Chan H. Park

Abnormal thallium-201 scans in patients with chest pain and angiographically normal coronary arteries

We reviewed the exercise thallium-201 (TI-201) scans and clinical data of 41 patients with chest pain and normal coronary arteries to identify clinical factors associated with false-positive studies. Exercise TI-201 studies were performed before angiography and often precipitated referral. Sex, beta-blocker therapy, anginal pattern, and results of exercise electrocardiography were evaluated and compared with TI-201 imaging. A negative TI-201 study was the most common finding (p less than 0.005). Of the 41 patients, 11 (27%) had abnormal exercise TI-201 scans. No clinical factor was significantly associated with a false-positive TI-201 scans. Of the 11 patients with abnormal scans, 9 had greater than or equal to 1 cardiac abnormality: right bundle branch block in 2, mitral valve prolapse in 3, paroxysmal atrial fibrillation in 2, abnormal left ventricular diastolic pressure in 3, and left bundle branch block in 1. Thus, (1) when results of exercise TI-201 imaging are used to refer patients for angiography, false-positive TI-201 studies are common; (2) sex, beta blockade, anginal pattern, and results of exercise electrocardiogram are not useful predictors of a false-positive TI-201 study; and (3) patients with chest pain, normal coronary arteries, and abnormal TI-201 scans frequently have other cardiac abnormalities.

Usefulness of ST-segment depression as a sign of coronary artery disease when confined to the postexercise recovery period

Abstract Although ST-segment depression during exercise is a diagnostic sign usually indicating the presence of coronary artery disease (CAD), the significance of ST-segment change confined only to the postexercise recovery period remains unknown. We evaluated 2,000 exercise electrocardiographic (ECG) tests and identified 62 patients who developed ≥1 mm horizontal or downsloping ST depression in the postexercise period despite a negative ST response during exercise (Figure 1). Isolated postexercise ST-segment depression was assessed as a sign of CAD by thallium-201 perfusion imaging and, in a subgroup of 26 patients, by coronary angiography.

Cavo-portal shunting in superior and inferior vena caval obstruction.

Focal radionuclide accumulation of Tc-99m sulfur colloid (SC) and Tc-99m macroaggregated albumin (MAA) in the liver has been reported in both inferior and superior vena caval obstruction. We studied a patient with uniform radionuclide accumulation of Tc-99m MAA in the liver during lung scintigraphy. In this patient, both the superior vena cava (SVC) and the inferior vena cava (IVC) were obstructed. Most of the systemic venous return appeared to be passing through the liver on its way to the heart, through the anastomoses between the systemic veins and the portal vein. To the best of our knowledge, uniform hepatic uptake in vena caval obstruction is not reported in the literature.

Effect of reserpine on salivary gland radioiodine uptake in thyroid cancer

Nine patients with thyroid cancer were treated with reserpine in an attempt to reduce radiation exposure to the salivary glands from 100-150 mCi doses of I-131 therapy to thyroid remnants or metastases. Three control patients were not treated with reserpine but did receive 100-150 mCi of I-131. Parotid/background ratios of activity after radioabiative doses of I-131 in patients not treated with reserpine were significantly higher than the patients treated with reserpine, and this was also true seven days after the radioabiative dose. Combined therapy with reserpine, chewing gum, lemon candies, and hydration is suggested for the prevention of sialadenitis and xerostomia due to large doses of radioiodine.

Streaming in portal vein. Its effect on the spread of metastases to the liver.

Fifty-five consecutive patients with colorectal carcinoma and hepatic metastases on the Tc-99m sulfur colloid liver/spleen scan (TSC) were evaluated to see if the pattern of spread of colorectal metastases was affected by the venous drainage of the primary site. The results suggest that significant streaming probably exists in the portal vein and the spread of metastases to the liver is affected by it. This information has a potential clinical implication in terms of diagnostic workup and chemotherapeutic infusions. It also supports the speculation that a streaming effect exists in humans.

The use of scintigraphic studies in mid-ventricular obstructive cardiomyopathy to rule out pseudoaneurysm.

A pseudo-pseudo aneurysm of the left ventricle due to mid-ventricular obstruction from asymmetric septal hypertrophy is presented. A case of mid-ventricular hypertrophic obstructive cardiomyopathy (MVHOCM) was evaluated by means of echocardiography, angiocardiography, gated cardiac blood pool scanning, and a TI-201 myocardial scan. The gated cardiac blood pool scan appearance of MVHOCM is similar to pseudoaneurysm of the left ventricle. TI-201 myocardial imaging, however, was able to distinguish between MVHOCM and pseudoaneurysm of the left ventricle.

Renal allograft rejection. Unusual scintigraphic findings

During sequential renal imaging for evaluation of clinically suspected rejection, focal areas of functioning renal tissue were seen in two cases of renal transplant in the midst of severe and irreversible renal allograft rejection. A probable explanation for this histopathologically confirmed and previously unreported finding is discussed.

Iofetamine HCl I-123 (Iodoamphetamine) brain SPECT atlas.

SPECT brain imaging using Iofetamine HC1 I-123 (IMP) has a great potential in the evaluation of various neurologic disorders. Transverse, coronal, and sagittal sectional IMP images obtained using a single head rotating gamma camera system are correlated with corresponding normal brain slices in this atlas.

Technetium-99m pyrophosphate scintigraphy for the detection of acute myocardial infarction. How useful is it?

To evaluate the contribution of Tc-99m pyrophosphate scintigraphy (TPS) on the overall management of patients suspected of having acute myocardial infarction (AMI), hospital records of 58 consecutive patients who underwent TPS, were evaluated in depth. The results indicate that TPS was essential for the diagnosis of AMI in 16% of the patients. TPS was most rewarding in perioperative patients and in patients with borderline or uninterpretable electrocardiographs and enzyme changes. Also, in some cases, TPS was able to confirm or exclude the diagnosis of AMI prior to the confirmation by serial electrocardiograms (ECG) and serial enzyme changes. TPS was less rewarding in patients with clinically low index of suspicion for AMI. It may also be confusing in patients with high clinical likelihood of AMI and a history of prior myocardial infarction because of the possibility of persistently positive TPS in some of these patients. Considering the limitations of ECGs, the cardiac enzymes, and atypical clinical presentations in the patient population we evaluated, TPS appears to be fairly accurate when the scintigraphic findings are compared with the final diagnosis at the time of discharge from the hospital.