Radioiodine in the treatment of medullary carcinoma of the thyroid.

Medullary carcinoma (MC) of the thyroid, in contrast to papillary-follicular carcinoma, fails to concentrate iodine and thus has not been treated with radioactive iodine. We have successfully treated a 16-yr-old Mexican-American girl with residual MC after maximal thyroidectomy (Tx), utilizing radioiodine (131I) to deliver radiation to residual follicular cells in the tumor bed. Immediately after Tx, plasma thyrocalcitonin levels before and during calcium infusion were all elevated (640--1200 pg/ml). 131I (150 mCi) was administered 12 days after Tx after four daily im injections of bovine TSH. Three months after 131I therapy, thyrocalcitonin levels before and during calcium infusion were all normal (less than 50 pg/ml). Ten months after 131I therapy, thyrocalcitonin levels before and after iv pentagastrin were all normal (less than 60 pg/ml). These results suggest that parafollicular cells are radiosensitive, and that therapeutic levels of radiation can be delivered to these cells after Tx if iodine trapping by the remaining follicular cells is enhanced by high levels of circulating TSH. 131I may be the therapy of choice for MC after Tx, if disease has not spread beyond the area proximate to the thyroid gland.

"EAR" artifact in brain scans.

The ear closest to the camera may be imaged in high-resolution lateral views of the brain as a structure anterior to the lateral sinus. The artifact can usually be eliminated by taping the auricle down. Artifacts such as this can be expected to become somewhat more of a problem as image resolution improves.

Adenocarcinoma of the lung with marked uptake of 99mTc-pertechnetate: case report.

Following biopsy of a hilar mass, a heart scan performed with 99mTc-pertechnetate showed intense uptake in the mass. The degree of radionuclide concentration suggested that the mass was glandular tissue, most likely an adenoma or adenocarcinoma. Biopsy revealed a mucinsecreting adenocarcinoma. Review of the literature showed examples of active glandular concentration of pertechnetate in the thyroid, gastric mucosa, breast, lacrimal glands, and colon. This case provides an example of reasoning by which the scan interpretation came closer to the actual tissue diagnosis than is usually possible.

Cerebral perfusion deficit masked by Paget's disease of skull.

Prominent extracerebral perfusion on an emission angiogram of the head in a patient with Paget's disease of the skull masked an underlying intracerebral perfusion deficiency, due to occlusion of the left middle cerebral artery.

Detection of bronchopleural-subarachnoid fistula by radionuclide myelography: case report.

Radionuclide myeloscintigraphy has previously been used to demonstrate subarachnoid fistulae. In the present case a patient with bronchogenic carcinoma developed spontaneous pneumocephalus postoperatively. Chest radiographs showed an air-fluid level in the postoperative area. Various diagnostic tests were used, but only a radionuclide myeloscintigram showed the presence of a bronchopleural-subarachnoid fistula.

Glucose transport and utilization in the human brain: model using carbon-11 methylglucose and positron emission tomography.

3-0-[11C]-Methyl-D-glucose (CMG) is specifically suited for measuring carrier facilitated glucose (G) transport; it enters the free G pool in tissue from where it is not utilized for metabolism in contrast to G, but is transported back into circulation. The ratio of carrier affinity for G and CMG was reported to be 1.11. By simultaneously measuring CMG concentration in plasma and in cerebral cortex in vivo with positron tomography at 1-min intervals for 40 min, two time-activity curves are obtained, as reported previously, which together with the G concentration in plasma yield the in vivo rate constants of G transport across the blood-brain barrier and the rate of G inflow; a repeat measurement at a different G concentration in plasma gives the in vivo Michaelis-Menten constant KM and the maximal rate of transport VMAX. The present paper summarizes and extends this approach to analyzing the free G pool in tissue, the rate of G return to circulation, and the rate of G exit into metabolism with its corresponding rate constants. The data from six volunteers agreed with results reported for the individual biochemical parameters in primate brains.

Differentiation between malignant and benign solitary thyroid nodules by fluorescent scanning.

A quantitative fluorescent technique has been developed for making in vivo iodine content determinations of the total thyroid gland or of selected parts. In solitary thyroid nodules "cold" to radionuclide studies, the ratio of iodine content in the nodule to that in a corresponding area of the contralateral lobe has proven to be a good indicator of malignancy. In a preliminary study of 42 surgical patients, an iodine content ratio (ICR) below 0.60 (chosen a posteriori) proved to be an excellent indication of malignancy with a sensitivity of 100%, a specificity (predictive value) of 79%, and an overall accuracy of 90%. Further definitive studies are needed to verify these preliminary observations.

