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Biomedical subjects

Alan D Waxman

Publications and source records attributed to Alan D Waxman.

3 recordsLinked to original sources
PubMed2003

Thyroid stunning.

Debates regarding thyroid stunning-a phenomenon whereby a diagnostic dose of radioiodine decreases uptake of a subsequent therapeutic dose by remnant thyroid tissue or by functioning metastases-have been fueled by inconsistent research findings. Quantitative studies evaluating radioiodine uptake and qualitative studies using visual observations both compare thyroid function on the diagnostic scan (DxSCAN) versus the posttreatment whole-body scan (RxWBS). The variability of findings may be the result of a lack of consensus in clinical nuclear medicine regarding many parameters of radioiodine usage including the need to obtain a pretreatment diagnostic scan, appropriate therapeutic dose, time between therapy dose administration and DxSCAN, and how successful ablation is measured. In the studies considered in this review, those that used (123)I rather than (131)I for DxSCAN, allowed less time to elapse between diagnostic and therapy dose, and more time between therapy dose and RxWBS (at least 1 week), did not observe stunning. However, groups that recognized stunning did not demonstrate any difference in outcomes (determined by successful first-time ablation). Whether stunning is a temporary phenomenon whereby stunned tissue eventually rejuvenates, or whether observed stunning actually constitutes "partial ablation," is yet to be delineated.

Dose-Response Relationship, Drug↗
PubMed2002

Whole-body (18)F-FDG PET identifies high-risk myeloma.

UNLABELLED: The purpose of this study was to evaluate the clinical utility of whole-body PET with (18)F-FDG in patients with multiple myeloma and related monoclonal diseases. METHODS: Between July 1, 1996, and July 2000, 98 (18)F-FDG PET scans were obtained for 66 patients, with 25 patients having 2 or more scans. The results were compared with routine clinical and staging information, including CT and MRI scans, as indicated. Of the 66 patients, 16 had previously untreated active myeloma, 14 had monoclonal gammopathy of undetermined significance (MGUS), 10 had disease in remission, and 26 had relapsing disease. RESULTS: Negative whole-body (18)F-FDG PET findings reliably predicted stable MGUS. Of the 14 MGUS patients with follow-up of 3-43+ mo, myeloma has developed in only 1 (7%), at 8 mo. Conversely, the 16 previously untreated patients with active myeloma all had focal or diffusely positive scan findings. Four (25%) of 16 previously untreated patients with positive (18)F-FDG PET findings had negative full radiologic surveys. Another 4 (25%) of 16 patients had focal extramedullary disease. This was confirmed by biopsy or other imaging techniques. Extramedullary uptake also occurred in 6 (23%) of 26 patients with relapse. This extramedullary uptake was a very poor prognostic factor both before treatment and at relapse. For example, median survival was 7 mo for patients with disease relapse. Persistent positive (18)F-FDG PET findings after induction therapy predicted early relapse. In 13 (81%) of 16 patients with relapsing disease, new sites of disease were identified. The (18)F-FDG PET results were especially helpful in identifying focal recurrent disease in patients with nonsecretory or hyposecretory disease amenable to local irradiation therapy, which was used in 6 patients. CONCLUSION: Whole-body (18)F-FDG PET provides important prognostic information, which is clinically useful and complementary to conventional methods of evaluating plasma cell disorders. (18)F-FDG PET is a unique tool for evaluation of nonsecretory myeloma. Residual or recurrent disease after therapy, especially extramedullary disease, is a poor prognostic factor.

Adult↗