I-123 MIBG cardiac scintigraphy and autonomic test evaluation in multiple sclerosis patients.

Autonomic symptoms are common in multiple sclerosis (MS) patients and may cause significant disability. The purpose of this study was to evaluate direct cardiac sympathetic denervation in MS patients with I-123 MIBG cardiac scintigraphy compared with other parasympathetic electrophysiological examinations of autonomic dysfunction. Ten patients with MS and 7 age- and sex-matched control subjects were prospectively evaluated. The neurological deficit and disability stages of the patients were rated according to the Kurtzke Expanded Disability Status Scale (EDSS). Autonomic tests included the R-R interval, Valsalva ratio and standup test. All patients and control subjects had planar and SPECT cardiac scintigraphy with I-123 MIBG injection. Seven MS patients had relapsing-remitting (R-R) type and three had secondary progressive type (SP). A pathological MIBG cardiac washout rate was found in 3/10 MS patients, all of them with SP-MS. The other seven had normal washout rates. No correlation was found between the scan and the individual parasympathetic autonomic test results. I-123 MIBG myocardial scintigraphy may detect direct disturbances of the sympathetic cardiac function in patients with MS in addition to parasympathetic dysfunction tests and can be an important additional means of assessing autonomic pathways. Determination in MS of the co-existence of autonomic dysfunction, especially the cardiac sympathetic involvement in the SP type, may aid in evaluation of disease severity and cardiac function follow-up.

The hot skull sign on bone scans of obese patients resulting from disparate soft tissue attenuation.

We have frequently observed diffusely increased skull activity on bone scans of obese patients, who do not have evidence of metabolic or metastatic bone disease. Skull activity of 25 obese patients were compared to that of age and sex-matched nonobese 25 patients visually and quantitatively. The results clearly indicated that diffusely increased skull activity is significantly more common on bone scans of obese patients because of disparate attenuation of overlying soft tissues. This knowledge will help obviate the need for additional radiologic and/or laboratory tests in search of other conditions associated with hot skull, ie, Paget's disease and metabolic bone disorders such as renal osteodystrophy and primary hyperparathyroidism.

Incremental diagnostic value of preoperative 99mTc-MIBI SPECT in patients with a parathyroid adenoma.

UNLABELLED: The purpose of this prospective study was to evaluate the diagnostic value of early parathyroid SPECT combined with quantitative analysis as compared with planar imaging in patients undergoing minimally invasive radioguided surgery. METHODS: A total of 52 consecutive patients with primary hyperparathyroidism underwent planar and SPECT parathyroid scintigraphy 2-5 d before surgery. Each patient had a single-tracer dual-phase technique using (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) and a double-tracer subtraction technique using a delayed (99m)Tc-pertechnetate scan. Immediately after the first (99m)Tc-MIBI planar image, a SPECT study was acquired. Before radioguided parathyroidectomy, each patient was reinjected with (99m)Tc-MIBI. Serum calcium levels were available for all patents before surgery and at 8 and 24 h after surgery. Serum parathyroid hormone (PTH) levels were also available for all patients. Quantitative analysis was performed using the average count ratio of parathyroid to left thyroid lobe, right thyroid lobe, and maximum thyroid activity. All patients had histopathologic examination of the removed glands. RESULTS: The average time for radioguided surgery was 30 min (range, 20-40 min). Postsurgical calcium levels correlated significantly with the adenoma weight (r = 0.5; P = 0.016). Combined planar scintigraphy correctly identified 41 adenomas (79%). SPECT increased the sensitivity to 96%. SPECT was superior to planar imaging in 9 patients, mainly in patients with ectopic adenomas or with multinodular goiters. Gland size did not affect significantly the detectability of SPECT. (99m)Tc-MIBI retention was noted in only 31 adenomas (60%). The average uptake ratios of parathyroid counts to the left lobe, right lobe, and maximum thyroid activity were 1.20 +/- 0.42, 1.29 +/- 0.45, and 0.84 +/- 0.35, respectively. The latter ratio was significantly correlated with PTH levels before surgery (r = 0.408; P = 0.04). CONCLUSION: Our data indicate that early preoperative SPECT in patients with primary hyperparathyroidism is essential for accurate localization of parathyroid adenomas and for the selection of patients who are candidates for minimally invasive radioguided surgery. Planar parathyroid imaging is less sensitive compared with SPECT, and washout kinetics of (99m)Tc-MIBI are unreliable in the dual-phase technique. Patients with higher presurgical PTH levels may especially benefit from radioguided surgery.