The role of labelled red blood cell scintigraphy in the detention of acute gastrointestinal bleeding

This paper describes the experience with 99m Technetium labelled red blood cell (99mTc RBC) scintigraphy in twenty-two patients presenting with acute gastrointestinal (GI) tract bleeding. Studies were postitive in thirteen cases - eight from the lower GI tract and five from the upper. The data from surgical intervention were available in ten cases. Scintigraphy cannot diagnose the cause of GI bleeding, as it is a nonspecific study. Its usefulness lies in its ability to accurately diagnose the bleeding site, as was shown in this study where there was good surgical correlation. The simplicity, reproducibility and reliability of the technique, particularly when bleeding rates are low and intermittent, make it, in our view, the first line of investigation in any patient with suspected bleeding from the colon or upper GI tract if endoscopic evaluation is not possible in the latter. Its current under-utilisation in the Caribbean may be a reflection of the lack of nuclear imaging facilities.(Au)

Implications of abnormal myocardial perfusion and normal angiography in patints with associated risk factors for coronary disease

Comparison between coronary angiography (CA) and SPECT myocardial perfusion scintigraphy (MPS) using Tc-99m labeled compounds in 30 patients (23 males, 7 females) yielded a sensitivity of 97 percent and a specificity of 76 percent for lesion detectability (p<0.01) using CA as the reference standard. Angiographic analysis initially ascribed the scintigraphic defects in 8 patients (5 males, 3 females) as falsely positive. Eleven coronary artery territories were involved: eight within the LAD and three within the RCA. Patient symptomatology however, prompted angiographic review which revealed myocardial bridging of the LAD in one male patient and differential perfusion of the LAD in two male patients. A review of the patients' history revealed associated risk factors such as diabetes, hyperlipidaemia, hypertension and smoking. Based on these findings, critical re-evaluation of other pathophysiolocial abnormalities in the absence of vascular stenosis should thus be sought in patients with positives MPD and associated risk factors to avoid unsuspected patient morbidity (AU)

Coronary angiography and myocardial perfusion scintigraphy: a correlative analysis - abstract

The assessment of myocardial perfusion has for many years been performed with thallous chloride (T1-201). This imaging agent suffers, however, from a number of well-recognized limitations, which has prompted a global search for better radiopharmaceuticals. Within the last two years, Technetium labelled myocardial perfusion imaging agents, namely, Sestamibi (Du Pont Pharma) and Tetrofosmin (Amersham) became available, and prompted us to evaluate the efficacy with respect to coronary angiography (CA) recently introduced at our institution. The data for both imaging agents were analyzed in fifty consecutive patients (ages 30 to 70 years), referred over the past eighteen months for myocardial perfusion scintigraphy (MPS). Twenty-five patients had combined MPS and CA studies. Comparative analysis for individual coronary artery territories yielded a sensitivity of 97 percent, specificity of 80 percent and an overall accuracy of 80 percent for MPS. Angiographic review of initially ascribed false positive MPS in eight patients revealed pathophysiological abnormalities other than coronary artery stenosis which accounted for the observed perfusion deficits. These included differential blood flow in two patients and myocardial bridging in one. The remaining false positives were attributed to diaphragmatic or breast attenuation (AU)

The metabolism of iron-dextran given as a total-dose infusion to iron deficient Jamaican subjects

The movements of iron-dextran, following a total dose infusion of up to 2550 mg. iron in six severely iron deficient patients, have been studied using a Fe tagged complex. The preparation is removed from the plasma in 8-10 days. Fifty per cent of the iron was incorporated into haemoglobin in 3-4 weeks and the iron stores replenished rapidly. Using organ scanning, the liver was confirmed as the site of primary plasma clearance, but accumulations of iron were detected in the spleen and bone marrow. Only minute quantities of radioactivity appeared in the urine. No untoward effects on iron metabolism have been detected, but reduction of the serum iron and total binding capacity to low levels 6 weeks post infusion is of interest. An attempt has been made to interpret the findings to elucidate the ferrokinetics of this method of treatment.(Summary)