Clinical Nuclear Medicine

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18F-FET PET for Diagnosis of Pseudoprogression of Brain Metastases in Patients With Non–Small Cell Lung Cancer

imagePurpose
To evaluate whether 18F-fluoroethyltyrosine (FET) PET can discriminate progression from pseudoprogression of brain metastases in patients with non–small cell lung cancer undergoing immunotherapy and radiotherapy to the brain.
Methods
Retrospective analysis of 18F-FET PET scans in cases with documented progression of brain metastases on MRI in a cohort of 53 patients with non–small cell lung cancer receiving immune-checkpoint inhibitors and radiotherapy of brain metastases at the University Hospital of Zürich from June 2015 until January 2019. Response to radiotherapy was assessed by MRI. In case of equivocal findings and/or radiological progression in clinically asymptomatic patients, further assessment with 18F-FET PET was performed.
Results
From the cohort of 53 patients, the restaging MRI showed in 30 patients (56.6%) progression of at least 1 treated metastasis. Thereof, 18F-FET PET was performed in 11 patients, based on the absence of neurological symptoms or presence of systemic response and physicians' decision. 18F-FET PET correctly identified pseudoprogression in 9 of 11 patients (81.8%). In patients who did not undergo 18F-FET PET, 5 of 19 (26.3%) were diagnosed with pseudoprogression.
Conclusions
Pseudoprogression of brain metastases occurred in 50% of patients diagnosed with progression on MRI. 18F-FET PET may help differentiate pseudoprogression from real progression in order to avoid discontinuation of effective therapy or unneeded interventions.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/18F_FET_PET_for_Diagnosis_of_Pseudoprogression_of.4.aspx

Retroperitoneal Liposarcoma on 99mTc-DTPA Renal Scintigraphy

imageRetroperitoneal liposarcoma is usually large and can press on other organs. We report a case of a 66-year-old woman with a history of retroperitoneal liposarcoma resection who presented to the emergency department with abdominal pain. Ultrasonography revealed a large abdominal mass with renal displacement. Dynamic renal scintigraphy with 99mTc-DTPA was conducted to evaluate renal function. However, severe impairment of the right kidney function and abnormal tracer accumulation were observed during the examination. SPECT/CT was performed; 2 kidneys were successfully localized, and the recurrence of tumor was correctly detected.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/Retroperitoneal_Liposarcoma_on_99mTc_DTPA_Renal.9.aspx

Nigrostriatal Degeneration in the Cognitive Part of the Striatum in Parkinson Disease Is Associated With Frontomedial Hypometabolism

imagePurpose
The present study investigated possible associations between cortical dysfunction/degeneration as measured by 18F-FDG PET and nigrostriatal degeneration according to the specific 123I-FP-CIT binding ratio (SBR) in striatal subregions defined by striato-cortical anatomical connectivity in Parkinson disease (PD) patients.
Materials and Methods
The study included 41 patients (61.4 ± 12.8 years) with PD-typical reduction of striatal FP-CIT SBR and no sign of atypical parkinsonian syndrome on FDG PET. FP-CIT SBR was determined separately in the cognitive (composite of executive and limbic) and sensorimotor part of the striatum according to the Oxford-GSK-Imanova Striatal Connectivity Atlas. Scaled FDG uptake was tested voxelwise for correlation with FP-CIT SBR (familywise error corrected P < 0.05).
Results
A large cluster (17.6 mL) of significant correlation of scaled FDG uptake with FP-CIT SBR in the cognitive part of the striatum, corrected for SBR in the sensorimotor part, was detected in the bilateral medial frontal cortex and the anterior cingulate cortex (partial correlation coefficient R = 0.767); small clusters were detected in ipsilateral caudate and ipsilateral thalamus. There was a small contralateral occipital cluster (3.0 mL) of significant correlation between FDG uptake and sensorimotor SBR corrected for cognitive SBR (R = 0.709).
Conclusions
The correlation between nigrostriatal degeneration in the cognitive striatum and reduced cerebral glucose metabolism in the medial parts of the frontal cortex including the anterior cingulate suggests that nigrostriatal degeneration is specifically involved in the pathogenesis of cognitive deficits associated with medial frontal dysfunction such as impaired inhibitory control.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/Nigrostriatal_Degeneration_in_the_Cognitive_Part.1.aspx

Gastric 99mTc-Methylene Diphosphonate Accumulation in a Patient With Primary Upper Gastrointestinal Tract Melanoma

imageUnexpected extraosseous uptake is common on 99mTc–methylene diphosphonate bone scintigraphy, but accumulation by primary upper gastrointestinal tract malignant melanoma is rarely reported. The present case is a 58-year-old woman with a 10-day history of diffuse bone pain and weakness. Her bone scintigraphy showed unexpected diffuse gastric tracer uptake. Subsequent gastroscopy revealed a number of hyperpigmented lesions in the stomach and duodenal bulb. Malignant melanoma was confirmed by histopathology and immunohistochemistry. Because extensive physical examination failed to identify any other site of ocular and cutaneous melanoma, a diagnosis of primary upper gastrointestinal tract malignant melanoma was established.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/Gastric_99mTc_Methylene_Diphosphonate_Accumulation.23.aspx

