Evaluating the Patterns of FAPI Uptake in the Shoulder Joint: a Preliminary Study Comparing with FDG Uptake in Oncological Studies.

BACKGROUND: Fibroblast activation protein inhibitor (FAPI) targeting PET has been introduced as a novel molecular imaging modality for visualizing cancer-associated fibroblasts. There have also been reports suggesting incidental findings of localized accumulation in the shoulder joints. However, further characterization in a larger patient cohort is still lacking. METHODS: 77 consecutive patients (28 females; mean age, 63.1 ± 11.6) who underwent Ga-68 FAPI-04 PET/CT for diagnosis of solid tumors were included. The incidence and localization of tracer uptake in shoulder joints were investigated and compared with available F-18 FDG scans serving as reference. RESULTS: Ga-68 FAPI-04 uptake was evaluated in 77 patients (154 shoulder joints), of whom 54 subjects (108 shoulder joints) also had available F-18 FDG scans for head-to-head comparison. On FAPI-targeted imaging, 67/154 shoulders (43.5%) demonstrated increased radiotracer accumulation in target lesions, which were distributed as follows: acromioclavicular (AC) joints in 25/67 (37.3%), followed by glenohumeral and subacromial (GH + SA) joints in 23/67 (34.3%), or both (AC and GH + SA joints) in the remaining 19/67 (28.4%). Ga-68 FAPI-04 correlated with quantified F-18 FDG uptake (r = 0.69, p < 0.0001). Relative to the latter radiotracer, however, in-vivo FAP expression in the shoulders was significantly increased (Ga-68 FAPI-04, 4.7 ± 3.2 vs F-18 FDG, 3.6 ± 1.3, p < 0.001). CONCLUSION: Our study revealed focal accumulation of Ga-68 FAPI-04 in the shoulders, particularly in the AC joints, with higher uptake compared to the inflammatory-directed PET radiotracer F-18 FDG in oncological studies. As a result, further trials are warranted to investigate the potential of FAPI-directed molecular imaging in identifying chronic remodeling in shoulder joints. This could have implications for initiating anti-FAP targeted photodynamic therapy based on PET signal strength.

Interobserver Agreement Rates on C-X-C Motif Chemokine Receptor 4-Directed Molecular Imaging and Therapy.

BACKGROUND: We aimed to evaluate the interobserver agreement rates in patients scanned with C-X-C motif chemokine receptor 4 (CXCR4)-directed PET/CT, including the rate of patients eligible for CXCR4-targeted radioligand therapy (RLT) based on scan results. METHODS: Four independent observers reviewed 50 CXCR4-targeted [ 68 Ga]pentixafor PET/CT of patients with various solid cancers. On a visual level, the following items were assessed by each reader: overall scan impression, number of organ and lymph node (LN) metastases and number of affected organs and LN regions. For a quantitative investigation, readers had to choose a maximum of 3 target lesions, defined as largest in size and/or most intense uptake per organ compartment. Reference tissues were also quantified, including unaffected hepatic parenchyma and blood pool. Last, all observers had to decide whether patients were eligible for CXCR4-targeted RLT. Concordance rates were tested using intraclass correlation coefficients (ICCs). For interpretation, we applied the definition of Cicchetti (with 0.4-0.59 indicating fair; 0.6-0.74, good; 0.75-1, excellent agreement). RESULTS: On a visual level, fair agreement was achieved for an overall scan impression (ICC, 0.58; 95% confidence interval, 0.45-0.71). Organ and LN involvement (ICC, ≥0.4) demonstrated fair, whereas CXCR4 density and number of LN and organ metastases showed good agreement rates (ICC, ≥0.65). Number of affected organs and affected LN areas, however, showed excellent concordance (ICC, ≥0.76). Quantification in LN and organ lesions also provided excellent agreement rates (ICC, ≥0.92), whereas quantified uptake in reference organs provided fair concordance (ICC, ≥0.54). Again, excellent agreement rates were observed when deciding on patients eligible for CXCR4-RLT (ICC, 0.91; 95% confidence interval, 0.85-0.95). CONCLUSIONS: In patients scanned with CXCR4-targeted PET/CT, we observed fair to excellent agreement rates for both molecular imaging and therapy parameters, thereby favoring a more widespread adoption of [ 68 Ga]pentixafor in the clinic.