A full-field modular gamma camera.

A modular gamma ray camera is described that gives useful image information over its entire crystal face. The lack of dead area on the periphery of the camera is made possible by a unique application of digital electronics and optimal position estimation using maximum likelihood (ML) estimates. The ML estimates are calculated directly from photomultiplier tube responses and stored in a lookup table, so the restriction of calculating the position estimates in separate circuitry is removed. Each module is designed to be optically and electronically independent, so that many modules can be combined in a large system. Results from a prototypical module, which has an active crystal area of 10 cm X 10 cm, are presented.

A stationary hemispherical SPECT imager for three-dimensional brain imaging.

A completely stationary, hemispherical-coded aperture SPECT imaging system was designed to produce three-dimensional images of the brain. The system consisted of a hemispherical multiple-pinhole coded aperture and 20 small (100 x 100 mm crystal area) digital gamma cameras. Reconstructions and measured performance specifications from two laboratory versions of the imager are presented. The reconstructed field of view of these systems was an ellipsoidal region with semi-diameters of 100 x 100 x 50 mm. The reconstructed spatial resolution for a point source in air at the center of this field was found to be 4.8 mm FWHM and the corresponding system sensitivity was 36 cps/microCi. An analysis using an ideal-observer model indicated that the multiplexed projection data suffered a 21% degradation relative to similar, but nonmultiplexed SPECT data. Therefore, by this measure, the effective sensitivity of the brain imager was 79% of the measured value.

Hemodynamic comparison of ventricular pacing, atrioventricular sequential pacing, and atrial synchronous ventricular pacing using radionuclide ventriculography.

To assess the hemodynamic effects of physiologic pacing, 13 patients with DDD pacemakers who had varying degrees of atrioventricular (AV) block were studied with radionuclide ventriculography during VVI, DVI and VDD modes. Radionuclide ventriculography was performed with patient in the supine position at rest 5 to 10 minutes after the pacing mode and AV delay were changed. The AV delays selected were short (mean 147 +/- 4.8 ms) and long (mean 197 +/- 4.8 ms), with a constant difference of 50 ms. During VVI, 6 patients (group 1) had a left ventricular ejection fraction of 40% or less (mean 22 +/- 11) and 7 patients (group 2) had an ejection fraction of more than 40% (mean 59 +/- 11). Comparisons of ejection fraction, end-diastolic volume and cardiac index between VVI and both modes of AV pacing (VDD and DVI) and between long and short AV delays led to the following conclusions: DVI or VDD pacing produces more beneficial hemodynamic effects than VVI, and these effects are more pronounced in patients with low ejection fraction if longer AV delay is used. The VDD mode significantly improves ventricular function over the DVI mode in patients with an ejection fraction of more than 40% independent of heart rate. Longer AV delay is essential in patients with an ejection fraction of 40% or less to improve ventricular function with physiologic pacing.

Introduction to clinical decision making.

In the last few years there has been a remarkable increase in the amount of clinical data in the average hospital chart, and more and more problem-solving algorithms have been developed. We need better "thinking tools" to help us handle the flow of information. The term "clinical decision making" is used to describe a systematic way to handle data and algorithms to decide on a best course of action. This introductory article discusses some of the problems in establishing a decision criterion, both for a population and for an individual patient. Comparing the probabilities and utilities of various diagnostic outcomes (true positive, false positive, etc.) leads to a diagnostic strategy. The article also discusses conditional probability. Bayes' theorem, and likelihood ratios.

Cost-effectiveness in nuclear medicine.

