Michael S. Kipper

The ''hot'' patella

Increased patellar uptake on bone scans is seen quite commonly but the possible or probable etiologies of this finding have not been previously well described. A review of 100 consecutive bone scans showed that the incidence of bilateral “hot” patellae is 15%. Identified etiologies include osteoarthritic degenerative disease (35%), fracture, possible metastatic disease, bursitis, Pagets disease, and osteomyelitis. The value of careful history, physical examination, and radiographs is stressed.

Localization of a parathyroid adenoma by the addition of pinhole imaging to Tc-99m sestamibi dual-phase scintigraphy. Report of a case and review of experience

Scintigraphy using Tc-99m has been shown to be highly sensitive in localizing abnormal parathyroid glands in patients with hyperparathyroidism. False-negative studies most often are attributed to glandular size or location. The authors report a case of negative parathyroid imaging using standard dual-phase technique, which was converted to a positive study by the addition of a pinhole view. During a 1-year period, the authors systematically added an anterior-pinhole image of the neck to all equivocal or negative Tc-99m studies. Five of 19 patient studies were pinhole-image positive and standard-image negative or equivocal. In selected patients undergoing Tc-99m scintigraphy for hyperparathyroidism, the addition of a pinhole view may enhance study sensitivity and the confidence in interpretation.

Indium-111 white blood cell imaging.

Since the pioneer work of Thakur et al, in 1975, ln–111 labeled leukocyte imaging has evolved into a practical, highly accurate method for the identification of occult infection. Modifications of the labeling technique have improved efficiency as well as reduced labeling time. Virtually any nuclear medicine department can become proficient in cell labeling in a short time. A body of literature has grown in support of early claims of superiority over Ga–67 citrate. The white cell scan carries a sensitivity, specificity, and accuracy of greater than 90%. lndium–111 is well suited for external imaging (173 keV + 247 keV) and has a desirable half life of 67 hours. Images are significantly easier to interpret than gallium, testing is generally complete in 24 hours, and the cost is acceptable. The major advantage over gallium appears to be a greater specificity. Additionally there is lack of bowel excretion and no patient preparation is required. In addition to its proven efficacy in localizing occult abdominal and pelvic abscesses, preliminary reports are encouraging with respect to renal disease, inflammatory bowel disease, infected vs non-infected cysts, graft infections, and a host of other inflammatory conditions.

Increased submandibular gland uptake on thyroid scintigraphy due to Wharton's duct stone.

Multiple causes of extrathyroidal accumulation of radioiodine have been reported. The results of an 81-year-old womans scan showed unilateral submandibular concentration secondary to a stone obstructing Whartons duct. The scan had been ordered to assess thyromegaly. The serendipitous combination of scintiscan findings and clinical symptoms prompted further evaluation and surgical removal of the occlusive stone. A potential false-positive interpretation was avoided because of a careful patient history as well as physical examination of the submandibular regions. Salivary duct conclusion must be added to the list of causes of extra-thyroidal accumulation of radioiodine.

Gallbladder visualization at twenty-four hours with octreotide scintigraphy. Potential false-positive finding.

Somatostatin receptor scintigraphy with In-111 octreotide has shown excellent accuracy in many neuroendocrine tumors, including carcinoid. Substantial gallbladder activity may be present on early images; however, the administration of a fatty meal and/or the effect of time generally results in littl

False-positive Tl-201 SPECT Studies in Patients with Left Bundle Branch Block: Frequency and Clinical Significance

This study reports on the frequency and clinical significance of false-positive thallium studies in the interventricular septum in patients with left bundle branch block. In a 3-year period, 93 studies were performed on patients with complete left bundle branch block and sinus rhythm. Of these, 29 had a reversible septal defect; 17 are scored false-positive although only six had angiographic proof of normal left anterior descending coronary arteries. We conclude that thallium scintigraphy is indicated in patients with left bundle branch block, but caution is justified when reversible ischemia is demonstrated scintigraphically.

