Multiple endocrine neoplasia type 1 or 4: detection of hyperfunctioning parathyroid glands with 18F-fluorocholine PET/CT. Illustrative cases and pitfalls.

18F-fluorocholine (FCH) PET/CT is now well established to detect the hyperfunctioning parathyroid glands (HFPTG) in a case of sporadic primary hyperparathyroidism (pHPT), but only limited evidence is available about the utility of FCH PET/CT to detect the HFPTG in patients with multiple endocrine neoplasia (MEN) type 1 or 4. The pHPT in this context frequently consists in a multiglandular disease with small hyperplastic glands rather than adenomas, which is challenging for imaging modalities. The data of patients with MEN1 or MEN4 after parathyroidectomy referred to FCH PET/CT for presurgical localization of HFPTG were retrospectively reviewed, including follow-up after parathyroidectomy, in search for diagnostic performance and for potential pitfalls. In the present cohort, 16 patients referred to FCH PET/CT as part of their initial pHPT work-up were subsequently operated, 44 abnormal parathyroid glands (PT) were resected, of which 32 (73%) had been detected on FCH PET/CT and 2 considered as equivocal foci. Nine patients referred to FCH PET/CT for recurrent pHPT who were subsequently operated, 14 abnormal PT were resected, all had been detected on FCH PET/CT. FCH PET/CT permitted a unilateral approach for PTx in 4 of them. In one patient with MEN4 and pHPT, the HFPTG could not be visualized on FCH PET/CT but was localized by ultrasonography. Several causes of false positive or false negative results, incidental finding and pitfalls are listed and discussed. FCH PET/CT has a positive benefit/risk ratio in the detection of HFPTG in case of MEN1 (the data in MEN4 being currently very limited) with the most effective detection rate of current imaging modalities for HFPTG, few pitfalls, and an adequate impact on patient management compared to sesta MIBI SPECT and ultrasonography.

Value of 18F-FDG PET/CT imaging in the staging, restaging, monitoring of response to therapy and surveillance of uterine leiomyosarcomas.

OBJECTIVE: Leiomyosarcoma (LMS) is the most common subtype of uterine sarcomas. It is a rare and aggressive tumour. The aim of the present study was to assess the performance of fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT imaging in four clinical settings: initial staging, restaging, monitoring of response to therapy and post-therapy surveillance of uterine LMS. PATIENTS AND METHODS: A bicentric retrospective study was carried out on a group of 21 patients with uterine LMS for whom a total of 52 PET/CT scans were available in initial staging (n=11), restaging (n=11), monitoring of response to therapy (n=17) and post-therapy surveillance (n=13). Clinical (minimum 6 months after PET/CT scan) and/or imaging follow-up and pathology were used as the reference standard. RESULTS: In the initial staging, the sensitivity, specificity and accuracy of PET imaging were 80, 100 and 91%, respectively. In the restaging and monitoring of response to therapy, all these indices were 100%, whereas they were lower in post-therapy surveillance at 75, 100 and 85%, respectively, because of two false-negative results. False-negative lesions were an infracentimetric lung nodule in the initial staging and a peritoneal nodule that had increased in size between two PET/CT scans in post-therapy surveillance. PET-negative lesions were all identified on the computed tomography (CT) part of the PET/CT; thus, the performances of the exam improved to 100% on taking into account the CT component of the PET/CT. CONCLUSION: PET/CT imaging has a high diagnostic yield in the initial staging and restaging of uterine LMS, but seems less sensitive in post-therapy surveillance. Evaluation of the CT part improves the sensitivity of the PET scan. Thus, PET/CT imaging should be considered in patients presenting with LMS.

Diagnostic performance and impact on patient management of 68Ga-DOTA-TOC PET/CT for detecting osteomalacia-associated tumours.