There are many pressures on nuclear medicine physicians to keep costs down and to produce the most efficacious results for the money spent. A procedure is cost-effective if its benefits (correct diagnosis, effective treatment, etc.) are worth the additional costs (money, radiation dose, etc.). The benefits of diagnostic procedures are measured by test performance (diagnostic efficacy [efficacy-D]), which in turn depends on a specific task: detection, classification, localization, or quantitation. For the detection task, measures of test performance include sensitivity, specificity, predictive value, accuracy, diagnostic utility, posttest versus pretest disease probability, area under a receiver operating characteristic (ROC) curve, and others. Standard measures of test performance in the classification, localization, and quantitation tasks have not yet been developed. Efficacy-M (management efficacy) is a measure of the extent to which a procedure influences patient management appropriately. Efficacy-O (outcome efficacy) is a measure of the success of therapeutic procedures. Some publications illustrating these points are presented. Costs associated with nuclear medicine procedures include money, time, discomfort, possible drug reactions, radiation dose, and the hypothetical risk of radiation-associated cancer. The public's perception of these latter risks, or costs, is much higher than our knowledge would justify. Decision trees are useful for laying out all possible strategies, outcomes, costs, and benefits, and estimating the cost-effectiveness of each strategy. Some articles estimating cost-effectiveness in nuclear medicine are reviewed, although few articles in the literature make any detailed use of decision analysis. Much work remains to be done in forming a coherent, consistent procedure for assessing cost-effectiveness in nuclear medicine.

A utility-based model for comparing the cost-effectiveness of diagnostic studies.

The effective cost of a diagnostic test is the money spent per unit of diagnostic performance. The latter can be measured as diagnostic utility (DU), the probability-weighted sum of the utilities of the four test outcomes TP, TN, FP, and FN: DU = U(TP)P(TP) + U(TN)P(TN) + U(FP)P(FP) + U(FN)P(FN). DU (which also is called expected utility) incorporates the clinical decision analytic variables sensitivity (Se), specificity (Sp), equivocal fraction (EF), disease probability (P(D)), and outcome utility (U). DU is not an inherent property of a diagnostic test but of test-observer interactions in a clinical setting. The model sets the effective cost (EC) of a diagnostic test = actual direct cost (ADC)/DU. When DU = 1 (perfect test) EC = ADC and the patient benefits from the test dollar for dollar. When DU less than 1, EC exceeds ADC. If DU approaches O, EC becomes infinite; the test has no effectiveness at any cost. DU depends strongly on P(D) if Se and Sp differ significantly; then EC also depends on P(D), and the effective cost of a test performed in the wrong P(D) setting may be several times its actual direct cost. This model of comparing effective costs compares actual direct cost with clinical measures of test performance and utility values that allow expression of patient/doctor fears and preferences. It offers a more clinically realistic setting than models based on costs alone.

Mechanisms of satiety and gastric emptying after gastric partitioning and bypass.

The patterns of fundic and antral motility as well as changes in fundic pressure in response to balloon distention were evaluated in 26 patients before and after gastric partitioning (18 patients) or gastric bypass (8 patients). In addition, the rate of gastric emptying, as measured by the ingestion of 99mTc-tagged chicken liver, was determined after gastric partitioning (12 patients) and bypass (7 patients). A striking alteration in the motility of the fundus occurs after both gastric partitioning and bypass. Normal pressure waves of the fundus disappear with both procedures. Fullness after both operations is secondary to distension of the pouch rather than to an increase in pressure. Changes in antral motility, inhibition, and recovery seem to be neurally mediated. The gastric emptying rate was 6.9% +/0 2.9% per minute after gastric bypass and 1.8% +/- 0.4% per minute after partitioning. Delayed emptying could be an additional benefit of gastric partitioning.

Radionuclide bone scanning in diseases of the spine.

Radionuclide bone scans provide a sensitive, no-risk diagnostic technique for the detection and evaluation of a wide variety of diseases of the spine. Scans and radiographs provide complementary diagnostic information, and should both be considered in the medical imaging portion of the diagnostic plan.

Long-term surface cortical cerebral blood flow monitoring in temporal lobe epilepsy.

Long-term subdural surface cortical cerebral blood flow (CBF) and electrocorticographic monitoring was performed in 12 patients with complex partial seizures. A total of 40 seizures were analyzed. Baseline CBF values from nonepileptic and epileptic temporal lobe (mean +/- standard error) were 60.0 +/- 1.0 and 50.2 +/- 1.8 ml/100 g per minute, respectively (P < 0.05). In general, clinical seizure onset was preceded by a 20-minute preictal CBF increase from baseline in the epileptic temporal lobe. Peak early postictal CBF values of nonepileptic and epileptic temporal lobes were 57.7 +/- 13.3 and 89.0 +/- 21.7 ml/100 g per minute (P > 0.05) at 5.2 +/- 2.2 and 2.4 +/- 1.0 minutes (P > 0.05) after clinical seizure onset, respectively. Statistically significant differences between nonepileptic and epileptic temporal lobe CBF were detected at 50 minutes (74.0 +/- 14.2 and 37.5 +/- 9.2 ml/100 g per minute, respectively; P < 0.05) and 60 minutes (75.6 +/- 13.6 and 36.1 +/- 8.5 ml/100 g per minute, respectively; P < 0.05) postictal. The data suggest that the optimal times for CBF analysis to differentiate epileptic from nonepileptic temporal lobe are 1) during the interictal period and 2) late (50 to 60 minutes) postictal. The results of this study should improve the understanding of the dynamic cerebral perfusion patterns in the epileptic human brain.

