In suggestive clinical presentations, the diagnosis of constrictive pericarditis is confirmed by the haemodynamic findings of impaired ventricular filling (diastole). In this study of 15 patients with pure constrictive pericarditis, the diagnosis value of two non-invasive techniques little used in this indication until now was examined: radionuclide ventriculography (RV) and magnetic resonance imaging (MRI). The RV provides a "functional" diagnosis through the analysis of global and segmental left ventricular filling whilst MRI provides anatomical details of the pericardial thickening. Diastolic dysfunction on RV presented as an increased early diastolic filling time as shown by a shortening of the interval to third filling T1/3R (p < 0.0001), an increased peak diastolic E wave velocity (p < 0.01) and early onset (p < 0.001), increased one third (FR 1/3) and mid (FR 1/2) diastolic filling fractions (p < 0.01) and of the E wave velocity to maximal systolic ejection velocity (S) ration (p < 0.01). The atrial contribution to filling in end diastole decreased (NS). Asynchronous filling, shown by dispersion of the times of onset of segmental early diastolic E peak velocities (delta tE) or of one third diastolic filling delta T1/3R, decreased. Seven patients underwent MRI. Pericardial thickening was present in all patients. The pericardium varied from 6 to 14 mm thick (normal 2.5 +/- 0.7 mm), without any systolo-diastolic variation. The thickening was seen as a dark low intensity signal, indicating the fibro-calcific character of the tissues. Sagittal and coronal views clearly demonstrated the non-uniformity of pericardial thickening.(ABSTRACT TRUNCATED AT 250 WORDS)