Atlas of non-pathological solitary or asymmetrical skeletal muscle uptake in [18F]FDG-PET.

Positron emission tomography (PET) using 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is widely used in oncology and other fields. In [18F]FDG PET images, increased muscle uptake is observed owing exercise load or muscle tension, in addition to malignant tumors and inflammation. Moreover, we occasionally observe non-pathological solitary or unilateral skeletal muscle uptake, which is difficult to explain the strict reason. In most cases, we can interpret them as not having pathological significance. However, it is important to recognize such muscle uptake patterns to avoid misdiagnoses with pathological ones. Therefore, the teaching point of this pictorial essay is to comprehend the patterns of solitary or asymmetrical skeletal muscle uptake seen in routine [18F]FDG-PET scans. As an educational goal, you will be able to mention muscles where intense physiological [18F]FDG uptake can be observed, differentiate between physiological muscle uptake and lesion, and discuss with any physicians or specialists about uncertain muscle uptake.

Visual Assessment of 18F-FDG Uptake on PET to Predict Survival Benefit to PD-1 Blockade in Non-Small Cell Lung Cancer.

BACKGROUND: Programmed death 1 (PD-1) blockade is a standard treatment for patients with metastatic non-small cell lung cancer (NSCLC). Approximately 20% patients receiving PD-1 blockade monotherapy can survive for more than 5 years. However, there are limited data on the optimal biomarkers for predicting long-term outcomes. Therefore, this study aimed to evaluate the prognostic significance of 18F-FDG uptake in patients with NSCLC responding to PD-1 blockade. PATIENTS AND METHODS: Thirty-eight patients with advanced NSCLC who underwent 18F-FDG PET after confirmation of clinical response to PD-1 blockade monotherapy were retrospectively included in this study. Visual assessment using a 5-point scale score according to 18F-FDG uptake was performed, and the 18F-FDG uptake cutoff score for prolonged response to PD-1 blockade was defined as 3 (low score: 1, 2, or 3 and high score: 4 or 5). RESULTS: A significantly greater number of patients with low scores had a performance status of 0 or 1 than patients with high scores. Among the 38 patients, 20 (53%) had a low score and 18 (47%) had a high score. Progression-free survival and overall survival were significantly longer in patients with low scores than in patients with high scores. Low 18F-FDG uptake was an independent prognostic factor for predicting favorable progression-free survival and overall survival, as confirmed by multivariate analysis. CONCLUSIONS: Tumors with lower 18F-FDG uptake on PET than normal hepatic lesions exhibit the possibility of prolonged response to PD-1 blockade. Visual assessment on PET is easy for every clinician and is understandable to confirm aggressive tumor activity.

Diffuse FDG uptake in the bilateral lungs: hypersensitivity pneumonitis supported by low-dose CT findings.

Hypersensitivity pneumonitis (HP) is an interstitial lung disease resulting from an immune-mediated response in susceptible and sensitized individuals to various inhaled antigens in the environment. Imaging diagnosis is usually based on high-resolution CT findings. Here, we present a 49-year-old man with a history of diffuse large B-cell lymphoma presented with fever and occasional cough. 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) revealed diffuse FDG uptake in the bilateral lungs. Expiratory low-dose CT simultaneously performed in PET scanning revealed centrilobular nodules and air trapping in ground glass opacities (GGO). Our imaging diagnosis was acute hypersensitivity pneumonitis (HP). Based on the results of his clinical course, blood laboratory tests, and bronchoscopy, he was diagnosed with acute HP. Diffuse pulmonary FDG uptake can be seen in the patients with acute HP. In addition, expiratory low-dose CT findings of centrilobular nodules and air trapping in GGO may be helpful for accurate diagnosis of acute HP.

