166Ho-DOTMP radiation-absorbed dose estimation for skeletal targeted radiotherapy.

166Ho-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene-phosphonate (DOTMP) is a tetraphosphonate molecule radiolabeled with 166Ho that localizes to bone surfaces. This study evaluated pharmacokinetics and radiation-absorbed dose to all organs from this beta-emitting radiopharmaceutical. METHODS: After two 1.1-GBq administrations of 166Ho-DOTMP, data from whole-body counting using a gamma-camera or uptake probe were assessed for reproducibility of whole-body retention in 12 patients with multiple myeloma. The radiation-absorbed dose to normal organs was estimated using MIRD methodology, applying residence times and S values for 166Ho. Marrow dose was estimated from measured activity retained after 18 h. The activity to deliver a therapeutic dose of 25 Gy to the marrow was determined. Methods based on region-of-interest (ROI) and whole-body clearance were evaluated to estimate kidney activity, because the radiotracer is rapidly excreted in the urine. The dose to the surface of the bladder wall was estimated using a dynamic bladder model. RESULTS: In clinical practice, gamma-camera methods were more reliable than uptake probe-based methods for whole-body counting. The intrapatient variability of dose calculations was less than 10% between the 2 tracer studies. Skeletal uptake of 166Ho-DOTMP varied from 19% to 39% (mean, 28%). The activity of 166Ho prescribed for therapy ranged from 38 to 67 GBq (1,030-1,810 mCi). After high-dose therapy, the estimates of absorbed dose to the kidney varied from 1.6 to 4 Gy using the whole-body clearance-based method and from 8.3 to 17.3 Gy using the ROI-based method. Bladder dose ranged from 10 to 20 Gy, bone surface dose ranged from 39 to 57 Gy, and doses to other organs were less than 2 Gy for all patients. Repetitive administration had no impact on tracer biodistribution, pharmacokinetics, or organ dose. CONCLUSION: Pharmacokinetics analysis validated gamma-camera whole-body counting of 166Ho as an appropriate approach to assess clearance and to estimate radiation-absorbed dose to normal organs except the kidneys. Quantitative gamma-camera imaging is difficult and requires scatter subtraction because of the multiple energy emissions of 166Ho. Kidney dose estimates were approximately 5-fold higher when the ROI-based method was used rather than the clearance-based model, and neither appeared reliable. In future clinical trials with 166Ho-DOTMP, we recommend that dose estimation based on the methods described here be used for all organs except the kidneys. Assumptions for the kidney dose require further evaluation.     

Value of positron emission tomography in staging ocular adnexal lymphomas and evaluating their response to therapy.

BACKGROUND AND OBJECTIVE: An observational case series to assess the value of positron emission tomography (PET) in staging ocular adnexal lymphomas and evaluating their response to therapy. PATIENTS AND METHODS: The clinical records of 16 consecutive patients with ocular adnexal lymphoma for whom pretreatment and posttreatment PET scans and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) scans were available were compared. RESULTS: Pretreatment PET scans demonstrated fluorine 18-fluorodeoxyglucose (FDG) positive lesions in 15 orbits of 12 patients. In 1 patient with low-grade follicular lymphoma of the orbit, PET revealed an additional focus of lymphoma in the deltoid muscle that was missed on clinical examination and conventional radiography. All of the posttreatment PET scans showed complete resolution of FDG uptake, suggesting good response to therapy. However, posttreatment CT and MRI scans demonstrated residual masses in 3 patients. CONCLUSIONS: PET is valuable for initial staging of ocular adnexal lymphomas and may be a good adjunct to conventional imaging in evaluation of response to therapy.     

PolyA PCR amplification of cDNA from RNA extracted from formalin-fixed paraffin-embedded tissue.

RNA extraction still relies almost exclusively on the use of fresh or frozen tissue, limiting the number of samples that can be analyzed, and there is a growing need for means of global mRNA analysis of archived formalin-fixed paraffin-embedded tissue (FFPET). Previous reports of RNA extraction and amplification from FFPET are limited and do not enable global cDNA amplification. This study used polyA PCR to generate globally amplified cDNA from RNA extracted from formalin-fixed paraffin-embedded samples. RNA was extracted from nine routinely processed archival FFPET samples (lymph node, nasopharynx, prostate, lung and bone marrow) using an Ambion Paraffin Block RNA Isolation Kit. Global cDNA was generated by polyA RT-PCR and used in GAPDH specific PCR and PCR for CD33, c-myb, and SNF2. PolyA cDNA was reamplified by polyA PCR and the reamplified cDNA also used in GAPDH PCR. RNA was extracted from all nine samples, but was degraded. PolyA RT-PCR generated cDNA from all samples and was positive for GAPDH PCR in seven. PCR for CD33, c-myb, and SNF2 was positive in all samples tested. Following reamplification, the polyA cDNA remained positive for GAPDH by PCR. The results demonstrate the feasibility of globally amplifying RNA isolated from archival FFPET samples using polyA RT-PCR, which generates a renewable cDNA pool that can be probed for any cDNA species and reamplified as necessary.     

Intraluminal Radiation for Esophageal Cancer: A Howard University Technique

The objective of radiotherapeutic management in esophageal cancer is to accomplish maximum tumor sterilization with minimal normal tissue damage. This sincere effort is most often countered by the differential in tumor dose response vs normal tissue tolerance. Intraluminal isotope radiation, with its inherent advantage of rapid dose falloff, spares the lungs, the spinal cord, and other vital structures, yet yields adequately high doses to esophageal tumor. Though in existence since the turn of the century, the method of intracavitary radium bougie application dropped out of favor due to technical difficulties imposed by the size of the radium source and radiation exposure to the personnel involved. The authors describe a simple “iridium 192 afterloading intraluminal technique” that eliminates technical problems and reduces radiation exposure considerably.     

Missed opportunities for the prevention of cardiovascular disease among British hypertensives in primary care.

BACKGROUND: High-risk strategies for the prevention of cardiovascular disease (CVD) among hypertensive patients require knowledge of the prevalence and interaction of modifiable risk factors to ensure effective targeting of interventions. Comparatively little is known of risk-factor profiles and their modification among hypertensives in primary care. AIM: The present study was designed to explore relationships between patients' knowledge of CVD risk factors, their perception of personal risk and health behaviours, and their use of lifestyle interventions. METHOD: A cross-sectional survey of 2676 men and women with mild to moderate hypertension (diastolic blood pressure 95-115 mmHg), and their general practitioners, recruited from 1044 general practices throughout the UK, was conducted. RESULTS: Levels of modifiable risk factors were high, although there was considerable variation by age and sex; most (98.5%) patients had at least one additional CVD risk factor. A lower standard of living was associated with a higher prevalence of 'unhealthy' behaviours. Out of those with a current lifestyle problem, 85% of obese patients, 59% of smokers, 47% of excess drinkers, 49% of those with dietary risk factors and 32% of inactive patients claimed to have adopted healthier behaviours within the past 3 months. Older subjects and those with a lower standard of living were less likely to acknowledge risks, and those who did were less likely to report improving their lifestyles. While 71% of patients recalled receiving lifestyle advice, the coverage and targeting of specific interventions was generally poor. Overall, 60% of the sample had received advice on weight control, 47% on diet, 38% on exercise, 38% on smoking and 36% on alcohol. Women and older people were less likely to be given relevant counseling, and there was no evidence of targeting with respect to subjects' social class, level of hypertension or duration of diagnosis. CONCLUSION: Lifestyle interventions are welcomed and are viewed as helpful by patients receiving them. Potential health gains among high-risk hypertensives are being lost because of poor targeting and coverage of those at greatest risk.