This study aimed to validate the effectiveness of MotionFree (MF) in the abdominal region using 2 different PET/CT scanners to determine how to use MF efficiently. Methods: All 198 patients underwent respiratory-gated 18F-FDG PET/CT with MF. Imaging was performed using Discovery MI (DMI) and Discovery IQ (DIQ) PET/CT scanners, and all data were divided into 2 groups in each category (abdominal: upper and lower abdomen, lesion size, <20 mm and ≥20 mm; scanner group: DMI and DIQ). A physician assessed whether the respiratory motion artifacts were reduced with MF. The SUV change rate (ΔSUV) of 80 measurable lesions with and without MF was calculated. The relationship between the ΔSUVs and these groups was compared. Results: Motion artifacts were reduced in 62 of 198 patients (31.3%) in the upper abdomen, in 1 of 198 patients (0.5%) in the lower abdomen, in 51 of 98 patients (52.0%) in the DMI, and in 12 of 100 patients (12.0%) in DIQ with MF. ΔSUVs were significantly higher in the upper abdomen than in the lower abdomen. ΔSUV was up to 58.3% in DMI and up to 47.6% in DIQ. ΔSUVs of lesions with a size of less than 20 mm were significantly higher than those with a lesion size of 20 mm or greater. Although DMI was more effective than DIQ in terms of motion artifacts, both DMI and DIQ have the potential to increase the SUV with MF. MF significantly reduced the respiratory motion artifacts and increased the SUV for lesions smaller than 20 mm in the upper abdomen. Conclusion: MF reduced the motion artifacts in higher-spatial-resolution PET/CT images. In both PET/CT scanners, SUVs in lesions smaller than 20 mm and lesions in the upper abdomen increased significantly with MF. To use MF without increasing the acquisition time, it may be useful to apply it to the upper abdomen.

ObjectiveTexture analysis is one of the lung cancer countermeasures in the field of radiomics. Even though image quality affects texture features, the reproducibility of principal component analysis (PCA)-based data-driven respiratory gating (DDG) on texture features remains poorly understood. Hence, this study aimed to clarify the reproducibility of PCA-based DDG on texture features in non-small cell lung cancer (NSCLC) patients with F-18-Fluorodeoxyglucose (F-18-FDG) Positron emission tomography/computed tomography (PET/CT). MethodsTwenty patients with NSCLC who underwent F-18-FDG PET/CT in routine clinical practice were retrospectively analyzed. Each patient's PET data were reconstructed in two PET groups of no gating (NG-PET) and PCA-based DDG gating (DDG-PET). Forty-six image features were analyzed using LIFEx software. Reproducibility was evaluated using Lin's concordance correlation coefficient (rho c${\rho _c}$) and percentage difference (%Diff). Non-reproducibility was defined as having unacceptable strength (rho c$({\rho _c}$ < 0.8) and a %Diff of >10%. NG-PET and DDG-PET were compared using the Wilcoxon signed-rank test. ResultsA total of 3/46 (6.5%) image features had unacceptable strength, and 9/46 (19.6%) image features had a %Diff of >10%. Significant differences between the NG-PET and DDG-PET groups were confirmed in only 4/46 (8.7%) of the high %Diff image features. ConclusionAlthough the DDG application affected several texture features, most image features had adequate reproducibility. PCA-based DDG-PET can be routinely used as interchangeable images for texture feature extraction from NSCLC patients.