Satisfied quantitative value can be acquired by short-time bone SPECT/CT using a whole-body cadmium-zinc-telluride gamma camera.

The aim of this study was to evaluate the quantitative values of short-time scan (STS) of metastatic lesions compared with a standard scan (SS) when acquired by whole-body bone SPECT/CT with cadmium-zinc-telluride (CZT) detectors. We retrospectively reviewed 13 patients with bone metastases from prostate cancer, who underwent SPECT/CT performed on whole-body CZT gamma cameras. STSs were obtained using 75, 50, 25, 10, and 5% of the list-mode data for SS, respectively. Regions of interest (ROIs) were set on the increased uptake areas diagnosed as metastases. Intraclass correlation coefficients (ICCs) of standardized uptake values (SUVs) for the ROIs were calculated between the SS and each STS, and ICC ≥ 0.8 was set as a perfect correlation. Moreover, the repeatability coefficient (RC) was calculated, and RC ≤ 20% was defined as acceptable. A total of 152 metastatic lesions were included in the analysis. The ICCs between the SS vs. 75%-STS, 50%-STS, 25%-STS, 10%-STS, and 5%-STS were 0.999, 0.997, 0.994, 0.983, and 0.955, respectively. The RCs of the SS vs. 75%-STS, 50%-STS, 25%-STS, 10%-STS, and 5%-STS were 7.9, 12.4, 19.8, 30.8, and 41.3%, respectively. When evaluating the quality of CZT bone SPECT/CT acquired by a standard protocol, 25%-STS may provide adequate quantitative values.

Can the function of the tubarial glands be evaluated using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT?

BACKGROUND: The tubarial glands (TGs) are recently reported as newly found salivary gland structures that can be organs at risk predominantly localized in the tori tubarius in the nasopharynx using prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT). The aims of this study were to analyze uptake in the TGs compared with that in the other salivary glands and palatine tonsils using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT and to confirm whether these three imaging modalities are useful in evaluating the physiological function of the TGs. Twelve and 130 patients, who underwent [99mTc]pertechnetate SPECT/CT and [18F]FDG/[11C]methionine PET/CT, respectively, were retrospectively included. [99mTc]pertechnetate uptake in the tori tubarius was visually assessed and semiquantitatively compared with that in the background, parotid salivary glands (PSGs), submandibular salivary glands (SmSGs), and sublingual salivary glands (SlSGs). Correlations of [18F]FDG and [11C]methionine uptakes in the tori tubarius with those in the other three salivary glands and palatine tonsils were analyzed. RESULTS: [99mTc]pertechnetate uptake in the tori tubarius was invisible and was not significantly higher than that in the background. Both [18F]FDG and [11C]methionine uptakes in the tori tubarius were correlated with that in the palatine tonsils (r = 0.56, p < 0.0001; r = 0.48, p < 0.0001, respectively). [18F]FDG uptake in the tori tubarius was not positively correlated with that in the PSGs, SmSGs, and SlSGs (r = - 0.19, p = 0.03; r = - 0.02, p = 0.81; r = 0.12, p = 0.17, respectively). [11C]methionine uptake in the tori tubarius was correlated with that in the SmSGs and SlSGs (r = 0.24, p = 0.01; r = 0.32, p < 0.01, respectively), but not with that in the PSGs (r = 0.16, p = 0.08). CONCLUSIONS: The TGs were undetectable on [99mTc]pertechnetate SPECT/CT. Both [18F]FDG and [11C]methionine uptakes in the tori tubarius were clearly affected by that in the palatine tonsils and was little related to that in the other salivary glands. Therefore, it seems difficult to evaluate the physiological function of the TGs as salivary glands using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT imaging.

Peritoneal dissemination of pancreatic cancer caused by endoscopic ultrasound-guided fine needle aspiration: A case report and literature review.