Bone scans of the facial bones: normal anatomy.

Some features of facial anatomy have been identified on 99mTc polyphosphate bone scans by a comparison of scans, radiographs, and photographs. 99mTc polyphosphate bone scans are used clinically to show bone injury and increased osteoblastic activity; the primary use is to identify malignancy and other diseases involving bone. A knowledge of normal anatomy is of the utmost importance in the accurate interpretation of bone scans of the face.

Preoperative detection of sporadic parathyroid adenomas using technetium-99m-sestamibi: what role in clinical practice?

Preoperative localization of pathologic parathyroid glands remains controversial. Because experienced parathyroid surgeons can identify and cure parathyroid pathology in sporadic primary hyperparathyroidism in better than 95 per cent of first-time explorations, few consider preoperative localization studies cost effective in this population. However, the primary reason for failure at the initial exploration is the inability of the surgeon to identify an adenoma in a normal anatomical location. Recent reports have indicated that operative time can be reduced and initial success improved with preoperative localization of adenomas using the highly sensitive technetium-99m (Tc)-sestamibi scan. We evaluated 16 consecutive patients with sporadic primary hyperparathyroidism using a double-phase Tc-sestamibi scan with delayed images, hypothesizing that 90 per cent of adenomas would be accurately detected, and furthermore that a negative scan would predict multigland disease. Of the 16 scans, 13 showed a focal delayed washout of the tracer, constituting a positive scan. Eleven of 13 were true positive (85%), with two false positive scans (15%), both of which also had nodular thyroid disease. The three negative scans were indeed hyperplastic multigland disease, determined at exploration. The mean operative time for a bilateral exploration for the true positive cases was 109 minutes, compared to 148 minutes for a small cohort group without imaging (not significant). In conclusion, 85 per cent of adenomas can be successfully localized with the Tc-sestamibi delayed-image technique, and may decrease operative time. Additionally, a negative scan is a likely predictor of multigland disease, which allows for improved preoperative patient education and preparation for cryopreservation. These data suggest that preoperative Tc-sestamibi scanning may improve the success rate for the occasional parathyroid surgeon, and that an extended prospective trial is warranted.

Patient perceptions of the need for chaperones during pelvic exams.

This report describes the attitudes of women patients about the presence and role of a chaperone during pelvic exams and factors associated with these perceptions. A questionnaire was mailed to a systematic sample of all adult women patients of an academic-affiliated family practice (n = 939) in a rural southeastern United States community. Approximately 64% of the sample responded, and 440 (91%) of the returned questionnaires could be used in the analysis. Over half of the patients had no gender preference for the examining physician; when a preference was indicated, it was for a woman physician. Patients expressing a preference were more likely to be younger, never married, nulliparous, and black. Gender of the examining physician was a major factor in the desire for a chaperone during pelvic exams. A chaperone was desired most often when the examining physician was male, and this was especially so when a female physician was preferred. The results indicate most women desired a chaperone when the physician was male, but preferred no chaperone or had no preference when a woman physician was involved.

Physical therapy education in family practice residency programs.

BACKGROUND: This study investigated the role and extent of physical therapy education in family practice residency programs. Physical therapy is not specifically included in graduate curricula guidelines, and the literature contains little information on its involvement in programs. METHODS: A questionnaire was developed to determine how physical therapy education is taught in family practice residencies. The questionnaire was mailed to all (391) directors of US-accredited family practice residency programs. RESULTS: A total of 256 directors (65.5%) responded. The majority of directors (67%) stated that there was a significant need for the physical therapy component. Only 52% (133/256), however, included physical therapy in their curricula. Physical therapy education was most frequently (67.6%, 92/136) included in required rotations (eg, orthopedics) and taught mostly by hospital-based physical therapists (77.0%, 104/135) or subspecialists (55.6%, 75/135). CONCLUSION: This study shows that physical therapy education offers a potentially relevant and important element of family practice residency training, but it has been underemphasized.