Subdiaphragmatic gallstone mimicking hepatic malignancy on FDG PET/CT

Increased Prostate-Specific Membrane Antigen Uptake in a Gallbladder Stone

ABSTRACT

An Al 18F-prostate-specific membrane antigen (PSMA) Q PET/CT scan was performed in a 67-year-old man to identify any potential recurrent prostate cancer lesions, which revealed no recurrent or metastatic lesions. However, a large gallbladder stone with increased PSMA uptake was incidentally detected, which could be a potential pitfall in the interpretation of PSMA PET imaging.

Hepato-Biliary Imaging in an Acute Setting: Is There a Role for Nuclear Medicine?

Nuclear medicine (NM) is not commonly considered as a first-line imaging modality in hepato-biliary (HB) emergencies. The aim of this review is to provide an update on the potential of NM for the imaging of HB emergencies. 99mTc-HIDA scintigraphy showed high diagnostic accuracy for acute cholecystitis, thus being particularly useful in patients at high-risk for surgery due to comorbidities and with no clear findings at US or CT. Although limitedly explored, White blood cell (WBC) scan might have a role in case of acute pancreatitis, especially for the imaging of pancreatic leukocyte infiltration and the prediction of pancreatic necrosis. Scientific literature on 18F-FDG-PET/CT in HB acute disease mainly consists of case reports or case series, describing incidental findings in oncological PET/CT scans. In patients with obstructive jaundice, PET/CT has been proposed to disclose and characterize occult tumoral etiology. Further studies are needed to evaluate the clinical usefulness of the various NM approaches in HB acute settings, particularly with respect to the emerging new technologies (eg, PET/MRI) and radiopharmaceuticals.

Spilled gallstone mimicking metastasis from cervix cancer on positron emission tomography – computed tomography

BACKGROUND

Spilled gallstones from previous cholecystectomy is not an uncommon situation. It may further mimic neoplastic disease and can be misled by fluorine 18 fluorodeoxyglucose position emission tomography with computed tomography ([18F]FDG PET/CT).

CASE SUMMARY

A 63 year-old patient was diagnosed with a cancer of the cervix. Pretreatment [18F]FDG PET/CT showed a peritoneal lesion suspicious for metastasis. Surgical exploration and histologic examination revealed the lesion to be a spilled gallstone from a previous cholecystectomy.

CONCLUSION

[18F]FDG PET/CT carries pitfalls since benign conditions such as intraperitoneal gallstones may be confused as malignant lesions. This case highlights the importance to be aware of the possible implications of dropped gallstones for the future, minimize its occurrence, and make all efforts to properly evaluate cancer staging, particularly for the cervix cancer.

High (18)F-FDG uptake in urinary calculi on PET/CT: An unrecognized non-malignant accumulation

AIM

To assess the high (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in urinary calculi on positron-emission tomography/computed tomography (PET/CT).

METHODS

In this study, (18)F-FDG PET/CT examinations were retrospectively reviewed from November 2013 to February 2016 in a single center, and patients with high (18)F-FDG uptake in urinary calculi were identified. The following data were collected from each patient, including age, sex, primary disease, method to verify the urinary calculus, and imaging characteristics of the calculus.

RESULTS

A total of 2758 PET/CT studies (2567 patients) were reviewed, and 52 patients with urinary calculi were identified, in which 6 (11.5%, 6/52) patients (5 males, 1 female, age 34-73 years, median age 60.5 years) demonstrated high (18)F-FDG uptake in the urinary calculi. Among the 6 patients, 3 patients had bladder calculi, 2 patients had renal calculi, and 1 patient had both bladder and renal calculi. The size of the urinary calculi varied from sandy to 19mm on CT. The maximal Hounsfield units of the calculi ranged from 153 to 1078. The SUVmax of the calculi on the routine PET/CT scan ranged from 11.7 to 143.0. Delayed PET/CT scans were performed on 4 patients, which showed the calculi SUVmax increasing in 2 patients, while decreasing in the other 2 patients. One patient with bladder calculus underwent a follow-up PET/CT, which showed enlargement of the calculus as well as the increased SUVmax.

CONCLUSION

This study shows an uncommon high (18)F-FDG uptake in urinary calculi. Recognition of this non-malignant accumulation in urinary calculi is essential for correct interpretation of PET/CT findings.