BACKGROUND: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a biopsy technique widely used to diagnose pancreatic tumors because of its high sensitivity and specificity. Although needle-tract seeding caused by EUS-FNA has been recently reported, dissemination of pancreatic cancer cells is generally considered to be a rare complication that does not affect patient prognosis. However, the frequency of dissemination and needle-tract seeding appears to have been underestimated. We present a case of peritoneal dissemination of pancreatic cancer due to preoperative EUS-FNA. CASE SUMMARY: An 81-year-old man was referred to the Department of Surgery of our hospital in Japan owing to the detection of a pancreatic mass on computed tomography during medical screening. Trans-gastric EUS-FNA revealed that the mass was an adenocarcinoma; hence laparoscopic distal pancreatectomy with lympha-denectomy was performed. No intraoperative peritoneal dissemination and liver metastasis were visually detected, and pelvic lavage cytology was negative for carcinoma cells. The postoperative surgical specimen was negative for carcinoma cells at the dissected margin and the cut end margin; however, pathological findings revealed adenocarcinoma cells on the peritoneal surface proximal to the needle puncture site, and the cells were suspected to be disseminated via EUS- FNA. Hence, the patient received adjuvant therapy with S-1 (tegafur, gimeracil, and oteracil potassium); however, computed tomography performed 5 mo after surgery revealed liver metastasis and cancerous peritonitis. The patient received palliative therapy and died 8 mo after the operation. CONCLUSION: The indications of EUS-FNA should be carefully considered to avoid iatrogenic dissemination, especially for cancers in the pancreatic body or tail.

Mediastinal Cystic Parathyroid Adenoma Diagnosed by Somatostatin Receptor Scintigraphy.

A 71-year-old man complained of nausea and loss of appetite for eight months prior to admission. He was transported to a hospital with disorientation and diagnosed with primary hyperparathyroidism by laboratory examinations. However, ultrasonography, computed tomography, and technetium-99m labeled methoxyisobutyl isonitrile (99mTc-MIBI) with single-photon emission computed tomography did not yield definite results. In contrast, somatostatin receptor scintigraphy successfully identified the lesion responsible for the over-secretion of parathyroid hormone within the middle mediastinum. The tumor was successfully resected by surgery, and a histopathological analysis confirmed the parathyroid adenoma nature of the tumor.

Incidentally detected microcystic serous cystadenoma of the pancreas with splenic invasion: a case report and literature review.

Serous cystic neoplasms are relatively uncommon and rarely possess malignant potential. We report a rare case of pancreatic serous cystadenoma with splenic invasion in a female in her 60s. Dynamic contrast-enhanced CT revealed a 3 cm mass in the tail of the pancreas. The lesion showed marked enhancement in the arterial phase on dynamic CT, which extended into the spleen. No cystic components were detected in the pancreatic mass on either magnetic resonance cholangiopancreatography or T 2 weighted imaging. No metastasis or lymph node swelling was detected. Based on the hypervascularity of the tumour, the pre-operative diagnosis was pancreatic neuroendocrine tumour with splenic invasion. The patient underwent laparoscopic distal pancreatectomy with splenectomy. The pathological diagnosis was microcystic serous cystadenoma with locally aggressive features (infiltration into spleen, lymph nodes, and splenic vein). A few cases of pancreatic serous cystadenomas with splenic invasion have been reported; all were symptomatic, with diameters greater than approximately 9 cm. This is the first known case of incidentally detected serous cystadenoma with splenic invasion, reported with detailed imaging findings of dynamic CT and MRI.

Urgent distal pancreatectomy for intraperitoneal hemorrhage due to the spontaneous rupture of a pancreatic metastatic tumor from synovial sarcoma: a case report.