PURPOSE: Oncogenic osteomalacia is an endocrine disorder induced by small benign tumours (TIO) producing excessive fibroblast growth factor-23 (FGF23). The only way of curing oncogenic osteomalacia is surgical resection of the culprit TIO, which is extremely difficult to detect using conventional imaging modalities due to its small size and variable location in the body. Since TIO frequently overexpress somatostatin receptors, a clinical utility of SPECT or PET with radiolabelled somatostatin analogues has been reported. Among them, 68Ga-DOTA-TOC has recently been granted a marketing authorization, facilitating its routine application. We report here the results of the first series evaluating the diagnostic performance of 68Ga-DOTA-TOC PET/CT in detecting TIO and its impact on patient management. METHODS: 68Ga-DOTA-TOC PET/CT and clinical and imaging data from 15 patients with clinical and biochemical signs of oncogenic osteomalacia were retrospectively reviewed. The 68Ga-DOTA-TOC PET/CT findings were compared with the results of post-surgical pathology and clinical and biochemical follow-up. RESULTS: 68Ga-DOTA-TOC PET/CT resulted in the detection of one focus suspicious for TIO in nine of 15 patients (60%), and a tumour was surgically removed in eight. Post-operative pathology confirmed a TIO in those eight patients whose symptoms diminished promptly and biochemical anomalies resolved. 68Ga-DOTA-TOC PET/CT sensitivity, specificity and accuracy were 73%, 67% and 71%, respectively. 68Ga-DOTA-TOC PET/CT findings affected patient management in 67% of cases. In particular, 68Ga-DOTA-TOC PET/CT was able to detect the TIO with a negative or a false-positive result of a previous 111In-pentetreotide SPECT/CT in 5/8 patients (63%) or a previous FDG PET/CT in 7/11 patients (64%). No close relationship was found between the positivity of 68Ga-DOTA-TOC PET/CT and the serum level of a biochemical marker. However, a true-positive result of 68Ga-DOTA-TOC PET/CT was obtained in only one patient with a non-elevated serum level of FGF23. CONCLUSION: 68Ga-DOTA-TOC PET/CT is an accurate imaging modality in the detection of TIO; in particular, it is worthwhile after failure of somatostatin receptor SPECT(/CT) or FDG PET/CT.

Brain (18)F-FDG, (18)F-Florbetaben PET/CT, (123)I-FP-CIT SPECT and Cardiac (123)I-MIBG Imaging for Diagnosis of a "Cerebral Type" of Lewy Body Disease.

A 67-year-old man was referred for fluctuating neuropsychiatric symptoms, featuring depression, delirious episodes, recurrent visual hallucinations and catatonic syndrome associated with cognitive decline. No parkinsonism was found clinically even under neuroleptic treatment. (18)F-FDG PET/CT showed hypometabolism in the posterior associative cortex including the occipital cortex, suggesting Lewy body dementia, but (123)I-FP-CIT SPECT was normal and cardiac (123)I-MIBG imaging showed no signs of sympathetic denervation. Alzheimer's disease was excluded by a normal (18)F-florbetaben PET/CT. This report suggests a rare case of α-synucleinopathy without brainstem involvement, referred to as "cerebral type" of Lewy body disease.

IgG4-Related Tubulointerstitial Nephritis Pattern in 18F-FDG PET/CT.

A 17-year-old adolescent girl was admitted with chronic arthralgia, Raynaud phenomenon, pericarditis, and evidences of chronic diffuse inflammation. F-FDG PET/CT scan was performed to search systemic vasculitis and showed diffuse moderate uptake in the kidneys. We suggested the existence of a nephritis, but the ultrasonography result was normal, and no treatment was introduced. Another F-FDG PET/CT scan was performed 7 months later to explore abdominal pain. It showed again diffuse intense uptake in both kidneys. A proteinuria was highlighted, and renal biopsy allowed to diagnose IgG4-related disease.

Detection of a right carotid focus of 18F-FDG predicted an ischemic stroke.

A 60-year-old woman was referred into our department for staging of an endometrial carcinoma. In addition to peritoneal and nodes metastases, F-FDG PET/CT showed a calcified plaque of the right carotid with focal uptake. One month later, the patient presented left hemiparesis, suggesting a right hemisphere stroke. MRI confirmed frontal infarction in the anterior cerebral artery territory. F-FDG is suggested to be a valuable tool to detect vessel wall inflammation; detection of focal arterial uptake on PET/CT suggests unstable plaque and requires urgent patient's management to prevent vascular events in a population already weakened by both disease and therapy.