Neurolymphomatosis with Spinal Nerve Root Involvement Demonstrated on 18F-FDG PET/CT.

A 56 years old woman with a diagnosis of diffuse large B-cell lymphoma had dyspnea, weakness in the left upper extremity and vocal cord paralysis after chemotherapy. She underwent cervical, thoracal and lumbosacral magnetic resonance imaging (MRI) however findings on MRI could not entirely explain the symptoms of the patient. Therefore, the patient underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography and the scan revealed focal symmetrical 18F-FDG uptake on the cervical, thoracal and lumbal spinal nerve roots. Considering the symptoms of the patient and cerebrospinal fluid cytology findings, hypermetabolic spinal nerve roots were interpreted as lymphoma involvement.

Mass-like Appearance on 18F-FDG PET/CT: Cascade Stomach.

A 56-year-old female patient who had involuntary weight loss underwent 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for detection of malignancy. The scan revealed non-metabolic soft tissue density in the posterior wall of the stomach requiring endoscopy. Endoscopical examination was performed 9 days after PET/CT and cascade stomach was detected. Cascade stomach is a rare entity that can be diagnosed by radiographic barium evaluations and endoscopy, the appearance on CT is largely incidental and CT has rarely been relied on for the diagnosis. We present this incidental case of cascade stomach on PET/CT to be familiar with the appearance.

The Influence of Specific Activity on the Biodistribution of 18F-rhPSMA-7.3: A Retrospective Analysis of Clinical PET Data.

We investigated whether the time between synthesis and injection and the resulting decrease in specific activity affects the normal-organ and tumor uptake of the PSMA ligand 18F-rhPSMA-7.3 in patients with prostate cancer. Methods: The biodistribution of 18F-rhPSMA-7.3 on PET/CT scans obtained with a high specific activity (median, 178.9 MBq/µg; n = 42) and a low specific activity (median, 19.3 MBq/µg; n = 42) was compared. Results: Tracer uptake by the parotid gland, submandibular gland, and spleen was moderately but significantly lower in the low-specific-activity group than in the high-specific-activity group (median SUVmean, 16.7 vs. 19.2; 18.1 vs. 22.3; and 7.8 vs. 9.6, respectively). No other statistically significant differences were found for normal organs or tumor lesions. Conclusion: A 10-fold decrease in specific activity has only minor effects on the biodistribution of 18F-rhPSMA-7.3. These findings suggest that 18F-labeled PSMA ligands can be centrally produced and shipped to PET clinics in a similar way to 18F-FDG.

Incidental Finding of Colon Carcinoma Related to High Uptake in 18F-PSMA-1007 PET.

We present a 78-year-old man with suspicion of prostate cancer due to a PSA of 200 ng/mL, who underwent F-PSMA-1007 (prostate specific membrane antigen) PET/CT for primary staging. Besides heterogeneous uptake to the prostate, an increased PSMA uptake in the cecum was observed, located in the thickened cecal wall with suspicion of a secondary malignancy. Colonoscopic biopsy followed by hemicolectomy confirmed the diagnosis of colon adenocarcinoma. This case demonstrates the importance of bioptic workup of suspicious findings on PSMA PET/CT, which are unlikely to be related to prostate cancer as PSMA ligand uptake is not exclusively prostate cancer specific.

Heterogeneous 68Ga-Prostate-Specific Membrane Antigen Uptake in the Left Upper Abdomen: Mesenchymal Tumor.

A 50-year-old man with recently diagnosed prostate adenocarcinoma was referred for whole-body Ga-prostate-specific membrane antigen (PSMA) PET/CT scan for staging. Apart from some nonspecific findings, Ga-PSMA PET/CT revealed large soft tissue mass in the left upper abdomen showing heterogeneous tracer uptake. Histological examination of the mass was interpreted as gastrointestinal/extragastrointestinal stromal tumor by pathologists. Prostate-specific membrane antigen is considered specific for prostate cancer cells, although PSMA activity has been described in many other benign or malign conditions. That is why PSMA uptake in uncommon locations for prostate cancer metastasis must be considered for second malignancies or other benign conditions.

Hepatoblastoma Mimicking Hemangioma in Labeled Red Blood Cell Scintigraphy.

Although Tc red blood cell (RBC) scintigraphy is a very specific method to differentiate a hemangioma from other hepatic masses, several cases of false-positive Tc RBC scintigraphy have been previously reported throughout the literature. We report an additional case that presented in a 15-month-old boy with hepatoblastoma showing increased labeled RBC activity mimicking hemangioma.

Atypical Appearance on Thyroid Scintigraphy: Achalasia.

We report the case of a 49-year-old woman with achalasia in whom thyroid stimulating hormone supression was incidentally detected on routine blood tests and who therefore underwent thyroid scintigraphy. Thyroid scan demonstrated low intensity diffuse technetium Tc sodium pertechnetate accumulation inferior to thyroid gland. After correlating the images with her previous barium esophagogram, tracer accumulation caudal to thyroid gland was explained on the presumption of Tc sodium pertechnetate retention within the dilated esophagus.