BACKGROUND: Synovial sarcoma is a soft tissue malignancy that frequently affects the extremities, adjacent to the large joints. Synovial sarcoma has a high rate of distant metastasis; however, pancreatic metastasis is extremely rare, and to our knowledge, there has been no report of bleeding due to spontaneous tumor rupture. This study reports the case of a patient with synovial sarcoma pancreatic metastasis causing tumor rupture and bleeding, which was successfully managed with emergent distal pancreatectomy. CASE PRESENTATION: A 27-year-old woman underwent extensive resection of the primary tumor and partial lung resection after chemotherapy for left femoral synovial sarcoma and multiple lung metastases 4 years prior. During the follow-up, a 35-mm tumor was noted in the pancreatic tail on abdominal computed tomography (CT), and no other distant metastases were detected via positron emission tomography CT. Laparoscopic distal pancreatectomy was scheduled for pancreatic metastasis of synovial sarcoma. However, before the scheduled pancreatectomy could be conducted, the patient visited the emergency department because of abdominal pain that occurred after consuming a small amount of alcohol, and CT showed ascites with high CT values and leakage of contrast media. She was diagnosed with intra-abdominal hemorrhage due to a ruptured metastatic pancreatic tumor, and an emergency operation was performed. In total, 1500 mL of blood was evacuated from the abdomen, and the bleeding pancreatic tail tumor was resected. Histopathological findings revealed synovial sarcoma metastasis and a ruptured tumor capsule, and tumor cells were observed in the hematoma. After discharge on postoperative day 18, the patient was carefully monitored and confirmed to be in relapse-free survival, without chemotherapy, at 6 months post-surgery. CONCLUSIONS: While the rate of tumor growth varies depending on the grade of the tumor, the possibility of rupture should be considered even in metastatic pancreatic tumors. In the case of pancreatic tumor rupture with stable circulation, radiological evaluation for oncology is necessary, and primary resection may be compatible with resectable cases.

Development of 68Ga-labeled tin colloids for evaluating phagocytic function of Kupffer cells using preclinical PET imaging.

OBJECTIVE: This study aimed to investigate the optimal conditions for producing 68Ga-labeled tin colloid and the feasibility of 68Ga-tin colloid positron emission tomography (PET) for visualization and evaluation of the phagocytic function of Kupffer cells (KCs) in vivo. METHODS: 68Ga-tin colloid was prepared by adding tin solution (1 mM, 0.2 mL) to 68Ga solution (1.0 mL), followed by pH adjustment with sodium acetate (1 M, 0.2 mL). Various labeling times were tested to find the optimal one. Colloid size was measured by filtering the solution through three-ply membrane filters (with pore sizes of 200, 3000, and 5000 nm), and radioactivity was measured in the whole filtrate and the filters using a gamma counter. The in vitro stability of the colloid was evaluated by the size measurement after incubation under ambient conditions for up to 60 min. PET scanning was performed for 30 min after intravenous administration of 68Ga-tin colloid solution (4 MBq) to healthy rats. Time-activity-curves for the liver, spleen, and blood pool were generated. Finally, liver uptake was compared before and after the establishment of KC-depletion and non-alcoholic steatohepatitis (NASH) rat models. RESULTS: Colloid size increased with increasing labeling time. After pH adjustment, the colloid sizes remained nearly unchanged. The optimal labeling time was determined as 30 min. PET imaging of healthy rats revealed that liver uptake of the 68Ga-tin colloid increased with increasing colloid size. In KC-depleted rats, liver uptake significantly decreased (n = 4, p < 0.01). NASH model rats showed significantly decreased uptake of 68Ga-tin colloid in the livers (n = 5, p < 0.01). CONCLUSIONS: 68Ga-tin colloid, prepared by a simple radiolabeling method, enabled in vivo PET imaging to evaluate the phagocytic function of KCs.

Usefulness of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography for predicting the prognosis and treatment response of neoadjuvant therapy for pancreatic ductal adenocarcinoma.

