Nuclear medicine practice in Japan: a report of the ninth nationwide survey in 2022.

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. The subcommittee sent questionnaires, including the number and category of examinations as well as the kind of the radiopharmaceuticals during the 30 days of June 2022 to all nuclear medicine institutes in Japan. The total numbers of them for the year 2022 were estimated depends on the 1-month data. A total of 1095 institutes responded to the survey, including 364 positron emission tomography (PET) centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1299 in total, with 2.5% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 83.8% and 35.5%, respectively. The number of single-photon tracer studies in 2022 was 1.11 million which means increase in 2.7% in 5 years. Bone scintigraphy was a leading examination (31.0%), followed by myocardial scintigraphy (27.1%) and cerebral perfusion study (23.8%) in order. The percentage of SPECT studies showed an increase from 63.5% in previous survey to 66.8% in this survey. PET centers have also increased from 389 to 412, as compared with the previous one. One hundred and twenty-two PET centers have installed one or two in-house cyclotrons. Increasing trends of the PET studies were observed from 1992 to 2017, the trend changed and PET studies showed 1.5% decrease in 5 years. 18F-FDG accounted for 98.6% (610,497 examinations). PET examinations using 11C-methionine, 13N-NH3 and 11C-PIB have decreased, with 1624, 2146 and 525 examinations, respectively in 2022. The total number of nuclear medicine examination was eventually increased by 1.0%. Therapies for pheochromocytoma or paraganglioma (PPGL) with 131I-MIBG and for neuroendocrine tumor with 177Lu-DOTA-TATE were newly started, however, a total number of targeted radionuclide therapy was decreased by 17.7% because 131I-radioiodine and 223Ra targeted therapies were decreased and supply of some radioisotopes was discontinued. 131I-radioiodine targeted therapy showed a decrease in 5 years (- 15.9%), including 4099 patients for thyroid cancer. The number of out-patient thyroid bed ablation therapy with 1110 MBq of 131I was also decreased to 1015 per year. The number of admission rooms specialized for radionuclide targeted therapy increased from 157 to 160. The number of 223Ra targeted therapies for castration-resistant metastatic prostate cancer (mCRPC) was 1041 patients. This survey was performed during COVID-19 pandemic, however, total number of nuclear medicine examinations was almost same as previous survey (+ 1.0%). Radionuclide therapies with 131I-MIBG and 177Lu-DOTA-TATE were newly started, and new radionuclide therapy will be available in future, therefore, the development of radionuclide therapy will be continued. We are convinced that this survey report is useful in understanding the current status of the nuclear medicine practice in Japan, and in devising the new strategy to strengthen a role of nuclear medicine.

Systemic Vasculitis Following SARS-CoV-2 mRNA Vaccination Demonstrated on FDG PET/CT.

ABSTRACT: Causality regarding adverse events following SARS-CoV-2 mRNA vaccine is undetermined for vasculitis. Herein, we report the case of an 80-year-old man who presented with a persistent high fever of 7 days' duration that began shortly after receiving a COVID-19 vaccination. There was also a complaint of persistent lower limb pain and walking difficulty on emergency transportation. FDG PET/CT demonstrated extensive linear hypermetabolic foci along the vessels of both legs, including the hips, and the arms, supraclavicular area, chest wall, and temporal regions, suggesting systemic vasculitis. Subsequent temporal artery biopsy revealed arteritis, which is not typical of giant cell arteritis.

Predicting tumor response and prognosis to neoadjuvant chemotherapy in esophageal squamous cell carcinoma patients using PERCIST: a multicenter study in Japan.