Calculation of relative glomerular filtration rate and correlation with delayed technetium-99m DMSA imaging.

The relative renal uptake of Tc-99m DMSA was compared with the relative glomerular filtration rate (GFR) in ten patients with serum creatinines ranging from 0.3 to 2.5 mg/dl. Relative GFR was based on the renal uptake of Tc-99m DTPA determined by two methods: 1) Integrating the counts from 1 to 3 minutes postinjection and correcting for background. 2) Totalizing the individual renal counts in a single 15-second frame from 2:45 minutes to 3:00 minutes postinjection and correcting for background. The two methods of determining relative DTPA uptake showed excellent correlation, r = 0.98. Relative DMSA uptake determined at 24 hours post-injection using computer-assisted regions of interest showed excellent correlation with the relative GFR determined by either the integral or single-frame method, r = 0.98. The addition of background subtraction for the DMSA images at 24 hours did not improve the correlation.

The potential role of /sup 111/In white blood cell scans in patients with inflammatory bowel disease

In many institutions, the use of In-111 white blood cell (WBC) scans have become routine for abscess detection. Its use for the detection of bone and joint inflammation, renal disease, and myocardial infarction has also been reported. Two patients are presented whose In-111 studies were of major clinical value in the management of their inflammatory bowel disease. In one, the diagnosis was suggested, and in the second, the extent of disease was defined. The potential role of In-111 WBC imaging in inflammatory bowel disease--for diagnosis, staging, and monitoring response to therapy--are discussed. Possible pitfalls as well as a comprehensive prospective study are suggested.

The 24-hour Tl-201 image in dual isotope myocardial perfusion scintigraphy : Clinical utility and prognostic significance

This study assessed the effect on clinical decision making and the possible prognostic significance of the 24-hour Tl-201 image in patients undergoing Tl-201-MIBI dual-isotope myocardial scintigraphy. The records of all patients who underwent 24-hour Tl-201 imaging as part of their myocardial perfusion study from 1994 to 1996 were reviewed. Follow-up evaluations were obtained from the referring physician or by direct patient contact. Fifty-six patients underwent a total of 57 studies; four patients were lost to follow-up. Of the 53 studies evaluated, 29 showed no change between the standard rest images and the 24-hour images; these patients were reported to have myocardial scar. Of these 29 patients, 25 were treated medically without further evaluation; 24 of these 25 patients remained stable. Four of the 29 patients had further evaluation; 2 patients had coronary artery bypass graft, 1 had a stent placed, and 1 remained stable. Twenty-four patients showed definite improvement or normalization of their study results by 24 hours; they were reported as ischemic. Of these 24 patients, 11 were treated medically without further evaluation; 9 remained stable, whereas 2 had adverse events. The remaining 13 patients required further evaluation; 4 remained stable, whereas 9 had adverse events (4 = increasing angina; 1 = stent; 1 = rotoblator; 2 = percutaneous transluminal coronary angioplasty; 1 = death). Twenty-four-hour imaging contributes to clinical decision making and may identify a subset of patients at risk for subsequent complications.

I-131 MIBG detection of metastatic hepatic carcinoid

A 59-year-old man was referred for MIBG imaging because he had been diagnosed with carcinoid syndrome. Five HIAA levels were markedly elevated, and he had classic symptoms of flushing and diarrhea. An I-131 MIBG study was performed in conjunction with Tc-99m sulfur colloid liver imaging, and it demonstrated multiple focal areas of pathologic accumulation of MIBG in areas that were cold on the liver scan. This patient is now under evaluation for I-131 MIBG therapy. Demonstrable uptake on the patients diagnostic MIBG scan suggested the potential for MIBG therapy. Although the sensitivity of MIBG in the detection of carcinoid is suboptimal, it is of value in selected patients, including those under consideration for the administration of high-dose MIBG (i.e., 200-250 mCi) as treatment when other options have been unsuccessful