BACKGROUND: The Response Evaluation Criteria in Solid Tumors (RECIST) for computed tomography (CT) is preoperatively used to evaluate therapeutic effects. However, it does not reflect the pathological treatment response (PTR) of pancreatic ductal adenocarcinoma (PDAC). The Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) for positron emission tomography (PET)/CT is effective in other cancers. This study aimed to confirm the usefulness of PERCIST and the prognostic utility of PET/CT for PDAC. METHODS: Forty-two consecutive patients with PDAC who underwent neoadjuvant therapy (NAT) and pancreatectomy at our institution between 2014 and 2018 were retrospectively analyzed. We evaluated the treatment response and prognostic significance of PET/CT parameters and other clinicopathological factors. RESULTS: Twenty-two patients who underwent PET/CT both before and after NAT with the same protocol were included. RECIST revealed stable disease and partial response in 20 and 2 cases, respectively. PERCIST revealed stable metabolic disease, partial metabolic response, and complete metabolic response in 8, 9, and 5 cases, respectively. The PTR was G3, G2, and G1 in 8, 12, and 2 cases, respectively. For comparing the concordance rates between PTR and each parameter, PERCIST (72.7% [16/22]) was significantly superior to RECIST (36.4% [8/22]) (P = .017). The area under the curve survival values of PET/CT parameters were 0.777 for metabolic tumor volume (MTV), 0.500 for maximum standardized uptake value, 0.554 for peak standardized uptake value corrected for lean body mass, and 0.634 for total lesion glycolysis. A 50% cut-off value for the MTV reduction rate yielded the largest difference in survival between responders and nonresponders. On multivariate analysis, MTV reduction rates < 50% were independent predictors for relapse-free survival (hazard ratio [HR], 3.92; P = .044) and overall survival (HR, 14.08; P = .023). CONCLUSIONS: PERCIST was more accurate in determining NAT's therapeutic effects for PDAC than RECIST. MTV reduction rates were independent prognostic factors for PDAC.

A case of pancreatic hamartoma with characteristic radiological findings: radiological-pathological correlation.

Pancreatic hamartoma is a rare benign tumor. Its preoperative diagnosis is challenging. We present a case of pancreatic hamartoma whose radiological-pathological correlation was evaluated in detail. A 53-year-old man was referred to our institution for diagnosis and treatment. Contrast-enhanced computed tomography (CT) and magnetic resonance image revealed a 3.5 cm long tumor arising from the head of the pancreas with cystic and solid components, the latter of which was gradually and inhomogeneously enhanced in the delayed phase. Fluorodeoxyglucose (FDG) positron emission tomography/CT revealed slight FDG uptake in the solid component. Histologically, a number of pancreatic lobule-like structures, which were mainly composed of aggregates of small ducts embedded in concentric fibrous stroma with no apparent islets or peripheral nerves, were observed in the solid component, whereas multiple dilated ducts were seen in the cystic region. The solid component also contained a narrow area of edematous fibrous stroma with low vessel density, which corresponded with the unenhanced part in the inhomogeneously enhanced solid component. There was no remarkable cytological atypia throughout the mass. A pathological diagnosis of pancreatic hamartoma was made. The radiological findings agree well with the pathological findings. When a pancreatic tumor is of the solid type, preoperatively diagnosing it as pancreatic hamartoma is not possible. However, when a pancreatic tumor with cystic and solid components is inhomogeneously enhanced in contrast-enhanced studies, a diagnosis of pancreatic hamartoma can be considered.

Evaluation of edge-preserving and noise-reducing effects using the nonlinear diffusion method in bone single-photon emission computed tomography.

