MRC was used for 8.4% (37/440) of patients. Patient triage resulted in the identification of common bile duct stones during preoperative ERCP in 92.3% (36/39) of the patients. Unsuspected common bile duct stones occurred in six patients (1.4%).CONCLUSIONS:The probability of choledocholithiasis can be accurately assessed based on information obtained during the initial noninvasive evaluation. Stratification of risks for choledocholithiasis facilitates patient management with the most appropriate diagnostic studies and interventions, thereby improving patient care and resource utilization.

BJU InternationalVolume 86, Issue s1 p. 70-79 Imaging in acute renal infection A. Kawashima, A. Kawashima Departments of Radiology and Department of Radiology, Lyndon B. Johnson General Hospital, Houston, Texas, USASearch for more papers by this authorC.M. Sandler, C.M. Sandler Departments of Radiology and Department of Radiology, Lyndon B. Johnson General Hospital, Houston, Texas, USASearch for more papers by this authorS.M. Goldman, S.M. Goldman Departments of Radiology and Urology, The University of Texas-Houston Medical School, andSearch for more papers by this author A. Kawashima, A. Kawashima Departments of Radiology and Department of Radiology, Lyndon B. Johnson General Hospital, Houston, Texas, USASearch for more papers by this authorC.M. Sandler, C.M. Sandler Departments of Radiology and Department of Radiology, Lyndon B. Johnson General Hospital, Houston, Texas, USASearch for more papers by this authorS.M. Goldman, S.M. Goldman Departments of Radiology and Urology, The University of Texas-Houston Medical School, andSearch for more papers by this author First published: 02 January 2002 https://doi.org/10.1046/j.1464-410X.2000.00578.xCitations: 24 A. Kawashima, MD, Department of Radiology, The University of Texas-Houston Medical School, Lyndon B. Johnson General Hospital, 5656 Kelley Street, Houston, Texas 77026, USA. e-mail: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume86, Issues1July 2000Pages 70-79 RelatedInformation