Pierre Weinmann

Functional imaging in extrapulmonary sarcoidosis: FDG-PET/CT and MR features.

Abstract Sarcoidosis is a multiorgan granulomatous disease of unknown etiology that primarily involves the lungs and the lymphatic system. Extrapulmonary sarcoidosis is common, occurring in 30 to 50% of patients. In this review, we describe and illustrate the role of 18F-FDG PET/CT and MR imaging in patients with extrapulmonary sarcoidosis. FDG-PET/CT and MR can improve the accuracy of the diagnosis of extrapulmonary involvement, specify the respective contributions of active and fibrotic components of lesions, guide the selection of the biopsy site, provide prognostic information, and guide therapeutic management. We focus on suggestive patterns that help to improve lesion characterization, especially when these lesions are clinically occult. In cardiac sarcoidosis, the combined use of FDG-PET/CT and cardiac MR may provide optimal detection of the disease by enabling the differentiation between patients with active granulomatous inflammation and those with fibrous lesions. In cases with central nervous system involvement, the T2 hypointensity of the dural and parenchymal lesions is helpful for identifying sarcoidosis. Granulomatous bone marrow infiltration in the axial skeleton can be sensitively detected by both FDG-PET/CT and MR. Muscular sarcoidosis can have a characteristic appearance with the “dark star” sign on MR and a thick linear FDG uptake that predominantly involves the lower legs, designated as the “tiger man” sign. Extrathoracic lymphadenopathy is commonly observed on FDG-PET/CT imaging; however, its features are not specific, and the differentiation of extrathoracic lymphadenopathy from metastatic disease, tuberculosis, or lymphoma may be difficult. Familiarity with the functional imaging features in extrapulmonary sarcoidosis in various anatomical locations plays a crucial role in the diagnosis and management of patients.

Tracheobronchial FDG uptake in primary amyloidosis detected by PET/CT.

Tracheobronchial amyloidosis is a rare manifestation of the disease and has never been described with FDG PET/CT. In this study, we report a case of a 70-year-old man with increasing dyspnea, a right pleural effusion, a tracheobronchial circumferential wall thickening, and a mediastinal fat infiltration on CT scan. FDG PET/CT revealed intense tracheobronchial uptake associated with mediastinal and intra-abdominal fat uptake. Bronchoscopy and mediastinoscopy with biopsies confirmed the diagnosis of primary amyloidosis and excluded malignancy. FDG PET/CT could be useful for the evaluation of tracheobronchial amyloidosis metabolic activity and follow-up.

Clinical validation of simultaneous dual-isotope myocardial scintigraphy

Abstract. Simultaneous dual-isotope (rest thallium-201/stress technetium-99m sestamibi) myocardial single-photon emission tomography (SPET) would be an ideal procedure; however, 99mTc cross-talk on the 201Tl window hampers its routine use. Photon energy recovery (PER) is a spectral deconvolution technique validated for scatter and cross-talk removal in phantom studies and a limited series of patients. In this study we aimed to validate the technique in 295 patients within a context of clinical routine practice. Conventional separate rest 201Tl myocardial SPET data sets were visually compared with simultaneous dual-isotope data sets corrected by PER. Conventional separate rest 201Tl data sets were identical to dual PER-corrected 201Tl data sets in 173 (58.6%) patients. As dual PER 201Tl data sets are corrected for 99mTc cross-talk but also for 201Tl scatter, they were compared with separate rest 201Tl data sets corrected by PER in the 122 discordant patients. No difference was found in 77 (26.1%) patients. In 26 (8.8%) patients, the difference consisted in the presence of a defect on dual PER 201Tl data sets only, mirroring an ischaemic defect on 99mTc-sestamibi data sets. This difference can be attributed to the influence of stress on the kinetics of 201Tl injected at rest. In the remaining 19 (6.4%) patients, the difference between separate and simultaneous PER-corrected data sets was scored as mild in 11 and moderate in eight patients and seemed to be related to multiple methodological factors. It is concluded that PER correctly removes 99mTc cross-talk. With the addition of an appropriate attenuation correction, the PER technique may allow the routine use of simultaneous dual-isotope myocardial scintigraphy in the near future.

Visualization of amyloid arthropathy in light-chain systemic amyloidosis on F-18 FDG PET/CT scan.

We report a case of 63-year-old man with symmetrical joint swelling of the interphalangeal and metacarpal joints, associated with isolated hypogammaglobulinemia. Accessory glands biopsy revealed the presence of amyloidal deposits. PET/CT showed increased F-18 FDG activity in thickened soft tissues corresponding to amyloid arthropathy. Like multiple myeloma, PET/CT could be an interesting imaging in light-chain amyloidosis.

Effects of dipyridamole on left ventricular function.