OBJECTIVES: This study aims to evaluate nonlinear diffusion (NLD) processing to smoothen images while suppressing resolution degradation in single-photon emission computed tomography (SPECT) images. Phantom data were used for NLD method optimization. The resultant optimal settings were used for NLD processing of clinical images. MATERIALS AND METHODS: Tc was used to simulate tumors and normal soft tissues. Using the data collected, images were reconstructed. Images were processed using various k values and iteration. The background region's coefficient of variation (CV) was determined, and the effects of parameters on image properties were examined. NLD-processed images with optimal parameters were compared with Butterworth (BW)-filtered and nine-point smoothing (SM)-processed images to evaluate smoothing filter properties in real and frequency space. Receiver operating characteristic curve analysis was carried out on NLD-processed and BW048-processed bone SPECT images. RESULTS: From CVs in background, with NLD, increased k value and iteration led to a low CV, indicating enhanced smoothing effect. At k=0.9, a strong noise-reducing effect with less iteration was achieved. Contrasts and recovery coefficients of NLD were the highest. The visual score for SPECT image quality was significantly higher with NLD than with BW048, BW090, and SM. In the low-frequency and high-frequency ranges, BW048, BW090, and NLD showed similar signal strengths and NLD and BW090 showed high signal strength, respectively. SM processing reduced the signal strength at all frequency ranges. On receiver operating characteristic analysis, noise reduction using NLD processing enhanced diagnostic performance than with the use of BW processing. CONCLUSION: NLD processing of bone SPECT images using optimized parameters enabled smoothing with less resolution degradation.

Focal 123I-MIBG Uptake in the Medial Segment of the Normal Liver.

An 84-year-old man with parkinsonism was referred for I-MIBG scintigraphy. Abnormal uptake in the right upper abdomen was incidentally seen in planar image, and SPECT revealed focal uptake in the medial segment (S4) of the liver. Subsequent triple-phase contrast-enhanced CT showed no evidence of hepatic tumors, although in the arterial phase, there were an enhanced region corresponding to the uptake area and the enhanced vein of Sappey that flowed into S4. In this case, the focal I-MIBG uptake would be attributable to hemodynamic change in the liver.

Bilateral Adrenal Hyperplasia Due to Adrenocorticotropic Hormone-Secreting Esthesioneuroblastoma on FDG PET and 111In-Pentetreotide Scintigraphy.

A 53-year-old woman with metastatic esthesioneuroblastoma was referred for FDG PET/CT imaging. FDG PET/CT showed symmetrical uptake in bilaterally enlarged adrenal glands, in addition to abnormal uptake in bone and lymph node metastases. In-pentetreotide scintigraphy was further performed and revealed the lack of adrenal uptake. The patient's serum adrenocorticotropic hormone (ACTH) level was extremely high, suggesting that hyperplastic condition in the adrenal glands due to ACTH stimulation from the metastatic esthesioneuroblastoma was responsible for increased FDG uptake. The combination of FDG PET and In-pentetreotide scintigraphy was useful for the pathophysiological evaluation of ACTH-secreting esthesioneuroblastoma.

Incidental spade-shaped FDG uptake in the left ventricular apex suggests apical hypertrophic cardiomyopathy.

PURPOSE: Apical wall thickening with an "ace-of-spades" configuration is a unique sign of apical hypertrophic cardiomyopathy (AHCM). We investigated spade-shaped FDG uptake around the left ventricular apex (SSUA) incidentally found in routine oncological FDG PET. METHODS: Cases showing SSUA were selected based on retrospective review. The pattern or intensity of SSUA was compared with the results of electrocardiogram (ECG), echocardiography, and stress myocardial perfusion SPECT. The diagnosis of ACHM was based on the presence of giant negative T wave in ECG, thickness of spade-shaped hypertrophy in the apex in echocardiography, and increased tracer uptake in the apex in rest SPECT. RESULTS: Among the 34 patients in 36 PET scans showing SSUA, SSUA was weak in 17 and intense in 17. There were isolated SSUA (n = 29) and SSUA with diffuse or other focal left ventricular uptake (n = 5). Three patients with the latter uptake pattern turned out to have coexistence of AHCM and asymmetric septal hypertrophy. Of the 16 SSUA-positive patients who underwent echocardiography, 13 (81%) were diagnosed as AHCM and the remaining 3 were regarded as borderline AHCM (apical wall thickness, 14-15 mm). There were 16 patients with SSUA who also underwent PET scans after the study period among which 11 (69%) had persistent SSUA in the follow-up PET. In the remaining 5, follow-up PET scans showed diffuse left ventricular uptake and SSUA was barely visible. The intensity of SSUA was significantly or marginally associated with giant negative T wave (p < 0.01), apical asynergy (p = 0.08), and impaired coronary flow reserve (p < 0.05). There were no other factors correlated with the pattern or intensity of SSUA. CONCLUSION: SSUA incidentally found in oncological FDG PET appeared to be associated with AHCM, especially in ischemic conditions. The moderate repeatability of SSUA was probably due to obscurity by physiological uptake.