PURPOSE: To investigate the usefulness of the positron emission tomography response criteria in solid tumors 1.0 (PERCIST1.0) for predicting tumor response to neoadjuvant chemotherapy and prognosis and determine whether PERCIST improvements are necessary for esophageal squamous cell carcinoma (ESCC) patients. PATIENTS AND METHODS: We analyzed the cases of 177 ESCC patients and examined the association between PERCIST and their pathological responses. Associations of whole-PERCIST with progression-free survival (PFS) and overall survival (OS) were evaluated by a Kaplan-Meier analysis and Cox proportional hazards model. To investigate potential PERCIST improvements, we used the survival tree technique to understand patients' prognoses. RESULTS: There were significant correlations between the pathologic response and PERCIST of primary tumor (p < 0.001). The optimal cutoff value of the primary tumors' SULpeak response to classify pathologic responses was -50.0%. The diagnostic accuracy of SULpeak response was 87.3% sensitivity, 54.1% specificity, 68.9% accuracy, positive predictive value 60.5%, and negative predictive value 84.1%. Whole-PERCIST was significantly associated with PFS and OS. The survival tree results indicated that a high reduction of the whole SULpeak response was significantly correlated with the patients' prognoses. The cutoff values for the separation of prognoses were - 52.5 for PFS and - 47.1% for OS. CONCLUSION: PERCIST1.0 can help predict tumor responses and prognoses. However, 18F-FDG-PET/CT tends to underestimate residual tumors in histopathological response evaluations. Modified PERCIST, in which the partial metabolic response is further classified by the SULpeak response (-50%), might be more appropriate than PERCIST1.0 for evaluating tumor responses and stratifying high-risk patients for recurrence and poor prognosis.

Assessment of tumor response to definitive chemoradiotherapy and prognosis prediction in patients with esophageal cancer judged by PET response criteria in solid tumors: multicenter study in Japan.

OBJECTIVES: The aim of the study was to evaluate PET response criteria in solid tumors (PERCIST) to indicate therapeutic response to definitive chemoradiotherapy, as well as prediction of recurrence and death in patients with esophageal cancer. METHODS: Before and after recieving definitive chemoradiotherapy, 181 patients with esophageal cancer underwent fluorodeoxyglucose-PET/computed tomography (FDG-PET/CT). PERCIST, reduction rates of tumor uptake and volume of whole lesions, tumor node metastasis (TNM) staging regarding progression-free survival (PFS), and overall survival (OS) were analyzed using log-rank and Cox methods. RESULTS: Complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD) shown by PERCIST were seen in 42 (23.2%), 113 (62.4%), 14 (7.7%), and 12 (6.6%) patients, respectively. Progression developed in 137 (75.7%) patients and 101 (56.1%) patients died (median follow-up 16.9, range 3.2-124.9 months). Those who achieved CMR showed significantly longer PFS and OS as compared with patients who did not (PMR, SMD, and PMD) (both P < 0.0001). In univariate analysis, initial clinical T status (P = 0.0048), N status (P = 0.011), and TNM stage (P = 0.0006), PERCIST (P < 0.0001), and reduction rate of peak lean body mass standardized uptake value (P < 0.0001), of metabolic tumor volume (P < 0.0001), and of total lesion glycolysis (TLG) (P < 0.0001) were associated with significantly increased OS. Multivariate analysis confirmed PERCIST [hazard ratio (HR): 13.15, 95% confidence interval (CI), 4.54-55.8; P < 0.0001], and TLG reduction rate (HR: 2.21, 95% CI, 1.04-4.68; P = 0.040) as independent OS predictors. CONCLUSION: PERCIST is useful for evaluating therapeutic response to definitive chemoradiotherapy, and predicting progression and death in patients with esophageal cancer.

Diagnosing polymyalgia rheumatica on 18F-FDG PET/CT: typical uptake patterns.