18F-FDG PET/CT-Guided Diagnosis and Evaluation of Treatment Response to Cyclosporine A in Maldistributed Subcutaneous Panniculitis-like T-Cell Lymphoma Without Typical Skin Rash

imageA 30-year-old woman presented with persistent fever and elevated lactate dehydrogenase levels without skin rash. 18F-FDG PET/CT revealed FDG uptake in subcutaneous tissues in the forearm, buttocks, and lower limbs, whereas the trunk was unaffected. She was diagnosed with subcutaneous panniculitis-like T-cell lymphoma based on a PET/CT-guided subcutaneous tissue biopsy from the thigh. Although conventional cytotoxic agent–based chemotherapies failed to achieve disease remission, subsequent cyclosporine A treatment promptly resolved the fever and laboratory abnormalities. Remarkably, abnormal FDG uptake disappeared entirely on follow-up PET/CT, demonstrating its utility in the evaluations of responses to emerging cyclosporine A–based treatments in subcutaneous panniculitis-like T-cell lymphoma.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/18F_FDG_PET_CT_Guided_Diagnosis_and_Evaluation_of.28.aspx

Nivolumab-Induced Subcutaneous Fat Necrosis: Another FDG-Avid Immune-Related Adverse Event

imageA 59-year-old woman with history of metastatic melanoma, currently on nivolumab, presents for a restaging FDG PET/CT scan. New subcutaneous hypermetabolic foci are seen in bilateral lower extremities, suggestive of recurrent melanoma. She is referred for percutaneous image-guided biopsy for definitive diagnosis of progressive disease. Ultrasound shows the subcutaneous foci to be hyperechoic (fat density), and biopsy of the right thigh nodule shows fat necrosis with no evidence of tumor. Fat necrosis, an immune-related adverse event, can be FDG-avid and mimic malignancy on PET/CT scan.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/Nivolumab_Induced_Subcutaneous_Fat_Necrosis_.7.aspx

Incidence of Radioembolization-Induced Liver Disease and Liver Toxicity Following Repeat 90Y-Radioembolization: Outcomes at a Large Tertiary Care Center

imagePurpose
The complication profile following repeat 90Y-radioembolization (RE) is not well understood, and repeat RE is sometimes avoided because of concerns for RE-induced liver disease (REILD) and liver toxicity. The purpose of this study was to examine the incidence of REILD and liver toxicity following repeat 90Y-RE and to identify potential risk factors.
Methods
A retrospective analysis of patients undergoing repeat RE to the same hepatic lobe between 2013 and 2018 was performed. Baseline factors were evaluated as predictors of liver toxicity, mortality, and REILD, which was defined as the presence symptomatic ascites or jaundice in the absence of biliary obstruction within 8 weeks following RE. Post-RE complications were graded according to the Common Terminology Criteria for Adverse Events version 5.
Results
A total of 39 patients underwent repeat RE with 14 (35.9%) experiencing Common Terminology Criteria for Adverse Events toxicity of grade 2 or greater, 3 (10.3%) grade 3, and no grade 4 or greater. A Model for End Stage Liver Disease score of 8 or greater was associated with grade 2 toxicity or greater (26.7% vs 75%; P = 0.013). Only 3 patients (7.7%) experienced REILD due to symptomatic ascites without jaundice. Greater than 2 REs were associated with a greater rate of 6-month mortality (12% vs 58.3%, P = 0.003), 12-month mortality (28% vs 75%, P = 0.007), and REILD (0% vs 21.4%, P = 0.016). Age, sex, microsphere type, cirrhosis, Child-Pugh, and Eastern Cooperative Oncology Group status were not significantly associated with complications, REILD, or survival.
Conclusions
Repeat 90Y-RE appears to be well tolerated with a low rate of high-grade adverse events and REILD.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/Incidence_of_Radioembolization_Induced_Liver.2.aspx

A Rare Case of Primary Ventricular Lymphoma Presented on FDG PET/CT

imagePrimary ventricular lymphoma is a rare form of non-Hodgkin lymphoma confined to the central nervous system. A 51-year-old woman presented with a 4-month history of unsteady gait and progressive decline in memory. An outside brain MRI showed multiple space-occupying lesions in the ventricles, which suggested malignancy. Staging with FDG PET/CT demonstrated not only hypermetabolic masses in the lateral, third, and fourth ventricles but also a hypermetabolic lesion in the spinal cord. A biopsy of the right lateral ventricle tumor confirmed diffuse large B-cell lymphoma.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/A_Rare_Case_of_Primary_Ventricular_Lymphoma.20.aspx

18F-FDG Uptake of Localized Malignant Peritoneal Mesothelioma

imageWe present 2 cases of malignant peritoneal mesothelioma (MPM) characterized by a localized solid mass without ascites and showing 18F-FDG uptake. A 79-year-old man with a history of asbestos exposure suffered from an epithelioid MPM originating from the hepatoduodenal ligament with FDG uptake (SUVmax 16.8). Another 80-year-old man with esophageal cancer showed desmoplastic MPM of the small bowel mesentery with FDG uptake (SUVmax 4.0). Desmoplastic MPM is more aggressive and yields poorer prognosis compared with the epithelioid type. However, the present desmoplastic MPM case showed mild FDG uptake because of rich fibrosis.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/18F_FDG_Uptake_of_Localized_Malignant_Peritoneal.22.aspx

Breast Cancer Imaging With PET Based Radiopharmaceuticals Other Than 18F-FDG

imageBreast cancer is the most common cancer in women with rising incidence worldwide. 18F-FDG PET/CT imaging has already established itself as a pivotal modality for staging, restating and response assessment in patients with carcinoma breast. The complex biology of this cancer is increasingly being decoded and various molecular targets have been identified and exploited for guiding the treatment at various time points during the course of the disease. We here depict a series of various metabolic and receptor targeting PET radiotracers in breast cancer patients which may help us understand the in vivo biology of this tumor.

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https://journals.lww.com/nuclearmed/Fulltext/2020/02000/Breast_Cancer_Imaging_With_PET_Based.29.aspx

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