11C-methionine PET/CT after inconclusive 99mTc-MIBI-SPECT/CT for localisation of parathyroid adenomas in primary hyperparathyroidism

AIM

To investigate the efficacy of PET/CT with 11C-methionine for localizing parathyroid adenomas in patients with suspected primary hyperparathyroidism and inconclusive results of cervical ultrasonography and 99mTc-MIBI-SPECT/CT.

PATIENTS, METHOD

Retrospective analysis of imaging data of 18 patients and correlation with clinical outcome, in particular intraoperative findings and histopathology of excised tissue.

RESULTS

12 of 18 patients received surgery. In 10 patients single parathyroid adenomas were found (diameter: 5-20 mm), 2 patients presented parathyroid hyperplasia (5 excised hyperplastic glands (diameter: 2-12 mm). PET/CT correctly localized all adenomas and 1 of 5 hyperplastic glands. The sensitivity per patient was 91.7% (11 of 12), the sensitivity per lesion 73.3% (11 of 15). All lesions missed by PET/CT had a size smaller than 9 mm and a volume of less than 0.2 ml. In 6 patients no surgery was performed. Five of them had a negative or atypical PET/CT. Further follow-up indicated familial hypocalciuric hypercalcemia in 3 of them (thus, PET/CT true negative), in the remaining 2 patients no validation is available. One patient with 2 highly suggestive lesions rejected surgery so far.

CONCLUSION

PET/CT with 11C-methionine is a very sensitive method for the detection of parathyroid adenomas, even if they are too small to be visualized by 99mTc-MIBI-SPECT/CT.

Assessment of relapse in patients with peritoneal carcinomatosis after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy using F-18-FDG-PET/CT

PURPOSE

In patients with peritoneal carcinomatosis (PC), cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is an evolving therapeutic approach with curative intention. The differentiation between posttherapeutic findings after HIPEC and relapse of PC is challenging. We evaluated the diagnostic value of F-18-FDG-PET/CT in patients with relapse of PC after HIPEC.

MATERIALS AND METHODS

36 patients with recurring PC after HIPEC were examined on a whole-body PET/CT system (44 examinations). The examination included 3 D F-18-FDG-PET and contrast-enhanced CT. Images were assessed by two experienced readers regarding the presence and the extent of PC using the peritoneal carcinomatosis index (PCI). Imaging results were correlated with surgical findings or follow-up.

RESULTS

Relapse was suspected in 40 of 44 examinations. Relapse was missed by F-18-FDG PET/CT in 4 patients and significantly underestimated in 8 patients. The diagnostic accuracy for the detection of PC on a patient basis was 91 %, the sensitivity was 91 % and the positive predictive value was 100 %. The mean PCI was 11.4 ± 11.9 for PET/CT, 8.4 ± 10.3 for CT and 16.6 ± 15.0 in the case of surgical exploration. The extent of PC was underestimated by PET/CT and even more by CT alone (p < 0.05).

CONCLUSION

The diagnostic value of F-18-FDG PET/CT after cytoreductive surgery and HIPEC in the detection of recurring PC is superior to contrast-enhanced CT. However, the quantification of the extent of PC is limited due to post-therapeutic tissue alterations.

KEY POINTS

• Imaging of recurrent PC after HIPEC is challenging due to posttherapeutic tissue alterations.• The extent of recurrent PC after HIPEC is systematically underestimated by F-18-FDG PET/CT.• F-18-FDG PET/CT provides improved sensitivity for recurrent PC compared to contrast-enhanced CT.• The correlation of the extent of recurrent PC depicted by F-18-FDG PET/CT and surgical exploration is better than that of contrast-enhanced CT and surgical exploration.

Clinical outcomes of remission induction therapy for severe antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

To evaluate the reasons that complete remission is not achieved or maintained with original treatment in some patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) treated with rituximab (RTX) or with cyclophosphamide/azathioprine (CYC/AZA).

METHODS

The Rituximab in AAV trial was a randomized, double-blind, placebo-controlled trial comparing the rate of remission induction among patients treated with RTX (n = 99) and patients treated with CYC followed by AZA (n = 98). Glucocorticoids were tapered over a period of 5 months. The primary outcome measure was lack of disease activity without glucocorticoid treatment at 6 months. To determine the most important reason for failure to achieve the primary outcome, 7 hierarchical categories of reasons were defined retrospectively (uncontrolled disease, adverse event leading to therapy discontinuation, severe flare, limited flare, Birmingham Vasculitis Activity Score for Wegener's Granulomatosis >0, prednisone treatment at any dosage, and other).

RESULTS

Although remission (lack of disease activity) was achieved in 170 of the 197 patients (86%) in the first 6 months, the primary outcome measure was not achieved in 42%. There were 3 deaths. Twenty-four percent of the patients failed to achieve the primary end point due to active disease: 10 (5%) experienced uncontrolled disease in the first month and 37 (19%) experienced flares after initial improvement. In the majority of such patients, treatment with blinded crossover or according to best medical judgment led to disease control. Ninety-one percent of patients who had uncontrolled disease or experienced a severe flare had proteinase 3 (PR3)-ANCA. When patients with uncontrolled disease were excluded from analysis, those who were PR3-ANCA positive were found to experience fewer flares when treated with RTX compared to CYC/AZA (8 of 59 [14%] versus 20 of 62 [32%]; P = 0.02). Neither ANCA titers nor B cell counts predicted disease flare.

CONCLUSION

Current treatment regimens are largely successful in controlling AAV, but in approximately one-fourth of patients, active disease persists or recurs in the first 6 months despite treatment. PR3-ANCA positivity is a risk factor for recurrence or persistence of severe disease. ANCA titers and B cell detectability are poor predictors of both disease relapse and disease quiescence in the first 6 months.