3D SPECT/CT fusion using image data projection of bone SPECT onto 3D volume-rendered CT images: feasibility and clinical impact in the diagnosis of bone metastasis.

PURPOSE: We developed a method of image data projection of bone SPECT into 3D volume-rendered CT images for 3D SPECT/CT fusion. The aims of our study were to evaluate its feasibility and clinical usefulness. METHODS: Whole-body bone scintigraphy (WB) and SPECT/CT scans were performed in 318 cancer patients using a dedicated SPECT/CT systems. Volume data of bone SPECT and CT were fused to obtain 2D SPECT/CT images. To generate our 3D SPECT/CT images, colored voxel data of bone SPECT were projected onto the corresponding location of the volume-rendered CT data after a semi-automatic bone extraction. Then, the resultant 3D images were blended with conventional volume-rendered CT images, allowing to grasp the three-dimensional relationship between bone metabolism and anatomy. WB and SPECT (WB + SPECT), 2D SPECT/CT fusion, and 3D SPECT/CT fusion were evaluated by two independent reviewers in the diagnosis of bone metastasis. The inter-observer variability and diagnostic accuracy in these three image sets were investigated using a four-point diagnostic scale. RESULTS: Increased bone metabolism was found in 744 metastatic sites and 1002 benign changes. On a per-lesion basis, inter-observer agreements in the diagnosis of bone metastasis were 0.72 for WB + SPECT, 0.90 for 2D SPECT/CT, and 0.89 for 3D SPECT/CT. Receiver operating characteristic analyses for the diagnostic accuracy of bone metastasis showed that WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT had an area under the curve of 0.800, 0.983, and 0.983 for reader 1, 0.865, 0.992, and 0.993 for reader 2, respectively (WB + SPECT vs. 2D or 3D SPECT/CT, p < 0.001; 2D vs. 3D SPECT/CT, n.s.). The durations of interpretation of WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT images were 241 ± 75, 225 ± 73, and 182 ± 71 s for reader 1 and 207 ± 72, 190 ± 73, and 179 ± 73 s for reader 2, respectively. As a result, it took shorter time to read 3D SPECT/CT images than 2D SPECT/CT (p < 0.0001) or WB + SPECT images (p < 0.0001). CONCLUSIONS: 3D SPECT/CT fusion offers comparable diagnostic accuracy to 2D SPECT/CT fusion. The visual effect of 3D SPECT/CT fusion facilitates reduction of reading time compared to 2D SPECT/CT fusion.

RADIATION EXPOSURE TO OPERATORS PERFORMING PHARMACOLOGIC STRESS TESTING IN 99mTc MYOCARDIAL PERFUSION IMAGING: A PROSPECTIVE STUDY.

This prospective study investigated radiation exposure dose (RED) to main operator (MO) and supervisory operator (SO) performing dypiridamole stress testing in a 1-d rest/stress 99mTc tetrofosmin single-photon emission computed tomography (SPECT) of consecutive 42 patients. MO was instructed to be close to the patients during the entire procedures including the vasodilator and radiotracer injection. SO mainly recorded the data on the procedures apart from the patients. RED, procedure time (PT) and internal radioactivity (IR) of patients were measured before and after a secondary tracer injection for stress SPECT, respectively. RED was significantly greater to MO than to SO (6.2 ± 2.7 vs 2.5 ± 2.1 µSV per stress procedure, p < 0.0001). Multivariate analyses revealed that IR and PT were significantly independent factors to predict RED to both operators. Operators performing pharmacologic stress procedure should be aware that IR and PT are independent factors for RED in 99mTc myocardial perfusion imaging.