Evaluating bone marrow metastasis of neuroblastoma with iodine-123-MIBG scintigraphy and MRI.

Of 10 patients with neuroblastoma who had both 123I-MIBG scintigraphy and MRI at diagnosis, four presented with bone marrow metastasis that was diagnosed by both imaging modalities and confirmed by bone marrow biopsy and smears. This report focuses on the follow up of the four patients with bone marrow metastasis. MIBG scintigraphy and MRI were concordant in two patients, a case of normalization and a case of relapse in the seventh dorsal vertebra confirmed by surgical biopsy. The last two patients presented a normalized MIBG scan for marrow infiltration after chemotherapy but persistent abnormal MRI signal of several vertebrae, suggesting marrow infiltration, up to 27 mo after the end of chemotherapy in one case. In the second patient, MRI bone marrow aspect returned to normal 4 mo after the end of chemotherapy. Bone marrow biopsy remained negative in these two MIBG-negative patients. These cases suggest that in presence of complete normalization of the MIBG scan after chemotherapy, the persistence of a hypointense signal on bone marrow on T1WI does not necessarily indicate persistence of disease but may be due to delayed normalization. Therefore, attention must be paid to the delay of signal normalization on MRI (which can be as long as more than 2 yr after the end of chemotherapy) in order to avoid false-positive interpretation.

Left bundle branch block and coronary artery disease: accuracy of dipyridamole thallium-201 single-photon emission computed tomography in patients with exercise anteroseptal perfusion defects.

BACKGROUND: Reduced septal or anteroseptal uptake of thallium-201 during exercise is frequently observed in patients with left bundle branch block (LBBB) even in the absence of left anterior descending (LAD) coronary artery disease. The purpose of this study was to evaluate prospectively the accuracy of dipyridamole 201Tl single-photon emission computed tomography (SPECT) in detecting LAD coronary artery disease in patients with LBBB and septal or anteroseptal perfusion defects on exercise 201Tl SPECT. METHODS AND RESULTS: Twelve consecutive patients (10 men and two women) with complete LBBB and septal or anteroseptal perfusion defects on exercise 201Tl SPECT underwent dipyridamole 201Tl SPECT. The delay between dipyridamole and exercise was 2 to 30 days. Coronary angiography was performed during this period in all patients. Six (50%) of 12 patients with exercise perfusion defects showed normal perfusion after dipyridamole; all had normal coronary angiograms. The remaining six patients also had positive results of dipyridamole studies, two with moderate and four with severe septal or anteroseptal perfusion defects. Coronary angiography showed significant (> 50%) LAD coronary artery stenosis in three patients; three patients with severe septal or anteroseptal perfusion defects after dipyridamole had normal coronary angiograms. Neither the evaluation of apical involvement nor the presence of dilated ventricles, decreased left ventricular ejection fraction, or wall motion abnormalities could help to identify (or explain) false-positive results. CONCLUSION: This study confirms that dipyridamole is more accurate than exercise in excluding LAD coronary artery disease. However, there are still false-positive results and the severity of the septal or anteroseptal perfusion defect does not add additional information to identify LAD coronary artery disease. Coronary angiography is thus necessary for positive dipyridamole study results to identify coronary artery disease as a major prognostic factor in patients with LBBB.

Diagnosis and follow-up of neuroblastoma by means of iodine-123 metaiodobenzylguanidine scintigraphy and bone scan, and the influence of histology.

The purpose of this work was to compare technetium-99m-diphosphono-propanedicarboxylate (DPD) and iodine-123-metaiodobenzylguanidine (MIBG) scans in the diagnosis and follow-up of neuroblastoma, and to study the role of histological differentiation in the uptake of MIBG. The uptake of MIBG and of DPD were studied retrospectively in 27 patients with neuroblastoma (primary, residual and recurrent tumours as well as bone and bone marrow metastases). The findings were related to the histological classification of the tumours as neuroblastoma (N1), differentiating neuroblastoma (N2) or ganglioneuroblastoma (N3). Uptake of MIBG by the primary tumour occurred in 17 of 19 patients, either at diagnosis or during follow-up. There were only two false-negatives with MIBG, both of which were N3. Ten patients were studied preoperatively with both MIBG and DPD. The primary tumour showed MIBG uptake in nine of the ten and DPD uptake in eight of them. Thirty-five sites of cortical bone metastasis were shown in eight patients by both MIBG and DPD, 12 sites in seven patients by MIBG only and seven sites in five patients by DPD only. In 14 patients both MIBG and bone scan were negative. Overall, MIBG demonstrated more lesions than DPD. Retrospectively several hot spots seen only with the bone scan are to be considered as false-positive. The highest incidence of false-negative MIBG and bone scans was observed in ganglioneuroblastoma with a predominance of the more mature component (ganglioneuroma).