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In comparison with conventional imaging, nuclear medicine offers an original metabolic approach for the assessment of the therapeutic response. Gallium 67, thallium 201, technetium 99m-labeled sestamibi and diphosphonates can be performed for therapeutic response assessment in lymphoma, brain and breast tumours, sarcoma, or bone metastasis. PET-CT facilities are now easily available in France and are ready to provide a new and accurate tool in oncology, specially for therapeutic evaluation. The procedure consists in the injection of fluor-18-fluoro-déoxyglucose (18FDG), an analogue of glucose, followed by a PET then a CT acquisition for FDG uptake abnormalities location. Therapeutic response is assessed by a decrease of 18FDG tumoral uptake between two consecutive studies. Methodology and interpretation criteria have been recently defined in international guidelines. 18FDG-PET-CT seems to be a valuable tool for therapeutic response assessment of patients with Hodgkin or non Hodgkin malignant lymphoma. Promising preliminary results have been recently published for lung, gastro-intestinal and head and neck cancers. PET-CT could also be able to predict the therapeutic response after the first courses of chemotherapy, allowing an early treatment optimization. Finally, new PET agents pave the way for molecular imaging with promising results in gene therapy and targeted treatment in oncology.

A 48-year-old man presented with impaired joint movement and buccofacial apraxia. The disease progressed for six years associating an akineto-hypertonic syndrome, marked anarthria, saliva incontinence, bi-opercular syndrome, bucco-facial apraxia, severe global gestual apraxia and a frontal syndrom. Oculo-motricity and gait were normal. Magnetic resonance imaging of the brain demonstrated fronto-parietal atrophy and HMPAO Tc99 tomography revealed hypoperfusion of the cortex clearly predominating in the left parietal region. These particular findings with predominantly intense joint involvement is similar to the clinical picture in corticobasal degeneration--subcortical signs (progressively uncontrollable hypertonia) together with cortical signs (severe gestual apraxia). The neuroradiological imaging and functional results also suggest a degenerative process.

Fourty-six patients suspected clinically of having a pulmonary embolism (PE) were investigated by angiopneumography (AGP) and perfusion (99m-Tc aggregates) and ventilation (99m-Tc colloid) scintigraphy (SPV Tc). Findings were assessed under blind conditions. A positive diagnosis of pulmonary embolism was made in 19 patients. The SPV Tc was considered as positive if perfusional deficiencies were greater than ventilatory defects, and this was evaluated as such in 23 cases (19 true and 4 false positives). False negatives were not observed. The 4 false positive results corresponded to scintigraphic anomalies suggestive of pulmonary emboli subsegmental in size; true positives were either subsegmental (8), segmental (6) or lobar (5). Sensitivity of the SPV Tc wis therefore 100%; its specificity, all results considered was 76%, but was 100% if only images of lobar or segmental lesions are considered.

Bone uptake of 99 m Tc diphosphonate may allow early diagnosis of renal osteodystrophy. Our study deals with 53 patients treated by repeated hemodialysis and reveals scanning abnormalities in 75% of them. Bone scanning provides information which are not visualized radiologically, especially scattered or located pulmonary calcifications (15% in our series). It is valuable in the follow-up of bone changes and is part of the necessary investigations before carrying out parathyroidectomy.

The authors relate 7 cases of hematogenous osteomyelitis in children where skeletal scintigraphy with TC 99m diphosphonate was said as normal. They analyse the lack of positive radionuclide findings; misinterpretation, abnormal tracer accumulation which probably relates to regional hyperemia, transient area of discreased uptake of the tracer in the early phase of the disease and real negative bone scan; these cases are rare; when there is a high suspicion of osteomyelitis in spite of a normal bone scan Gallium imaging may be helpful.

The authors report 5 observations of young adults, 3 teen-agers and 2 children suffering from algodystrophy, and in whom isotopic exploration of the skeleton disclosed a clear bony hypofixation during the entire evolution. These observations confirm their 1981 work concerning a young adult suffering from algodystrophy with isotopic bony hypofixation. Recent Canadian and American studies emphasize also the frequency of isotopic hypofixation in children algodystrophy. It seems, therefore, that isotopic bony hypofixation (linked perhaps to a decreased blood flow), is rather specific of algodystrophy in young subjects.