[Clinical evaluation of 23 children with neuroblastoma. The experience of a single institution]. / Les neuroblastomes de l'enfant. A propos de 23 cas.

In this retrospective study, we analyse epidemiology, clinical symptoms and therapeutic results in a group of 23 children with neuroblastoma. Half of them were less than 2 years of age; in 19 of 23, the primitive tumour was abdominal; 35% of them were initially metastatic. The overall survival was 83% at 5 years and the event free survival, 75% at 5 years. Pronostic factors are age, extension of the disease at diagnosis, biologic parameters and genetic study of the neuroblast cells (amplification of N-myc oncogen). Our study shows the deleterious effect of bone lesions.

18FDG-PET for the assessment of primary head and neck tumors: clinical, computed tomography, and histopathological correlation in 38 patients.

OBJECTIVES: To evaluate the clinical usefulness of FDG-PET (fluoro-2-deoxy-glucose-positron emission tomography) in the detection of lymph node involvement and recurrences in patients with head and neck cancer. STUDY DESIGN: Retrospective review of 38 patients with biopsy-proven head and neck cancers who underwent clinical, computed tomography (CT), and FDG-PET examinations. Twenty-five patients were studied prior to therapy and 13 patients were evaluated for disease recurrence. METHODS: All patients were operated and clinical data, CT, and FDG-PET results were correlated with histopathological findings. RESULTS: All primary tumors in 25 patients were detected, with the exception of one small superficial localization of the epiglottis. Histopathological examination showed lymph node involvement in 10 patients; PET detected lymph node involvement in five. FDG-PET found one case of nodal disease not identified by clinical and CT examination. With so few cases, this could be anecdotal. Five false-negative results (microscopic lymph node involvement) and two false positives were noted. Twelve of 13 patients with recurrent disease were correctly identified with FDG-PET. FDG-PET was the only imaging technique to identify local recurrence in two patients and lymph node involvement in two others. One false-positive result occurred in a patient with a foreign body granuloma. CONCLUSIONS: FDG-PET is a useful diagnostic modality for the detection of recurrent tumors and, in selected cases, precise lymph node involvement. The best way to further investigate the utility of clinical FDG-PET is in the follow-up of treated patients.

Quantitative evaluation of myocardial single-photon emission tomographic imaging: application to the measurement of perfusion defect size and severity.

A new method is described for precise quantitative analysis of the relative three-dimensional distribution of myocardial tracers. The system uses a 360 degrees elliptical sampling of radial slices to create activity profiles. These are then positioned onto a common centre at the same angular coordinates as the corresponding radial slice reconstruction planes to generate a two-dimensional polar summary display. Abnormal distribution is then identified by automatic comparison of the patient polar map with the threshold of a normal database defined on a pixel by pixel basis as the normal mean -2.5 SD. Our stress and rest databases currently comprise 34 and 24 studies for sestamibi and tetrofosmin respectively. The present method differs from currently available software in two major respects. First, radial slices are used rather than short-axis slices to minimize operator intervention and to allow quantitative evaluation of the left ventricle volume independent of the heart size and without truncation, in particular near the apex and at the base. This sampling scheme also results in a more homogeneous and sampling-independent partial volume effect. Secondly, quantitative analysis is improved by calculating perfusion defect severity, extent and size in a precise manner. Severity is evaluated relative to a standardized background measurement and to the mean normal value rather than to the threshold value. This parameter was underestimated up to a defect extent of 32 cm2 in our phantom studies. Calculation of defect extent takes into account the surface distortion resulting from planar projection by using pixel by pixel weighted factors but it is otherwise overestimated as a result of the limited resolution of the imaging system. Integrating defect severity and extent, our hypoperfusion index appeared to accurately estimate the true defect size in our phantom model (r=0.993). The reproducibility of analysis was 6.24% in phantom studies and 3.10% in patient studies including repeated acquisitions. Applied to a well-documented population of 80 patients, this method resulted in an 86% sensitivity and a 78% specificity for overall coronary artery disease detection with reference to the angiographic data.

Tomographic myocardial imaging with technetium-99m tetrofosmin. Comparison with tetrofosmin and thallium planar imaging and with angiography.

Technetium-99m tetrofosmin is a new myocardial imaging agent with improved handling and kinetic characteristics. The purpose of this study was to compare the ability of planar and SPECT Tc-99m tetrofosmin imaging with Thallium-201 planar data to detect coronary artery disease and individual vessel lesions ( > 50% diameter stenosis). Seventy-two patients with definite or suspected coronary artery disease were included. Sixty-three had angiographic evidence of coronary artery disease, among whom 42 had had a previous myocardial infarction, while 21 had not. The total number of diseased arteries was 111. Patients underwent symptom-limited treadmill or bicycle exercise to similar endpoints. Thallium and tetrofosmin images were analysed separately by consensus reading. Interpretation was made for five standard anatomical regions (anterior, septal, inferior, lateral and apex), classified into four categories (normal, reversible, fixed and mixed defects). Sensitivity and specificity to detect coronary artery disease were 71% and 78% for Thallium-201 vs 68% and 78% for tetrofosmin by planar imaging, and 87% and 89% for tetrofosmin by SPECT. The improved sensitivity of SPECT was confirmed both in patients with and without previous myocardial infarction. The sensitivity to detect individual vessel lesions was improved by SPECT (59% tetrofosmin SPECT vs 50% thallium planar and 51% tetrofosmin planar). Individual vessel lesion detection by SPECT was 50% for the left anterior descending coronary artery, 42% for the left circumflex and 86% for the right coronary artery. This study confirms the value of technetium-99m tetrofosmin as a myocardial imaging agent. Improvements in diagnosis and in evaluating extent of disease can be expected from using SPECT.