Correlation between breast cancer and background parenchymal uptake on 18F-fluorodeoxyglucose positron emission tomography.

PURPOSE: This study aimed to investigate differences in background parenchymal uptake (BPU) between patients with and without breast cancer using 18F-fluorodeoxyglucose positron emission tomography. METHODS: Female patients (n = 130, 62.9 ± 12.7 years) with newly diagnosed breast cancer and 50 healthy participants (59.6 ± 13.3 years) without breast cancer were retrospectively included. BPU was evaluated using the maximum standardized uptake value. Data on participant age, body mass index, blood glucose level, and menopausal status were collected from medical records. Breast density was evaluated using mammography. Logistic regression analysis and receiver operating characteristic curves were used to examine the correlation between breast cancer and various characteristic factors, including BPU. RESULTS: The BPU of patients with breast cancer was significantly higher than that of controls (P < 0.001). The results of logistic regression analysis regarding the presence of breast cancer demonstrated that BPU and menopausal status showed higher odds ratios of 13.6 and 4.25, respectively. The area under the receiver operating characteristic curve for BPU was 0.751. CONCLUSIONS: Patients with breast cancer showed higher 18F-fluorodeoxyglucose-BPU. Glucose metabolism of mammary glands may correlate with the development of breast cancer.

Refractory Burkitt Lymphoma With False-positive and False-negative Mass Detected on Positron Emission Tomography-computed Tomography After Chemotherapy.

A 4-year-old boy with an abdominal mass extending from the spleen to the lower umbilicus was diagnosed with Burkitt lymphoma stage III. Because the fluorodeoxyglucose uptake on positron emission tomography (PET)-computed tomography of the residual splenic tumor remained elevated, splenectomy was performed. The PET-positive area was composed of inflammatory infiltrates, whereas the PET-negative area was composed of a viable tumor surrounded by necrotic or dying tumor cells. The residual tumor may have been false-negative for PET because of its poor proliferative potential. In this case, the comparison of PET-computed tomography and pathologic findings demonstrates the simultaneous presence of a false-positive inflammatory lesion and a false-negative residual tumor.

Validation of deep learning-based computer-aided detection software use for interpretation of pulmonary abnormalities on chest radiographs and examination of factors that influence readers' performance and final diagnosis.

PURPOSE: To evaluate the performance of a deep learning-based computer-aided detection (CAD) software for detecting pulmonary nodules, masses, and consolidation on chest radiographs (CRs) and to examine the effect of readers' experience and data characteristics on the sensitivity and final diagnosis. MATERIALS AND METHODS: The CRs of 453 patients were retrospectively selected from two institutions. Among these CRs, 60 images with abnormal findings (pulmonary nodules, masses, and consolidation) and 140 without abnormal findings were randomly selected for sequential observer-performance testing. In the test, 12 readers (three radiologists, three pulmonologists, three non-pulmonology physicians, and three junior residents) interpreted 200 images with and without CAD, and the findings were compared. Weighted alternative free-response receiver operating characteristic (wAFROC) figure of merit (FOM) was used to analyze observer performance. The lesions that readers initially missed but CAD detected were stratified by anatomic location and degree of subtlety, and the adoption rate was calculated. Fisher's exact test was used for comparison. RESULTS: The mean wAFROC FOM score of the 12 readers significantly improved from 0.746 to 0.810 with software assistance (P = 0.007). In the reader group with < 6 years of experience, the mean FOM score significantly improved from 0.680 to 0.779 (P = 0.011), while that in the reader group with ≥ 6 years of experience increased from 0.811 to 0.841 (P = 0.12). The sensitivity of the CAD software and the adoption rate for the lesions with subtlety level 2 or 3 (obscure) lesions were significantly lower than for level 4 or 5 (distinct) lesions (50% vs. 93%, P < 0.001; and 55% vs. 74%, P = 0.04, respectively). CONCLUSION: CAD software use improved doctors' performance in detecting nodules/masses and consolidation on CRs, particularly for non-expert doctors, by preventing doctors from missing distinct lesions rather than helping them to detect obscure lesions.

Fluorodeoxyglucose-positron emission tomography as a potential alternative tool for functional diagnosis of glycogen storage disease type I.

A 43-year-old woman with genetically confirmed glycogen storage disease type Ib was suspected to have left breast cancer. Fluorodeoxyglucose-positron emission tomography showed high fluorodeoxyglucose accumulation in the whole liver as well as left mammary gland. We consider that high fluorodeoxyglucose accumulation in the liver of patients with glycogen storage disease type I is caused by impaired glucose-6-phosphate metabolism due to the congenital deficiency of glucose-6-phosphatase activities in hepatocytes. This study describes fluorodeoxyglucose-positron emission tomography as a potential alternative tool to diagnose glycogen storage disease type I functionally.

Philadelphia Chromosome-positive Acute Lymphoblastic Leukemia Incidentally Detected by Fluorodeoxyglucose-positron Emission Tomography/Computed Tomography at a Health Checkup.

We herein report a case of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-ALL) that was incidentally detected by fluorodeoxyglucose-positron emission tomography (18F-FDG PET)/computed tomography (CT) at a health checkup. At that time, the findings of a physical examination and blood tests were all normal, except for the diffuse bone marrow uptake (maximum standardized uptake value: 6.3). One month later, when the blood counts remained in the normal ranges, a bone marrow examination confirmed the diagnosis of Ph-ALL. Although a diffuse bone marrow uptake of 18F-FDG is observed in some benign conditions, physicians should also consider the possibility of hematological malignancies, including acute leukemia, even when that is the only abnormal finding.

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.

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.