OBJECTIVE: The diagnosis of polymyalgia rheumatica (PMR) is often challenging, since similar clinical features and laboratory findings can be observed in several inflammatory conditions. PMR involves affected sites in a specific manner, and 18F-FDG PET/CT has the advantage for assessing the disease activity of each site. The purpose of this study was to identify the patterns of 18F-FDG uptake that suggest the diagnosis of PMR. METHODS: We studied 60 patients who had undergone 18F-FDG PET/CT scans for workup of suspected PMR, arthritis, enthesitis, or myopathy. Final diagnoses were made by board-certified rheumatologists. The incidence of significant 18F-FDG uptake, higher than mediastinal blood pool, of the following sites were compared among PMR patients and patients with other diseases: wrists, elbows, shoulders, sternoclavicular joints, acromioclavicular joints, spinous processes, ischial tuberosities, and greater trochanters. For the spinous processes, the incidence of "Y"-shaped uptake along the interspinous bursae was also evaluated. RESULTS: A definitive diagnosis of PMR was given to 16 of 60 patients. The incidence of significant 18F-FDG uptake in the definitive PMR group was 6% for wrists and for elbows, 88% for glenohumeral and sternoclavicular joints, 25% for acromioclavicular joints, 81% for spinous processes, 69% for ischial tuberosities, and 81% for greater trochanters. Patients with PMR showed a significantly higher incidence of "Y"-shaped uptake along the interspinous bursae than the other patients (38 vs. 9%) (P = 0.016). CONCLUSION: 18F-FDG uptake distribution patterns and morphology can contribute to the diagnosis of PMR. Significant 18F-FDG uptake in the sternoclavicular joints is one of the characteristic findings in patients with PMR as well as the uptake in the shoulders, ischial tuberosities, and greater trochanters. "Y"-shaped spinous process uptake may be one of the specific findings for PMR.

Response to neoadjuvant chemotherapy for breast cancer judged by PERCIST - multicenter study in Japan.

PURPOSE: The purpose of this study was to evaluate therapeutic response to neoadjuvant chemotherapy (NAC) and predict breast cancer recurrence using Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST). MATERIALS AND METHODS: Fifty-nine breast cancer patients underwent fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) before and after NAC prior to planned surgical resection. Pathological complete response (pCR) of the primary tumor was evaluated using PERCIST, while effects of clinicopathological factors on progression-free survival (PFS) were examined using log-rank and Cox methods. RESULTS: Fifty-six patients and 54 primary tumors were evaluated. Complete metabolic response (CMR), partial metabolic response, stable metabolic disease, and progressive metabolic disease were seen in 45, 7, 3, and 1 patients, respectively, and 43, 7, 3, and 1 primary tumors, respectively. Eighteen (33.3%) of the 54 primary tumors showed pCR. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PERCIST to predict pCR were 100% (18/18), 30.6% (11/36), 41.9% (18/43), 100% (11/11), and 53.7% (29/54), respectively. An optimal percent decrease in peak standardized uptake value for a primary tumor corrected for lean body mass (SULpeak) of 84.3% was found to have a sensitivity of 77.8% (14/18), specificity of 77.8% (28/36), PPV of 63.6% (14/22), NPV of 87.5% (28/32), and accuracy of 77.8% (42/54). Seven (12.5%) of the 56 patients developed recurrent disease (median follow-up 28.1 months, range 11.4-96.4 months). CMR (p = 0.031), pCR (p = 0.024), and early TNM stage (p = 0.033) were significantly associated with longer PFS. CONCLUSION: PERCIST is useful for predicting pathological response and prognosis following NAC in breast cancer patients. However, FDG-PET/CT showed a tendency toward underestimation of the residual tumor, and relatively low specificity and PPV of PERCIST showed that a combination of other imaging modalities would still be needed to predict pCR.

Clinical, Morphologic, and Pathologic Features Associated With Increased FDG Uptake in Schwannoma.

