Extremely low 18F-fluorodeoxyglucose uptake in the brain of a patient with metastatic neuroblastoma and its recovery after chemotherapy: A case report

Commonly, physiological 18F-fluorodeoxyglucose (FDG) uptake in the brain can be observed in 18F-FDG positron emission tomography. Abnormal uptake of 18F-FDG in the brain suggests disorders of central nervous system. Here, we present a case of extremely low 18F-FDG uptake in the brain of a 4-year-old girl with whole-body metastatic neuroblastoma. Almost missing of physiological 18F-FDG uptake in the brain was ascribed at least partly to the metastatic neuroblastoma. The brain could regain physiological 18F-FDG uptake after chemotherapy.

Spontaneous bilateral peri-orbital purpura: an important clinical sign of primary systemic amyloidosis

A 69-year-old woman presented with an 18-month history of recurrent bruising of the eyelids. She was otherwise asymptomatic and systems review was unremarkable. On examination, she had peri-orbital purpura and waxy papules at the inner canthus of both eyes. Macroglossia was also noted. Subcutaneous abdominal biopsy identified amorphous material in the dermis that stained positive for Congo red, with apple-green birefringence seen under polarised microscopy. Immunohistochemistry demonstrated antibodies against lambda light chains. Bone marrow biopsy identified further deposits of immunoglobulin light chain amyloid and a clonal infiltrate with 10%–20% plasma cells, confirming amyloidosis secondary to multiple myeloma. Iodine-123-labelled serum amyloid protein scintigraphy showed no abnormal uptake, thereby excluding significant amyloid deposits in the liver, spleen or kidneys. Cardiac MRI was consistent with early amyloid infiltration. We highlight the importance of dermatological manifestations in amyloidosis, to allow for early diagnosis, potentially limiting end organ involvement.

Development of Combination Methods for Detecting Malignant Uptakes Based on Physiological Uptake Detection Using Object Detection With PET-CT MIP Images

Deep learning technology is now used for medical imaging. YOLOv2 is an object detection model using deep learning. Here, we applied YOLOv2 to FDG-PET images to detect the physiological uptake on the images. We also investigated the detection precision of abnormal uptake by a combined technique with YOLOv2. Using 3,500 maximum intensity projection (MIP) images of 500 cases of whole-body FDG-PET examinations, we manually drew rectangular regions of interest with the size of each physiological uptake to create a dataset. Using YOLOv2, we performed image training as transfer learning by initial weight. We evaluated YOLOv2's physiological uptake detection by determining the intersection over union (IoU), average precision (AP), mean average precision (mAP), and frames per second (FPS). We also developed a combination method for detecting abnormal uptake by subtracting the YOLOv2-detected physiological uptake. We calculated the coverage rate, false-positive rate, and false-negative rate by comparing the combination method-generated color map with the abnormal findings identified by experienced radiologists. The APs for physiological uptakes were: brain, 0.993; liver, 0.913; and bladder, 0.879. The mAP was 0.831 for all classes with the IoU threshold value 0.5. Each subset's average FPS was 31.60 ± 4.66. The combination method's coverage rate, false-positive rate, and false-negative rate for detecting abnormal uptake were 0.9205 ± 0.0312, 0.3704 ± 0.0213, and 0.1000 ± 0.0774, respectively. The physiological uptake of FDG-PET on MIP images was quickly and precisely detected using YOLOv2. The combination method, which can be utilized the characteristics of the detector by YOLOv2, detected the radiologist-identified abnormalities with a high coverage rate. The detectability and fast response would thus be useful as a diagnostic tool.

Diagnostic Use of Post-therapy 131I-Meta-Iodobenzylguanidine Scintigraphy in Consolidation Therapy for Children with High-Risk Neuroblastoma

123I-meta-iodobenzylguanidine (123I-mIBG) scintigraphy is used for evaluating disease extent in children with neuroblastoma. 131I-mIBG therapy has been used for evaluation in children with high-risk neuroblastoma, and post-therapy 131I-mIBG scintigraphy may detect more lesions compared with diagnostic 123I-mIBG scintigraphy. However, no studies have yet revealed the detection rate of hidden mIBG-avid lesions on post-therapy 131I-mIBG whole-body scan (WBS) and SPECT images in neuroblastoma children without mIBG-avid lesions as demonstrated by diagnostic 123I-mIBG scintigraphy. We retrospectively examined the diagnostic utility of post-therapy 131I-mIBG scintigraphy in children who received 131I-mIBG as consolidation therapy. Nineteen children with complete response to primary therapy were examined. Post-therapy 131I-mIBG scintigraphy was performed four days after injection. The post-therapy 131I-mIBG scintigraphy, 4 children exhibited abnormal uptake on the WBS. Post-therapy 131I-mIBG SPECT/CT provided additional information in 2 cases. In total, 6 children exhibited abnormal uptake. The site of abnormal accumulation was on the recurrence site in one case, operation sites in five cases, and bone metastasis in one case. Post-therapy 131I-mIBG scintigraphy could detect residual disease that was not recognized using diagnostic 123I-mIBG scintigraphy in 32% of children with high-risk neuroblastoma and ganglioneuroblastoma. The diagnostic use of post-therapy 131I-mIBG scintigraphy can provide valuable information for detecting residual disease.

