Detecting unsuspected thyroid dysfunction by the free thyroxine index.

The free thyroxine index (FTI) was used in 2,704 adults to detect unsuspected thyroid dysfunction. Among 2,581 adults found to be clinically euthyroid without thyroid medication, 2,571 had a truly normal FTI (121 to 360) and ten had a falsely abnormal FTI (seven less than 121, three greater than 360). Among 25 subjects with newly diagnosed thyroid dysfunction, there were eight hyperthyroid (prevalence, 0.31%) and 14 hypothyroid (prevalence, 0.50%) subjects. The sensitivity of the FTI was 1.0, and the specificity was 0.996. The predictive value of an abnormal FTI with a prevalence of 0.81% was 67%. The cost to find a new case averaged $127. The annual incidence of symptomatic hyperthyroidism was 0.05%; of hypothyroidism, about 0.08%. We conclude that the FTI is cost-effective for case finding in thyroid dysfunction.

Radioimmunoassay for herpes simplex virus.

Radioimmunoassay has been used for time in the detection of the Australia Antigen. In this experiment, radioimmunoassay with Iodine-125 (125I) permitted rapid detection of the presence of herpes simplex virus, type I, in vitro. This is a convenient technique for the detection of virus, which now requires laborious methods involving observation for the cytopathic effect of virus upon cultured cells.

A new 80-lens oscilloscope camera for routine dynamic organ scintigraphy.

A simple, reliable, and cost-effective 80-lens photographic camera records dynamically from the oscilloscope of a scintillation camera without degradation of spatial resolution or data loss. Most physiologic events can be recorded completely and without interruption on a single 9 X 12-cm negative film as 40 sequential time-frames, using one of six available exposures per frame. In addition, 40 simultaneous sequential time-frames of four times the chosen duration may bracket a transient event with increased data density. The 80-lens camera has been used routinely for perfusion scintigraphy of brain, heart, liver, kidneys,and lungs with excellent results.

Diagnosis of acute cholecystitis using hepatobiliary scan with technetium-99m PIPIDA.

Sixty patients were evaluated for acute abdominal pain using technetium-99m PIPIDA hepatobiliary imaging. The sensitivity of the test was 90.6 percent in all patients and the accuracy was 93.3 percent. In the evaluation of acutely ill patients with right upper quadrant pain, fever, nausea and vomiting, hepatobiliary imaging with PIPIDA is the preferred test for diagnosing acute cholecystitis. If the test is positive, disease of the gallbladder and probably acute cholecystitis are present. Early operation can proceed if desirable. If the test is negative and the bilirubin level is less than 5.0 mg/dl, acute cholecystitis is not present. In such cases conservative treatment is appropriate, and follow-up tests should be performed to evaluate the possibility of chronic cholecystitis. When the bilirubin level exceeds 5.0 mg/dl, the test is often indeterminate.

The importance of perfusion imaging in brain scintigraphy for subdural hematoma.

The authors report a case of subdural hematoma in a patient who showed bilateral perfusion defects, highly characteristic of subdural hematoma, but did not show the expected complementary static abnormalities. This appears to be the first such case in the literature.

Heterogeneity of congenital primary hypothyroidism: the importance of thyroid scintigraphy.

Current newborn screening programs in California and most of the U.S. depend for diagnosis of congenital primary hypothyroidism on demonstrating an elevated thyrotropin (TSH) level in infants with the lowest 5% to 10% of thyroxine (T4) levels by filter-paper bloodspot test. The diagnosis of primary congenital hypothyroidism based on low T4 with high TSH fails to distinguish between transient hypothyroidism, ectopic or hypoplastic thyroid, athyrosis, dyshormonogenesis, and transient hyperthyrotropinemia. We screened 166,300 newborn infants for primary congenital hypothyroidism for 6.5 years and confirmed the diagnosis in 46 cases; none of these patients had a goiter. Thyroid scintigraphy was performed in 40 with technetium-99m (Tc-99m) in the first eight cases tested and iodine-123 (I-123) in 29 of the last 32 cases. Fifteen infants were athyroid and seven had ectopic or hypoplastic glands; in 18 the thyroid gland appeared normal (present, normal location). Congenital hypothyroidism represents a spectrum of diseases from transient underactivity to complete absence of the thyroid gland. We recommend that, before starting treatment, a specific anatomic and functional diagnosis be confirmed by thyroid scintigraphy and other thyroid function tests.

Dynamic/static brain scintigraphy: an effective screening test for subdural hematoma.

Dynamic perfusion scintigraphy of the brain was coupled with the delayed static scan in 5,853 studies as a screening test for neurological disease. Of approximately 1,000 patients referred for investigation for possible subdural hematoma (SDH), 23 proved to have SDH at surgery. Their scintigraphic abnormalities were analyzed and classified. When neither study indicates abnormality, angiography is not required, as SDH is unlikely. When the scintigraphic appearance is characteristic of SDH, angiography or surgical exploration is mandatory, since SDH is probably present. When the scintigraphic findings are consistent with but not typical of SDH, the study remains useful as a screening procedure, but the decision to proceed with angiography is based primarily on the neurological course.

Double-antibody radioimmunoassay of thyroid microsomal antibody in serum.

We describe a double-antibody radioimmunoassay for antimicrosomal antibodies in serum. Antigen in centrifuged pellets of microsome is solubilized by treatment with sodium deoxycholate solution and radiolabeled (125I] by the Chloramine T method. A 10-microL aliquot of human serum or antimicrosomal antibody standard is incubated overnight at room temperature with 125I-labeled microsome. Bound radiolabeled microsome is separated by precipitation with goat antihuman IgG antiserum. The percentage of 125I-labeled microsome bound by each serum is calculated, and its concentration of antimicrosomal antibody interpolated from a standard curve. The prevalence of abnormal antimicrosomal antibody was 16% in a self-referred asymptomatic or not acutely ill group of patients having a periodic multiphasic health examination. Values for patients with certain thyroid diseases generally agreed with other published data. We conclude that our assay is sensitive, precise, and accurate, and is more efficient for routine measurement of antimicrosomal antibody than the currently used solid-phase radioimmunoassay.

Indium-111 leukocyte imaging in appendicitis.

Indium-111-labeled leukocyte scintigraphy was applied to the diagnosis of acute appendicitis. Thirty-two patients observed in the hospital for possible appendicitis were prospectively studied. Scanning was done 2 hr after radiopharmaceutical injection. Thirteen scans were positive for acute appendicitis, and all but one were confirmed at laparotomy. In addition, two cases of colitis and two cases of peritonitis were detected. Of 15 negative studies, 11 had a benign course. Four patients with negative studies had laparotomy; two were found to have appendicitis and two had a normal appendix. Of 14 proven cases of appendicitis, 12 scans were positive for appendicitis with one false-positive scan, providing a sensitivity of 86%. Specificity was 93%: all negative cases except one had negative scans. Overall accuracy was 91% (29 of 32), comparing favorably with the accepted false-positive laparotomy rate of 25%. Use of In-111-labeled leukocyte scintigraphy serves to reduce the false-positive laparotomy rate and to shorten the clinical observation time in patients with acute appendicitis.