OBJECTIVE: The objective of this study was to investigate the clinical, morphologic, and pathologic features associated with increased 18F-FDG uptake in benign schwannomas. MATERIALS AND METHODS: Twenty-two schwannomas in 22 patients (age range, 25-81 years) who had FDG PET or PET/CT scans and subsequently underwent surgical re-section were retrospectively analyzed. The maximum standardized uptake value (SUVmax) was compared with patient age, sex, tumor location (gastrointestinal vs nongastrointestinal origin), tumor size, gross appearance, intratumoral cellularity, intratumoral infiltration of inflammatory cells, presence of peritumoral lymphoid cuffs, and expression status of glucose transporters 1 and 3 on tumor cells. RESULTS: The SUVmax of schwannomas ranged from 1.5 to 17.3 (median, 3.7). Significantly higher SUVmax was observed in gastrointestinal schwannomas (n = 4) compared with nongastrointestinal schwannomas (n = 18, p = 0.007) and in schwannomas with peritumoral lymphoid cuffs (n = 5) compared with those without peritumoral lymphoid cuffs (n = 17, p = 0.001). A significant correlation was seen between tumor location and the presence of peritumoral lymphoid cuffs (p < 0.001). Age, sex, tumor size, gross appearance, intratumoral cellularity, intratumoral inflammatory cell infiltration, and expression status of glucose transporters 1 and 3 on tumor cells had no significant correlation with SUVmax. CONCLUSION: Gastrointestinal schwannomas and schwannomas with peritumoral lymphoid cuffs may be associated with elevated FDG uptake. Knowledge of the features of schwannomas associated with increased uptake may be helpful to avoid misinterpretation of benign schwannomas as malignancy.

Increased bone marrow uptake of 18F-FDG in leukemia patients: preliminary findings.

The aim of this retrospective study was to evaluate the characteristics of increased bone marrow uptake of 18F-FDG in patients with leukemia who underwent whole-body 18F-FDG PET/CT. The 18F-FDG PET/CT images of 9 patients with histologically proven leukemia were reviewed. The accumulation of 18F-FDG in the bone marrow was evaluated, and was compared with histological subtype, clinical course, and hematological findings. Nine patients (4 males, 5 females; age range, 5-58 years) had increased bone marrow uptake of 18F-FDG, including 6 patients with acute lymphoblastic leukemia, 1 with acute myeloid leukemia, 1 with chronic myeloid leukemia, and 1 with mature B cell neoplasm. Bone marrow uptake was generally diffuse but focal or inhomogeneous uptake was common, especially in the upper and lower extremities. Patients with increased bone marrow uptake of 18F-FDG commonly complained of fever and bone pain. No correlations between 18F-FDG uptake and peripheral blood findings were observed. Patients with leukemia may have increased bone marrow uptake of 18F-FDG on PET/CT, possibly reflecting leukemic cell activity. Leukemia can be included in the differential diagnosis when increased bone marrow uptake of 18F-FDG is observed.

Unilateral physiological FDG uptake in teres minor muscle seems well associated with IV tracer injection procedures.

FDG uptake in teres minor (TM) muscle is often physiologically observed. Here we reviewed data of 578 consecutive patients; TM uptake was observed in 138 patients-in 2 of 68 patients who were administered with FDG via a preexisting line and in 136 of 510 after on-site puncture. In 126 patients with TM uptake without unsuccessful on-site puncture, 78% of TM uptake sites were on the ipsilateral side of injection, 8% on the contralateral side, and 14% on both sides; Cohen κ coefficient was 0.815 when confined to unilateral uptake. Therefore, TM uptake seems well associated with tracer injection procedures.

18F-FDG uptake in intraductal tubulopapillary neoplasm of the pancreas.

We report a 74-year-old man with intraductal tubulopapillary neoplasm (ITPN), a rare primary intraductal neoplasm of the pancreas. Focal intense uptake of 18F-FDG was seen on the initial PET, corresponding to a pancreatic mass. Although the patient had no treatment, the uptake was mild to moderate on a second PET performed about 1 month later. The tumor was resected, with the final diagnosis of ITPN with an associated invasive carcinoma. Clinicians should be aware that decreased uptake of FDG during the follow-up period without treatment can occur even in malignant tumors.

