Segmental and global left ventricular function assessment using gated SPECT with a semiconductor Cadmium Zinc Telluride (CZT) camera: phantom study and clinical validation vs cardiac magnetic resonance

BACKGROUND

We evaluated gated-SPECT using a Cadmium-Zinc-Telluride (CZT) camera for assessing global and regional left ventricular (LV) function.

METHODS

A phantom study evaluated the accuracy of wall thickening assessment using systolic count increase on both Anger and CZT (Discovery 530NMc) cameras. The refillable phantom simulated variable myocardial wall thicknesses. The apparent count increase (%CI) was compared to the thickness increase (%Th). CZT gated-SPECT was compared to cardiac magnetic resonance (CMR) in 27 patients. Global and regional LV function (wall thickening and motion) were quantified and compared between SPECT and CMR data.

RESULTS

In the phantom study using a 5-mm object, the regression between %CI and %Th was significantly closer to the line of identity (y = x) with the CZT (R (2) = 0.9955) than the Anger (R (2) = 0.9995, P = .03). There was a weaker correlation for larger objects (P = .003). In patients, there was a high concordance between CZT and CMR for ESV, EDV, and LVEF (all CCC >0.80, P < .001). CZT underestimated %CI and wall motion (WM) compared to CMR (P < .001). The agreement to CMR was better for WM than wall thickening.

CONCLUSION

The Discovery 530NMc provided accurate measurements of global LV function but underestimated regional wall thickening, especially in patients with increased wall thickness.

Predictive factors of effectiveness of streptokinase in deep venous thrombosis

In a prospective study, 174 patients (118 women and 56 men, average age 44 years, range 14 to 82) with proximal extensive thrombosis received streptokinase (100,000 U/hour) for an average of 2.8 days (range 0.5 to 7) through the catheter of a temporary caval filter. Twenty-seven of 45 (60%) patients with nonocclusive clots were completely free of clots at the second phlebography versus 17 of 116 (14%) with occlusive clots (p less than 0.001). Among nonocclusive clots, proximal ones (caval, iliac and femoral) were more easily lysed than popliteal clots (88 of 116 [76%] vs 26 of 58 [45%]; p less than 0.001). In 41 of 132 (31%) patients, a daily injection of contrast medium through the filter-carrying catheter enabled the observation of a clot in the filter, which was lysed by streptokinase. Seventy patients with follow-up greater than 2 years (median 34 months) were examined clinically. Nineteen of 22 (86%) patients with venograms free of clots at discharge were free of clinical sequelae versus 16 of 48 (33%) without normal venograms (p less than 0.001). It is concluded that: (1) in the case of occlusive clots, only a few patients were normalized after streptokinase; (2) proximal nonocclusive clots were most effectively lysed; (3) when venograms were free of clots at discharge, the majority of patients did not have venous sequelae at follow-up; and (4) embolic migration seems to occur frequently with streptokinase.

Use of a new removable vena cava filter in order to prevent pulmonary embolism in patients submitted to thrombolysis

The authors present a removable vena cava filter that may be introduced percutaneously, is atraumatic to the venous wall, and permits the simultaneous use of thrombolytic therapy. Sixty-five patients were studied: 42 cases of pulmonary embolism with threatening venous thrombosis; 23 cases of phlebitis associated with an ilio-caval thrombus without pulmonary embolism. The filter was introduced 38 times femorally and 27 times by a jugular approach. In 16 cases (24.6%) clots broke loose, were effectively caught by the filter, and were progressively dissolved during thrombolytic therapy. The filter remained in place on average 4.5 +/- 1.2 days. The filter was removed in all cases without provoking the recurrence of pulmonary embolism. Two deaths, not related to pulmonary embolism, occurred during hospitalization. Phlebography, performed in all cases before and after treatment, showed a significant decrease of the phlebographic score (10.88 +/- 0.82 vs 6.77 +/- 0.86, P less than 0.001). The same was observed in 40 patients who underwent a pulmonary angiography before and after treatment (Miller index = 17.04 +/- 0.73 vs 5.49 +/- 0.87, P less than 0.0001). After removal of the filter, no sign of pulmonary embolism was detected on lung scan in the 23 patients with ilio-caval thrombus alone. More than 5 g (100 ml)-1 of haemoglobin was lost by 15.38% of patients. All patients were followed-up for a mean of 7.12 +/- 1.3 months; in no case was there any clinical recurrence of pulmonary embolism. Thus this device allows an effective temporary filtering of the vena cava.(ABSTRACT TRUNCATED AT 250 WORDS)