Imaging a Fever—Redefining the Role of 2-deoxy-2-[18F]Fluoro-D-Glucose–Positron Emission Tomography/Computed Tomography in Fever of Unknown Origin Investigations

Growing evidence suggests that 2-deoxy-2-[18F]fluoro-D-glucose (18FDG)–positron emission tomography/computed tomography (PET/CT) is a useful imaging technique for the evaluation of fever of unknown origin (FUO). This imaging technique allows for accurate localization of foci of hypermetabolism based on 18FDG uptake in glycolytically active cells that may represent inflammation, infection, or neoplasia. The presence of abnormal uptake can help direct further investigation that may yield a final diagnosis. A lack of abnormal uptake can be reasonably reassuring that these conditions are not present, thereby avoiding unnecessary additional testing. Insurers have not routinely covered outpatient 18FDG-PET/CT for the indication of FUO in the United States. However, data published since 2007 suggest early use in FUO diagnostic evaluations improves diagnostic efficiency and reduces costs. Clinicians and insurers should consider 18FDG-PET/CT as a useful tool when preliminary studies are unrevealing.

MON-250 Late Diagnosis of ACTH-secreting Pulmonary Neuroendocrine Tumor by Repeated 68Ga Dotatate Pet/ct: Influence of Tumor Size in Abnormal Uptake?

Background: 68Ga DOTATATE PET/CT (68Ga-PET) has been proposed as a superior method in identifying ectopic ACTH syndrome (EAS). However, recent systematic review suggests its sensitivity is not as high as believed (1). We report a challenging case of EAS whose source was uncovered only after repeated 68Ga-PET. Clinical Case: A 15-year-old male presented with rapid onset of typical features of Cushing’s syndrome (CS) and metabolic impairment. Hormone evaluation confirmed severe ACTH-dependent CS. Pituitary transsphenoidal surgery was performed due to positive responses in desmopressin stimulation and high dose dexamethasone suppression test, in addition to a 4 mm nodule in pituitary MRI. No tumor was found in surgical specimen and no hormonal improvement was observed after surgery. Inferior petrosal sinus sampling demonstrated no central to peripheral ACTH gradient. Neck US, thorax/abdomen/pelvis CT were negative and PET-CT/FDG was inconclusive. OctreoScan® identified anomalous uptake on left mediastinum and led the patient to a thoracic surgery (TS) with nodule resection at left hilum. Pathology confirmed ACTH positive 10 mm neuroendocrine tumor (NET) infiltrating a lymph node. The patient had transient clinical and hormonal improvement, with recurrence 7 months later. Thoracic CT (T-CT) showed a 7 mm nodule on inferior segment of superior left lobe, PET-CT/FDG and OctreoScan® were negative but abnormal uptake was verified by 68Ga-PET in subcarinal area. A sub centimetric lymph node was resected and pathology confirmed ACTH positive NET, although the patient did not achieve remission. Octreotide LAR, cabergoline and ketoconazole did not control hypercortisolism and bilateral adrenalectomy was performed. Then, T-CT showed stable lung nodule and 2nd 68Ga-PET was negative. One year later, T-CT evidenced growth of lung nodule to 15 mm and 3rd 68Ga-PET demonstrated for the first time, abnormal uptake in this area. The patient underwent resection of left superior lung lobe along with ipsilateral hilar lymph nodes, and histopathology study revealed an ACTH-secreting atypical pulmonary carcinoid tumor with Ki67 of 10% and 5 out of 11 lymph nodes affected. ACTH fell from 288 to 64 pg/mL after surgery. Conclusion: Despite the high sensitivity attributed to 68Ga-PET, false negatives have been reported. In the present case, primary tumor was evidenced by 68Ga-PET seven years after the first resection of a metastatic lymph node, in the 3rd 68Ga-PET assessment and after tumor growth. This adds to the evidence that further studies are needed to better assess the accuracy of 68Ga-PET for EAS. Reference: [1] Varlamov et al. Diagnostic utility of Gallium-68-somatostatin receptor PET/CT in ectopic ACTH-secreting tumors: a systematic literature review and single-center clinical experience. Pituitary 2019; 22:445–455

Three-dimensional radiologic–pathologic correlation of medication-related osteonecrosis of the jaw using 3D bone SPECT/CT imaging

Objectives: The aim of this study was to assess a three-dimensional (3D) correlation between preoperative 3D bone single photon emission CT (SPECT)/CT, which allows the visualization of radiotracer uptake on 3D volume-rendered CT images, and histopathological characteristics in the medication-related osteonecrosis of the jaw (MRONJ). Methods: We conducted a full histopathological assessment of the resected jaws in four patients with Stage 2 or 3 MRONJ. The pathologic results were classified as follows: necrosis without any tissue vascularity (N + V-), necrosis with both vascularity and acute inflammatory cell infiltration due to bacterial infection (N + V+I+), necrosis with regenerative vasculature but no inflammatory cell infiltration (N + V+I-), and chronic inflammation without massive necrosis (N-V +I+). These classifications were correlated with imaging results. Results: The N + V- areas visually represented the area of necrotic bone exposed to the oral cavity and were consistent with defect area of radioisotope uptake in SPECT/CT. The N + V- areas were surrounded by the N + V+I + areas where increased radiotracer uptake was clearly seen. Also, abnormal uptake was found in both of the N + V+I- and N-V +I+ areas. The extensive surgical resections from necrotic core to bloody viable margins were performed in all cases, although one had the recurrence of MRONJ at the margin showing abnormal uptake that histologically represented the N + V+I- area. Conclusions: Radiologic–pathologic correlation of MRONJ could be achieved using 3D SPECT/CT. The presence of regenerative vascularity with necrosis or inflammation seemed to determine bone metabolism in MRONJ. The recurrence of MRONJ was observed in one case, and 3D SPECT/CT had preoperatively depicted the recurrence site.