BackgroundChanges induced by dipyridamole infusion on left ventricular function in healthy individuals have not been investigated by gated myocardial perfusion single photon emission computed tomographic (SPECT) imaging.Methods and ResultsThis study examined the amplitude and duration of changes induced by dipyridamole infusion on left ventricular function as assessed by technetium 99m sestamibi gated SPECT in 18 subjects with a low likelihood of coronary artery disease. Twenty mCi (740 MBq) of Tc-99m sestamibi were injected at rest. Three different consecutive gated SPECT images were performed 60 minutes later: baseline at rest, during the infusion of 0.76 mg/kg of dipyridamole, and 1 hour later. No patient received aminophylline. Left ventricular ejection fraction (LVEF), end-diastolic volume, and end-systolic volume were automically computed. Heart rate (HR) and blood pressure were regularly monitored.Mean LVEF was 63.2%±8.0% baseline at rest, increased to 73.8%±8.2% (P=.0001) during dipyridamole infusion, and returned to baseline values (63.0%±7.5%) 1 hour later. End-diastolic volume did not vary significantly, and end-systolic volume decreased (from 32.2±19.5 to 26.6±17.9 u, P=.002) and returned to baseline values (32.7±15.6 u) 1 hour later. Dipyridamole induced moderate HR acceleration (from 80.2±15.0 to 96.5±9.6 beats/min, P<.001) and a slight decrease in diastolic blood pressure (from 80.6±8.1 to 70.1±9.0 mm Hg, P<.001). However, 1 hour later, HR and blood pressure had returned to baseline values.ConclusionsDipyridamole increases LVEF and HR and decreases diastolic blood pressure slightly in healthy individuals. Because dipyridamole gated SPECT imaging acquisition is usually started 60 minutes after dipyridamole infusion, LVEF is in fact estimated at rest.

Dual-isotope myocardial imaging: feasibility, advantages and limitations

Two hundred and thirty-one patients underwent dual-isotope myocardial imaging (rest thallium-201 followed by stress technetium-99m sestamibi). The feasibility of the procedure was excellent: camera scheduling flexibility was improved and the duration of the procedure was less than that of a classical stress-redistribution procedure. Interpretation of defects due to image attenuation was facilitated by the different attenuation properties of 201Tl and 99mTc-sestamibi in 11 of 19 patients. 210Tl cross-over on 99mTc was found to be 15% ± 3% with doses of 201Tl and 99mTc-sestamibi of 3 and 10 mCi, respectively, and 7% ± 2% with doses of 3 and 20 mCi. This protocol should preferentially be reserved for patients with a history of myocardial infarction and/or a basal left ventricular dysfunction, in whom assessment of myocardial viability is of major interest. Extensive clinical validation of the dual-isotope procedure is required and optimal acquisition and reconstruction parameters should be established.

Coronary spasm induced by dipyridamole during a myocardial scintigraphy

A 59-year-old male underwent a dipyridamole myocardial scintigraphy. During dipyridamole infusion, a marked ST-segment elevation was observed in the inferior leads. After aminophylline injection, a short burst of ventricular tachycardia occurred, then the ST-segment elevation disappeared. The myocardial scintigraphy was consistent with myocardial ischemia of the inferior wall. The coronary angiography revealed no significant coronary lesion. Coronary spasm induced by dipyridamole remained the most probable mechanism for this complication.

Usefulness of Tomographic Versus Planar Lung Scintigraphy in Suspected Pulmonary Embolism in a Daily PracticeT

Objectives: Lung scintigraphy is non-diagnostic in most patients suspected of pulmonary embolism when performed in planar mode. Tomographic mode could improve lung scan performance but has not been rigorously assessed. In this study we assessed the usefulness of tomographic mode in patients with a non-diagnostic lung scan scintigraphy. Methods: pulmonary embolism was diagnosed or ruled out in consecutive patients with a non-diagnostic lung scan by the combination of a 4-slices computerized tomography and a lower-limb ultrasonography. Results given by reading the tomographic mode in ventilation/perfusion lung scan were compared to final diagnosis. Results: 142 out of 392 consecutive patients with a non-diagnostic planar lung scintigraphy were included while 47 were excluded, 45 because of contra-indication to contrast medium and 2 because of non-optimal opacification of pulmonary arteries. Ninety-five patients were evaluated. Pulmonary embolism was diagnosed in 20 (21%) patients and ruled out in 75 (79%). Concordance with final diagnosis was found in 77/94 (82%) patients. Tomographic mode was non-diagnostic in 1 (1%) patient. Tomographic mode sensitivity/specificity/accuracy were 0.79/0.83/0.80 respectively. Negative predictive value was 0.94. Discordances were related to single sub segmental or non-occluding segmental thrombus. Conclusion: Tomographic mode is diagnostic in nearly all patients and agreement with final diagnosis is found in the majority. Its excellent negative predictive value enables to rule out pulmonary embolism. Discordances were related to single sub segmental or non-occluding segmental thrombus which prognosis value remains to be established.

Diagnosis of synchronous isolated splenic metastasis from lung adenocarcinoma: complementary role of FDG PET/CT and diffusion-weighted MRI.

Isolated splenic metastasis is extremely rare. In this study, we report a case of a 52-year-old man referred for Pancoast Tobias Syndrome by which FDG PET/CT detected an isolated splenic metastasis. Diffusion-weighted MRI confirmed the isolated splenic lesion. A low apparent diffusion coefficient was consistent with a tumor lesion. CT-guided biopsy of both the lesions and histopathologic findings confirmed a lung adenocarcinoma with an isolated splenic metastasis. This case reveals a very rare occurrence of isolated splenic metastases in the context of lung cancer and illustrates the role of multimodality functional imaging for the early detection of uncommon metastasis.

New application of myocardial antimyosin scintigraphy: diagnosis of myocardial disease in polymyositis.

Heart disease is a rare but important complication of polymyositis. Diagnosis of myocardial disease is usually based on non-specific clinical, electrocardiographic, and echocardiographic data. This paper reports a case of polymyositis with myocardial disease diagnosed by myocardial imaging with radiolabelled antibody to myosin, a specific marker of the necrotic myocardial fibre.