BACKGROUND. Differentiation of primary lung cancers and pulmonary metastases may present a diagnostic dilemma given overlapping CT findings. OBJECTIVE. The purpose of this study was to compare the utility of ringlike peripheral increased iodine concentration and conventional findings for differentiating primary lung cancers from pulmonary metastases on dual-energy CT (DECT). METHODS. This retrospective study included 93 patients (64 men, 29 women; median age, 70 years) who underwent resection of a primary lung cancer (n = 68) or pulmonary metastasis (n = 25) corresponding to a solid lesion on preoperative contrast-enhanced DECT performed between April 2020 and March 2021. Venous phase 120-keV single-energy images, equilibrium phase 66-keV virtual monoenergetic images, and iodine concentration maps were reconstructed. Two radiologists independently assessed lesions for spiculated margins, air bronchograms, rim enhancement, and thin ringlike peripheral high iodine concentration; differences were resolved by consensus. Inter-reader agreement and diagnostic performance were assessed. Multivariable logistic regression analysis incorporated additional patient and lesion characteristics. RESULTS. Interobserver agreement, expressed as kappa, was 0.26 for spiculated margins, 0.60 for air bronchograms, 0.56 for rim enhancement, and 0.80 for ringlike peripheral high iodine concentration. Pulmonary metastases, compared with primary lung cancers, exhibited significantly higher frequency of ringlike peripheral high iodine concentration (52% vs 19%; p = .004) but no significant difference in frequency of spiculated margins (49% vs 32%; p = .17), air bronchograms (36% vs 51%; p = .24), or rim enhancement (4% vs 4%; p > .99). Sensitivity and specificity for diagnosing pulmonary metastasis were 68% and 49% for absence of spiculated margins, 64% and 51% for absence of air bronchograms, 4% and 96% for presence of rim enhancement, and 52% and 81% for presence of ringlike peripheral high iodine concentration. In multivariable analysis including smoking history, lesion diameter, multiple resected lesions, and ringlike peripheral high iodine concentration, the only independent significant predictor of pulmonary metastasis was ringlike peripheral high iodine concentration (OR, 7.81 [95% CI, 2.28-29.60); p = .001). CONCLUSION. Ringlike peripheral high iodine concentration had excellent interobserver agreement and high specificity (albeit poor sensitivity) for differentiating pulmonary metastasis from primary lung cancer and was independently predictive of pulmonary metastasis. CLINICAL IMPACT. Ringlike peripheral high iodine concentration could help guide management of patients with known cancer and an indeterminate solitary nodule.

Introduction. The application of data-driven respiratory gating (DDG) for subcentimeter lesions with respiratory movement remains poorly understood. Hence, this study aimed to clarify DDG application for subcentimeter lesions and the ability of digital Positron emission tomography/computed tomography (PET/CT) system combined with DDG to detect these lesions under three-axis respiration. Methods. Discovery MI PET/CT system and National Electrical Manufacturers Association (NEMA) body phantom with Micro Hollow Sphere (4, 5, 6, 8, 10, and 13 mm) were used. The NEMA phantom was filled with 18 F-FDG solutions of 42.4 and 5.3 kBq/ml for each hot sphere and background region. The 3.6 s cycles of three-axis respiratory motion were reproduced using the motion platform UniTraQ. The PET data acquisition was performed in stationary and respiratory-moving states. The data were reconstructed in three PET groups: stationary (NM-PET), no gating with respiratory movement (NG-PET), and DDG gating with respiratory movement (DDG-PET) groups. For image quality, percent contrast (Q H ); maximum, peak, and mean standardized uptake value (SUV); background region; and detectability index (DI) were evaluated in each PET group. Visual assessment was also conducted. Results. The groups with respiratory movement had deteriorated Q H and SUVs compared with NM-PET. Compared with NG-PET, DDG-PET has significantly improved Q H and SUVs in spheres above 6 mm. The background region showed no significant difference between groups. The SUVmax, SUVpeak, and Q H values of 8 mm sphere were highest in NM-PET, followed by DDG-PET and NG-PET. In visual assessment, the spheres above 6 mm were detected in all PET groups. DDG application did not detect new lesions, but it increased DI and visual score. Conclusions . The application of principal component analysis (PCA)-based DDG algorithm improves both image quality and quantitative SUVs in subcentimeter lesions measuring above 6 mm. Although DDG application cannot detect new subcentimeter lesions, it increases the visual indices.

