Magnetic resonance imaging of regional myocardial perfusion in patients with single-vessel coronary artery disease: quantitative comparison with (201)Thallium-SPECT and coronary angiography.

The clinical value of magnetic resonance perfusion imaging (MRI) was investigated by quantitative comparison with (201)thallium-single-photon emission computed tomography ((201)TI-SPECT) and quantitative coronary angiography (QCA). Short-axis imaging was performed during dipyridamole administration in 13 patients with single-vessel coronary artery disease. Using inner and outer contours, the myocardium was divided into 30 contiguous, radial regions. Defining a perfusion defect as a region with less than 90% of maximum (201)TI intensity, nine patients had a matching perfusion defect, two had no defect on both (201)TI-SPECT or MRI, and one had a defect on (201)TI-SPECT but not on MRI. One patient had a defect on both modalities but with inaccurate localization. Three perfusion parameters were investigated: a) maximum contrast enhancement (MCE); b) slope of the signal intensity versus time curve; and c) inverse mean transit time (1/MTT). The sensitivity and specificity of MCE in the detection of perfusion abnormalities with TI-SPECT as the reference method were 71% and 71%, respectively (slope 77% and 61%, 1/MTT 44% and 70%). Furthermore, correlations were calculated per patient for the entire circumference of the short-axis myocardium. Median correlations were as follows: MCE 0.92, slope 0.91, and 1/MTT 0.40. Mismatches between (201)TI defects and defects on MRI resulted in low mean correlations (MCE 0.45, slope 0.46, and 1/MTT 0.26). There was a trend between severity of perfusion defects on MRI (using MCE) and QCA stenosis area (r = -0.56, P = 0.06). Thus, MRI and (201)TI-SPECT demonstrate fair agreement in the assessment of perfusion defects but show moderate correlation when the entire short-axis myocardium is correlated.

The cold pressor test during radionuclide ventriculography: a feasibility study in cancer patients.

To monitor the use of cardiotoxic drugs, adequate assessment of myocardial function is required. Although serial radionuclide left ventricular ejection fraction (EF) studies allow a simple and rapid assessment of the myocardial function without risk or discomfort to the patient, they appear not to be sensitive enough. Determination of the EF during cold application may be more sensitive. In this study we tested the feasibility of the cold pressor test (CPT) in relation to EF determination in 23 cancer patients. Only minor side effects were recorded. The response of heart rate to cold was similar to the response reported in healthy volunteers and patients with coronary artery disease. In selected cases EF determination during CPT appeared to be more sensitive than EF at rest. EFCPT may be an attractive alternative for EFexercise in cancer patients who cannot perform enough exercise to stress cardiac function adequately, but for a more definite conclusion a prospective comparative study is required.