High performances of (18)F-fluorodeoxyglucose PET-CT in cardiac implantable device infections: A study of 40 patients.

BACKGROUND: Cardiovascular implantable electronic devices (CIED) infections are life-threatening complications. The diagnosis can be difficult to establish. Our purpose is to evaluate the diagnostic value of (18)F-FDG PET. METHODS: Forty patients who received work-up for suspected CIED infection were retrospectively included (group 1) and compared with 40 controls (group 2); CIED patients were referred for oncologic PET. PET-CT data were blindly assessed. Interpretation was based on visual analysis of both attenuation-corrected and non-corrected images and a semi-quantitative analysis was performed. The gold standard was bacteriological data of explanted devices or clinical follow-up for at least 1 year. RESULTS: Infection was present in 18 out of 40 patients of group 1. Sensitivity, specificity, positive predictive value, and negative predictive value of PET-CT were 83%, 95%, 94%, and 88%, respectively. Accuracy was 90%. PET-CT revealed the presence of additional pathological hypermetabolic foci in 28% of cases. PET-CT was negative at implanted devices in all patients of group 2. CONCLUSION: (18)F-FDG PET-CT is helpful in the work-up of suspected CIED infections. It is a potential tool to make the accurate diagnosis of CIED infection and to assess the extent of infection. The promising results in this indication need to be validated in a prospective multicenter study.

Dual-energy CT perfusion and angiography in chronic thromboembolic pulmonary hypertension: diagnostic accuracy and concordance with radionuclide scintigraphy.

OBJECTIVES: To evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) perfusion and angiography versus ventilation/perfusion (V/Q) scintigraphy in chronic thromboembolic pulmonary hypertension (CTEPH), and to assess the per-segment concordance rate of DECT and scintigraphy. METHODS: Forty consecutive patients with proven pulmonary hypertension underwent V/Q scintigraphy and DECT perfusion and angiography. Each imaging technique was assessed for the location of segmental defects. Diagnosis of CTEPH was established when at least one segmental perfusion defect was detected by scintigraphy. Diagnostic accuracy of DECT perfusion and angiography was assessed and compared with scintigraphy. In CTEPH patients, the per-segment concordance between scintigraphy and DECT perfusion/angiography was calculated. RESULTS: Fourteen patients were diagnosed with CTEPH and 26 with other aetiologies. DECT perfusion and angiography correctly identified all CTEPH patients with sensitivity/specificity values of 1/0.92 and 1/0.93, respectively. At a segmental level, DECT perfusion showed moderate agreement (κ = 0.44) with scintigraphy. Agreement between CT angiography and scintigraphy ranged from fair (κ = 0.31) to slight (κ = 0.09) depending on whether completely or partially occlusive patterns were considered, respectively. CONCLUSIONS: Both DECT perfusion and angiography show satisfactory performance for the diagnosis of CTEPH. DECT perfusion is more accurate than angiography at identifying the segmental location of abnormalities. KEY POINTS: • Chronic thromboembolic pulmonary hypertension (CTEPH) is potentially treatable by surgery. • Dual-energy computed tomography (DECT) allows angiography and perfusion using a single acquisition. • Both DECT perfusion and angiography showed satisfactory diagnostic performance in CTEPH. • DECT perfusion was more accurate than angiography in identifying segmental abnormalities.

Crowned dens syndrome diagnosed on ¹8F-FDG PET/CT.

An 87-year-old woman with corticosteroid-resistant polymyalgia rheumatica underwent ¹8F-FDG PET/CT for suspected giant cell arteritis or neoplastic disease. FDG uptake in the immediate vicinity of the odontoid process, with a crownlike calcification, was identified on the CT scan on the posterior side of the dens, thus confirming the diagnosis of crowned dens syndrome. Because this rare syndrome is frequently misdiagnosed, nuclear physicians should be aware of the signs and symptoms of this condition, which may call for the use of PET/CT imagery.

Positron emission tomography in patients with suspected pacing system infections may play a critical role in difficult cases.

BACKGROUND: A pacemaker recipient may be hospitalized recurrently with an infection of unknown origin despite detailed investigations. OBJECTIVE: The purpose of this study was to investigate whether (18)F-fluorodeoxyglucose positron emission tomography/computerized tomography (FDG-PET/CT) scanning has a role in identifying pacing material infection in these difficult cases. METHODS: Ten patients who presented with fever of unknown origin despite detailed investigations including transesophageal echocardiography underwent FDG-PET/CT scanning. Identification of increased FDG uptake along a pacing lead prompted the removal of the entire pacing system, whereas in the absence of increased FDG uptake the pacing material was left in place. Forty control pacemaker recipients underwent FDG-PET/CT scanning as part of investigation of malignancy. RESULTS: Among the 40 patients in the control group, FDG-PET/CT scanning was normal in 37 (92.5%) patients. Among the 10 patients who presented with suspected pacing system infections, FDG-PET/CT scanning showed increased FDG uptake along a lead in six patients; as a result of this finding, these patients subsequently underwent complete removal of the implanted material. Cultures of the leads were positive in all six patients, confirming involvement of the leads in the infectious process. In the other four patients, the pacing system was left in place without objective signs of active lead endocarditis during follow-up. CONCLUSION: This study demonstrates the potential value of FDG-PET/CT scanning in the diagnosis of pacing lead endocarditis in difficult cases. Increased FDG uptake along a lead in this clinical context appears to be a reliable sign of active infection.