MotionFree® (AMF) is a data-driven respiratory gating (DDG) algorithm for image processing that has recently been introduced into clinical practice. The present study aimed to verify the accuracy of respiratory waveform and the effects of normal and irregular respiratory motions using AMF with the DDG algorithm. We used a NEMA IEC body phantom comprising six spheres (37-, 28-, 22-, 17-, 13-, and 10 mm diameter) containing 18F. The sphere-to-background ratio was 4:1 (21.2 and 5.3 kBq/mL). We acquired PET/CT images from a stationary or moving phantom placed on a custom-designed motion platform. Respiratory motions were reproduced based on normal (sinusoidal or expiratory-paused waveforms) and irregular (changed amplitude or shifted baseline waveforms) movements. The “width” parameters in AMF were set at 10–60

Myocarditis associated with immune-checkpoint inhibitors (ICIs) is a rare, but critical adverse event. Although endomyocardial biopsy (EMB) is the standard for diagnosis of myocarditis, there is a possibility of false negatives due to sampling errors and local nonavailability of EMB, which may hamper the appropriate diagnosis of myocarditis. Therefore, an alternative criterion based on cardiac magnetic resonance imaging (CMRI) combined with clinical presentation has been proposed, but not emphasized sufficiently. We report a case of myocarditis after ICIs administration, which was diagnosed using CMRI in a 48-year-old male with lung adenocarcinoma. CMRI provides an opportunity to diagnose myocarditis during cancer treatment.

Purpose: The purpose of this study was to investigate whether ex-vivo MRI enables accurate estimation of the invasive component of lung adenocarcinoma. Methods: We retrospectively reviewed 32 patients with lung adenocarcinoma who underwent lung lobectomy. The specimens underwent MRI at 1.5T. The boundary between the lesion and the normal lung was evaluated on a 5-point scale in each three MRI sequences, and a one-way analysis of variance and post-hoc tests were performed. The invasive component size was measured histopathologically. The maximum diameter of each solid component measured on CT and MR T1-weighted (T1W) images and the maximum size obtained from histopathologic images were compared using the Wilcoxon signed-rank test. Inter-reader agreement was evaluated using intraclass correlation coefficients (ICC). Results: T1W images were determined to be optimal for the delineation of the lesions (P < 0.001). The histopathologic invasive area corresponded to the area where the T1W ex-vivo MR image showed a high signal intensity that was almost equal to the intravascular blood signal. The maximum diameter of the solid component on CT was overestimated compared with the maximum invasive size on histopathology (mean, 153%; P < 0.05), while that on MRI was evaluated mostly accurately without overestimation (mean, 108%; P = 0.48). The interobserver reliability of the measurements using CT and MRI was good (ICC = 0.71 on CT, 0.74 on MRI). Conclusion: Ex-vivo MRI was more accurate than conventional CT in delineating the invasive component of lung adenocarcinoma.

OBJECTIVE. Whole-body imaging extending from the vertex of the head to the toes is considered the standard 18F-FDG PET/CT protocol for Merkel cell carcinoma, though the evidence establishing this standard is scant. The purpose of this study was to investigate the clinical impact of PET/CT of the lower extremities in patients with Merkel cell carcinoma, a rare aggressive neuroendocrine tumor of the skin. MATERIALS AND METHODS. A total of 101 patients with Merkel cell carcinoma (mean age, 70.9 years) who underwent whole-body PET/CT were included. PET/CT findings in the lower extremities were evaluated on a per-patient basis, and the results were compared between patients with the primary lesion in the lower extremities (lower extremity primary) and those with the primary lesion located between the head and inguinal regions (body primary). Subsequent clinical evaluation and follow-up imaging were used as the reference standard. RESULTS. In the lower extremity (n = 22) and body (n = 79) primary groups, five and eight patients had true metastases in the lower extremities (p = .15). In the body primary group, all metastases in the lower extremities were part of widespread metastases in the body. In contrast, three of five patients (60%) in the lower extremity primary group had isolated metastases in the lower extremities, which differed significantly from the rate in the body primary group (p = .04). Subgroup analysis that included 48 patients who underwent initial staging examinations showed no metastases in the lower extremities regardless of primary location. CONCLUSION. PET/CT of the lower extremities for patients with body primary lesions of Merkel cell carcinoma should be considered of limited clinical utility.