Clinical utility and limitations of FDG PET in detecting recurrent hepatocellular carcinoma in postoperative patients.

BACKGROUND: The clinical usefulness of positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) for the detection of recurrent hepatocellular carcinoma (HCC) is controversial because HCC displays varying FDG avidity. The purposes of this study were to re-evaluate the utility of FDG PET for the detection of recurrent HCC, and to assess its prognostic value in a large series of postoperative patients. METHODS: We retrospectively reviewed 113 scans in 86 patients undergoing FDG PET after curative surgery for HCC. These scans were performed for suspected recurrence on radiologic imaging (group A: n = 44) because of an elevated tumor marker level with negative prior imaging results (group B: n = 32) or with no suspicion of recurrence (group C: n = 37). FDG PET's accuracy for recurrence detection and its value as a predictor of survival were assessed. RESULTS: The sensitivity, specificity, and diagnostic accuracy were 53, 100, and 55 % for group A; 34, 100, and 41 % for group B; and 11, 100, and 78 % for group C, respectively. A change in therapy resulted from the scan results in 7, 9, and 8 % in groups A, B, and C, respectively. The combined sensitivities for intra- and extrahepatic recurrence were 30 and 42 %, respectively. Histopathological features at initial surgery did not affect the sensitivity. The overall survival of patients with positive scans was significantly poorer than that of patients with negative scans (P = 0.008). CONCLUSIONS: The sensitivity of FDG PET for recurrent HCC was low, with little change in treatment resulting. However, it can predict prognosis in postoperative patients.

FDG-PET/CT assessment of misty mesentery: feasibility for distinguishing viable mesenteric malignancy from stable conditions.

PURPOSE: "Misty mesentery" is a CT appearance of mesenteric fat changes with increased attenuation often existing with swelled mesenteric lymph nodes. We evaluated diagnostic performance of FDG-PET/CT in distinguishing viable malignant disorders from benign conditions in misty mesentery. MATERIALS AND METHODS: 4236 FDG-PET/CT images were reviewed to identify patients with appearances of misty mesentery. Only the initial examinations were evaluated. Patients undergoing chemotherapy and/or radiotherapy within 3 months, patients with bulky mesenteric mass, and patients without follow-up examinations were excluded. Maximum short-axis diameter of mesenteric nodules (Diam-max) and maximum standardized uptake value (SUVmax) for mesenteric abnormalities were measured, and the diagnostic performance to differentiate between viable malignancy and stable lesions was assessed by receiver-operating characteristic (ROC) analysis, based on final diagnoses obtained by histology or follow-up examinations. Their significance was assessed by multivariate logistic regression. RESULTS: 71 studies met the inclusion criteria with confirmed diagnoses (13 viable malignancies; 58 stable lesions). Of the 13 malignant cases, 12 were lymphoma. ROC curves indicated an optimal Diam-max cut-off value of >10mm and SUVmax cut-off of ≥3.0, with area under the curve of 0.961 and 0.926, respectively. Using the optimal Diam-max cut-off, sensitivity and specificity were 69% and 98%, respectively. Using the optimal SUVmax cut-off, they were 85% and 98%, respectively. The combination of either Diam-max>10mm or SUVmax≥3.0 had a sensitivity of 92%. Both Diam-max and SUVmax were significant independent factors for predicting malignancy. CONCLUSIONS: FDG-PET/CT is feasible for identifying viable malignancy in misty mesentery.

Clinical value of ¹¹C-methionine PET/CT in patients with plasma cell malignancy: comparison with ¹8F-FDG PET/CT.