Purpose Bone scintigraphy (BS) of disseminated skeletal metastasis is sometimes misinterpreted as normal. The use of computer-assisted diagnosis (CAD) may resolve this problem. We investigated the performance of a CAD system, BONENAVI, in the diagnosis of disseminated skeletal metastasis. Methods Cases of disseminated skeletal metastasis were selected from a BS log. These patients’ BSs were analyzed by BONENAVI to obtain an artificial neural network (ANN) and bone scan index (BSI). Clinical features (type of primary cancer, CT type, and BS type) were compared with the BONENAVI (ANN and BSI) results. The BS findings (diffuse increased axial skeleton uptake, inhomogeneity of uptake, proximal extremity contrast, and degree of renal uptake) and ANN or BSI were evaluated. Then, negative ANN patients were presented. Results Fifty-four patients were diagnosed as having disseminated skeletal metastasis. Regarding the primary cancers, 12 had prostate cancer, 16 gastric cancers, 16 breast cancers, and 10 miscellaneous cancers. Total sensitivity of ANN (≥ 0.5) was 76% (41/54). ANN values correlated with the BS type among clinical features. Diffuse increased axial skeleton uptake was mostly correlated with ANN of the BS findings. Conclusion The BONENAVI CAD system was partially helpful in diagnosing disseminated skeletal metastasis, but the sensitivity of BONENAVI was not sufficient and underestimated the disseminated skeletal metastasis. Further improvement of this CAD system is necessary to improve the detectability of disseminated skeletal metastasis.

Kadoya, Yoshisuke MD; Oikado, Katsunori MD; Ishiyama, Mitsutomi MD; Tanaka, Hiroko MD; Matsueda, Kiyoshi MD; Ninomiya, Hironori MD, PhD; Nakao, Masayuki MD; Okumura, Sakae MD; Mun, Mingyon MD, PhD Author Information

Mesenteric panniculitis is a relatively rare fibro-inflammatory condition of the mesentery. In acute phase, it demonstrates avid uptake on Fluorine-18 FDG PET/CT (PET/CT). Thorough assessment is needed to differentiate from viable or recurrent disease in patients with malignant lymphoma because it mimics active lymphomatous disease on PET/CT. In this article, 3 illustrative cases of malignant lymphoma are presented. PET/CT demonstrated new FDG-avid mesenteric lesions at the end-of-treatment evaluation while the original disease showed significant response. Early recurrence was initially suspected, but together with clinical course and findings, active surveillance was opted. Sequential follow-up PET/CTs showed various patterns of metabolic activity over time; it can persist for months or more, or metabolic activity can fluctuate over time. Eventually benignity was confirmed in these cases. These cases underscore the importance of interpretation with clinical context and awareness of chronological metabolic changes of mesenteric panniculitis to determine proper management.

Decompressive craniectomy is occasionally performed for patients with impending brain death, which is intended to relieve critically elevated intracranial pressure to keep effective intracranial perfusion. It has been in debate if this surgery later affects the result of brain perfusion scintigraphy performed as an ancillary test in the course of brain death diagnosis because rigid closed skull is deemed essential to elevate intracranial pressure to the point of total absence of intracranial radiotracer uptake on scintigraphy. The purpose of this study is to elucidate the impact of decompressive craniectomy on the result of brain perfusion scintigraphy in patients with suspected brain death. This retrospective cross-sectional study included consecutive 151 brain perfusion scintigraphy performed in 138 patients with suspected brain death from various causes (male 82 patients, female 56 patients; range 0–74 years; mean age 36.6 years). All exams were indicated due to inconclusive clinical diagnosis of brain death. The scintigraphy protocol consists of immediate flow phase and delayed parenchymal phase planar imaging. Additional SPECT imaging was performed in 15 studies in 14 patients. The results, positive or negative brain flow, were compared between patients with and without decompressive craniectomy using Chi-squared test. As there were patients with repeat studies, analysis was performed for both initial and final exam results. Same dataset was used for initial and final exams in patients with only one exam. Out of 138 patients, 15 patients underwent decompressive craniectomy (11%) and 123 patients were managed medically (89%). On the initial exam, negative brain flow was demonstrated in 11 of 15 patients with craniectomy (73.3%) and 106 of 123 patients without craniectomy (86.2%). On the final exam, negative brain flow was demonstrated 12 of 15 patients with craniectomy (80%) and 111 of 123 patients without craniectomy (90.2%). There were no statistically significant differences between the two groups on both initial and final exams (p = 0.19 and 0.23, respectively). In patients with suspected brain death, history of decompressive craniectomy does not affect the result of brain perfusion scintigraphy.

Sixty six-year-old woman status post ileocecal resection for well-differentiated neuroendocrine tumor in the terminal ileum 7 years ago, who is on octreotide therapy for liver metastases. Ga DOTATATE PET/CT showed soft tissue masses with mildly increased radiotracer uptake in the bilateral subscapular/infrascapular regions. In retrospective image review, these soft tissue masses were first noted 7 years prior and have gradually increased in size over the years. Given the characteristic location and imaging findings, these masses are consistent with benign elastofibroma dorsi instead of metastasis.

Cardiac sarcoidosis is associated with major adverse cardiac events including cardiac arrest, for which anti-inflammatory treatment is indicated. Oral corticosteroid is the mainstay among treatment options; however, adverse effects are a major concern with long-term use. It would be beneficial for providers to predict treatment response and prognosis for proper management strategy of sarcoidosis, though it remains challenging. Fluorine (F)-18 fluorodeoxyglucose (FDG)-positron emission tomography(PET)/computed tomography(CT) has an advantage over anatomical imaging in providing semi-quantitative functional parameters such as standard uptake value (SUV), metabolic volume, and total lesion glycolysis (TLG), which are well-established biomarkers in oncology. However, the relationship between these parameters and treatment response has not been fully investigated in cardiac sarcoidosis. Also, the prognostic value of extracardiac active inflammation noted on FDG-PET/CT in the setting of cardiac sarcoidosis is unclear. The aim of this retrospective study was to investigate the prognostic value of semi-quantitative values of both cardiac and extracardiac disease sites derived from FDG-PET/CT in predicting treatment course in cardiac sarcoidosis.

A 61-year-old woman with metastatic breast cancer presented with migrainelike episodes over the past 10 months. FDG-PET/CT(PET/CT) showed relatively symmetric areas of photopenia predominantly in the bilateral superior parietal lobules. Subsequent contrast-enhanced MRI revealed leptomeningeal metastasis in the bilateral posterior parietal regions with associated vasogenic edema in the adjacent brain parenchyma. There was no clear evidence of parenchymal metastasis onMRI. After chemotherapy, the areas of abnormality resolved on PET/CT 8 months later, and the patient showed interval symptomatic improvement. The present case demonstrates brain parenchymal photopenia on PET/CT as an indirect sign of leptomeningeal metastasis reflecting regional vasogenic edema.

1665 Objectives The aim of this study is to investigate the prognostic significance of the semi-quantitative values derived from F-18 FDG PET/CT such as the maximum SUV (Standard Uptake Value), TLG (Total Lesion Glycolysis), and metabolic volume in predicting treatment response in patients with cardiac sarcoidosis. Methods This retrospective study included 16 patients with suspected cardiac sarcoidosis who demonstrated abnormal myocardial FDG uptake on dedicated cardiac-inflammation FDG PET/CT encompassing the entire chest and upper abdomen, and subsequently underwent corticosteroid therapy for a diagnosis of active cardiac sarcoidosis. Semi-quantitative values (maximum SUV, TLG, and metabolic volume) were derived from the lesions with abnormal FDG uptake in each visualized organ system using a maximum SUV threshold of 2.5 and visual assessment. These values were compared to the daily dose of prednisone at 6 months, dichotomized as either equal or less than 10mg or greater than 10mg, on which the patient was successfully maintained for the following 3 months without any clinical progression. Evidence of disease progression or lack of it was established by review of all subsequent clinical records. Mann-Whitney U test was used for statistical analysis. Results Out of 16 patients, 81.3% (13/16) of the patients showed extracardiac involvement in lymph nodes, 37.5% (6/16) in the lung parenchyma, 18.8% (3/16) in the liver, 25% (4/16) in the spleen, and 18.8% (3/16) in the bone. The lesion with the greatest SUV was identified in the heart in 11 patients (68.7%), in the liver in 1 patient (6.3%), and in either mediastinal or upper abdominal lymph node in 4 patients (25%). The maximum SUV, TLG, and metabolic volume of the total disease in all of the visualized organ systems were 8.8 +/- 3.1, 1340+/- 1849g, and 343 +/- 501mlfor the patients with prednisone therapy of equal or less than 10mg and 12.5 +/- 3.3, 1986 +/- 1054g, 449 +/- 215mlfor the patients with prednisone therapy of greater than 10mg (P= 0.04, 0.17, 0.13, respectively), with statistically significant difference in the maxmum SUV between two groups. None of the uptake metrices in the heart showed any significant statistical difference between the two groups. Conclusions The maximum SUV across all the involved organs of the chest and upper abdomen, not in the heart only, could be a predictor of treatment response to steroid therapy in patients with active cardiac sarcoidosis. This underscores the importance of imaging all sites of potential involvement when evaluating patients with suspected sarcoidosis and not limiting the scan to the cardiac region.