PURPOSE: PET/CT using FDG has been widely used for the imaging of various malignant tumours, including plasma cell malignancy (PCM), but (11)C-methionine (MET), as a radiolabelled amino acid tracer, may also be useful because PCM is able to activate protein synthesis. The purpose of this study was to evaluate the clinical value of PET/CT imaging using MET in PCM, including multiple myeloma, compared with that of FDG PET/CT. METHODS: The study group comprised 20 patients with histologically proven PCM who underwent FDG PET/CT and MET PET/CT scans before (n = 6) or after (n = 14) treatment. Semiquantitative analysis was performed on a lesion basis. We also visually evaluated the scans qualitatively using a five-point scale (0, negative; 1, probably negative; 2, equivocal; 3, probably positive; 4, positive) on a lesion and a patient basis. The results were compared between the two scans. RESULTS: Active PCM was confirmed in 15 patients, including two patients with extramedullary lesions. Uptake of MET tended to be higher (maximum standardized uptake value 10.3 ± 5.6, mean ± SD) than that of FDG (3.4 ± 2.7, p < 0.001), and more lesions of grade 3 or 4 were depicted by MET (MET 156 lesions vs. FDG 58 lesions). On a patient basis, two patients were accurately diagnosed only by MET. In the remaining 18 patients, consistent results were obtained, but potential upgrade of staging or restaging was necessary in 6 of 11 positive patients because more abnormal lesions were demonstrated by MET. The patient-based sensitivity, specificity and accuracy of MET for restaging were 89 %, 100 % and 93 %, respectively, while those of FDG were 78 %, 100 % and 86 %, respectively. CONCLUSION: MET revealed an equal or greater number of lesions in PCM than FDG. MET may be especially useful when negative or inconclusive findings are obtained by FDG despite highly suspicious indications of recurrence.

Diffuse homogeneous bone marrow uptake of FDG in patients with acute lymphoblastic leukemia.

PET (positron emission tomography) using FDG (¹8F-fluorodeoxyglucose) has been widely used in the evaluation of various malignancies, but its clinical application to leukemia remains limited. We report a case of leukemia in which diffuse bone marrow uptake of FDG was observed, and bone marrow aspiration subsequently revealed acute lymphoblastic leukemia. It is not easy to differentiate between physiological and pathologic uptake when diffuse homogeneous uptake in bone marrow is observed.

Roles and limitations of FDG PET in pediatric non-Hodgkin lymphoma.

PURPOSE: The usefulness of 18F fluorodeoxyglucose (FDG) positron emission tomography (PET) in pediatric Hodgkin lymphoma (p-HL) has been well demonstrated; however, pediatric non-Hodgkin lymphoma (p-NHL) has distinct characteristics from p-HL and adult NHL. We assessed roles of FDG PET in p-NHL. MATERIALS AND METHODS: Nineteen patients with p-NHL underwent 80 scans. Scans for staging (group A, n=6) and response assessment (group B, n=42) were compared with conventional imaging modalities (CIMs). Scans within group B for end-chemotherapy assessment (subgroup B+, n=11) and for post-therapeutic surveillance (group C, n=32) were analyzed for diagnostic performance. RESULTS: In group A, PET and CIM demonstrated comparable results. In group B, PET diagnoses were concordant with CIM in 21 and discordant in 11 studies. Of the discordant cases, PET suggested remnant lesions in 5 cases, whereas CIM suggested lesions in 6 cases. PET modified therapeutic strategy in 4 cases by detecting new extranodal lesions. In subgroup B+, sensitivity, specificity, and accuracy for predicting relapse were 50%, 71%, and 64%, respectively. In group C, sensitivity, specificity, and accuracy were 100%, 87%, and 88%, respectively, but positive predictive value was 33%. CONCLUSIONS: The role of FDG PET in p-NHL may be limited, unlike with p-HL or adult NHL. Nevertheless, FDG PET may serve complementarily in detecting unexpected lesions that can emerge in p-NHL.

Risk factors for extensive skeletal muscle uptake in oncologic FDG-PET/CT for patients undergoing a 4-h fast.