Cardiac metastasis of malignant phyllodes tumor is very rare. We herein report a rare case that developed cardiac metastasis from malignant phyllodes tumor. A 38-year-old woman underwent lumpectomy, and the final pathological findings showed the 5-cm malignant phyllodes tumor partially containing 1 cm of squamous cell carcinoma. Four months after the first surgery, a local recurrence of malignant phyllodes tumor and distant metastases to the bone, lung, pulmonary main trunk, and right ventricle were detected. Mass reduction surgery of cardiac metastasis of the malignant phyllodes tumor was performed to avoid sudden death. In immunohistochemical findings, the tumor was suspected to be originated in myoepithelial cells because of the expression of smooth muscle lineage including α-smooth muscle actin and Calponin1 and highly malignant characteristics showing MIB-1 and p53 highly positive with angiogenesis. Further studies are needed to clarify the effective treatment to these tumors.

Purpose: To determine if dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) parameters such as permeability surface area (PS) and blood volume (BV) allow differentiating between new head and neck (HN) cancer, recurrent HN cancer, and post-treatment benign changes.Method: A total of 35 patients with newly diagnosed, recurrent, and benign post-treatment benign changes underwent DCE-MRI. PS and BV were calculated.Results: PS values of the lesion were 23x10(4)+/- 5.8x10(4) for the newly diagnosed cancer group, 33x10(4)+/- 1.7x10(4) for the recurrent cancer group, and 4.8x10(4)+/- 8.1x10(4) for the post-treatment benign change group (P=.031).Conclusion: Post-treatment benign changes in the HN region had significantly high permeability property than newly diagnosed or previously treated recurrent tumor. (C) 2015 Published by Elsevier Inc

OBJECTIVEThe purpose of this study was to investigate the advantages of contrast-enhanced MRI (CE-MRI) for detecting intravertebral clefts over unenhanced MRI in relation to the time since onset of vertebral fracture.MATERIALS AND METHODSIn this retrospective study, a total of 115 patients (88 women, 27 men; mean age, 77.1 years) who underwent percutaneous vertebroplasty for a single-level compression fracture within 7 days of preprocedural MRI were enrolled. Two radiologists evaluated preprocedural unenhanced MRI (T1-weighted and STIR) and CE-MRI examinations for intravertebral clefts on separate days by consensus. The time from the onset of fracture to MRI was classified into three groups: early phase fractures (< 1 month), late phase fractures (1-3 months), and chronic phase fractures (≥ 3 months). The cement distribution during percutaneous vertebroplasty was used as a reference standard, and detectability of clefts was compared between unenhanced MRI and CE-MRI in relation to the time frame. An analog of the McNemar test was used for analyses.RESULTSThere were 104 patients (90.4%) with and 11 patients (9.6%) without a cleft. The sensitivities of unenhanced MRI and CE-MRI, respectively, for detecting clefts were 60.9% and 91.3% for early phase fractures (p = 0.02); 78.6% and 100% for late phase fractures (p = 0.014); and 92.5% and 94.3% for chronic phase fractures (p = 0.3). The specificities were the same for both groups (100% for each time frame).CONCLUSIONCE-MRI is more sensitive than unenhanced MRI for detecting intravertebral clefts in patents with benign compression fractures less than 3 months old.