OBJECTIVES: Postprandial insulin secretion causes extensive skeletal muscle accumulation (ESMA) of fluorine-18 fluorodeoxyglucose (FDG), which adversely affects visual interpretation of FDG-PET/CT. We investigated factors related to ESMA despite a fast of at least 4 h. METHODS: A total of 3595 patients underwent FDG-PET/CT following a fast for at least 4 h. Among them, patients exhibiting ESMA affected by postprandial insulin and sex-matched and age-matched individuals without ESMA as controls were analysed. The following factors were compared: BMI, plasma glucose, presence of diabetes including suspected diabetes (DM-IS), presence of diabetes excluding suspected diabetes, insulin therapy, approximate volume of gastric food residue estimated by CT and residue including water. Multivariate analysis was performed among cases and controls made to fast identically for 4-5 h to assess independent risk factors. RESULTS: Overall, 44 patients with ESMA and 100 controls were identified. The BMI of cases (22.0±3.0) was not significantly different from that of controls (21.5±2.9). Plasma glucose was significantly higher in cases (134.9±44.0 vs. 113.6±31.4 mg/dl; P=0.0050). Cases had a significantly higher proportion of DM-IS, presence of diabetes excluding suspected diabetes, insulin therapy, gastric food residue and residue including water (P<0.0001, P=0.0074, 0.0011, 0.0008 and 0.039, respectively). Logistic regression analysis among 29 cases and 100 controls who had undergone 4-5 h fasting revealed that DM-IS and gastric food residue were independent risk factors for ESMA with odds ratios of 5.14 (P=0.0006) and 5.39 (P=0.0014), respectively. CONCLUSION: It would be preferable to fast for a longer time, especially for patients with glucose intolerance, and avoid heavy meals to reduce gastric residue.

The potential clinical value of FDG-PET for recurrent renal cell carcinoma.

PURPOSE: The clinical value of positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) for follow-up or suspected recurrence of renal cell carcinoma (RCC) has not been fully evaluated. The purpose of this study was to assess the diagnostic performance of FDG-PET for postoperative assessment in patients with RCC. METHODS: We reviewed 28 scans in 23 patients who had undergone FDG-PET scans after surgery for RCC. Diagnostic accuracy of visually interpreted PET was evaluated based on final diagnoses obtained histologically or by clinical follow-up at least 6 months. Also, additional information over CT, influence on treatment decisions, and the accuracy of FDG uptake as a predictor of survival were assessed. RESULTS: Recurrence of renal carcinoma was histologically (n=15) or clinically (n=6) confirmed in 21 of 28 cases. Overall, the sensitivity, specificity, and diagnostic accuracy using FDG-PET were 81%, 71%, and 79%, respectively. In papillary RCC, the sensitivity was 100%; however, that was 75% in clear cell RCC in patient-basis. PET correctly detected local recurrence and metastases in all cases in the peritoneum, bone, muscle and adrenal gland. Additional information was obtained from scans in 6 cases (21%), which influenced therapeutic management in 3 cases (11%). Cumulative survival rates over 5 years in the PET-positive vs. the PET-negative group were 46% vs. 83%, respectively (p=0.17). CONCLUSIONS: FDG-PET would be useful for postoperative surveillance in patients with RCC, although its impact on treatment decisions may be limited. Further investigations are necessary to conclude whether PET has a prognostic value.

MR imaging features of solid-pseudopapillary tumor of the pancreas.

Solid-pseudopapillary tumor (SPT) of the pancreas is characterized as cystic, necrotic, and hemorrhagic degeneration. In this study, magnetic resonance (MR) findings of 4 cases were reviewed. Patchy or spotty areas of high intensity that suggested hemorrhagic degeneration were constantly detected on fat-suppressed T(1)-weighted images. Dynamic contrast-enhanced MR imaging revealed mild and gradual increase of contrast enhancement in solid portions. Multi-contrast MR imaging that included fat-suppressed T(1)-weighted imaging and dynamic contrast-enhanced imaging allowed accurate diagnosis of SPT and its differentiation from other tumors.