Optimization of combined CT pulmonary angiography and renal venography for the detection of venous thromboembolism in patients with nephrotic syndrome / 中华放射学杂志

ABSTRACT

Objective To optimize combined CT pulmonary angiography (CTPA) and renal venography (rCTV) and to evaluate its value for the detection of venous thromboembolism in patients with nephrotic syndrome (NS).Methods Ninety NS patients suspected of venous thromboembolism because of abnormal D-dimer value were included in this prospective study.The first 45 patients were defined as group 1 (protocol 1).These patients underwent CTPA,then rCTV 25 s after CTPA,last inferior vena cava scanning after another 25 s.The following 45 patients as group 2 (protocol 2).These patients underwent CTPA and then inferior vena cava scanning 50 s after CTPA,3 patients in group 2 were excluded because of unavailable CTPA or rCTV.Vessel enhancement of CTPA and rCTV,and radiation doses for two protocols were compared with independent sample student t test.Incidence and distribution of pulmonary embolism and renal vein thrombosis were recorded and compared by using Chi-square test.Results Enhancement values of pulmonary trunk for groups 1 and 2 were (335.5 ± 111.3) and (335.0 ± 76.0) HU,right renal vein were (142.7 ±33.3) and (140.7 ±25.9) HU,left renal vein were (141.6 ±26.4) and (138.8 ±33.6) HU respectively,without any statistical difference (t values were 0.026,0.322 and 0.452,P ＞0.05).Radiation dose to the patients receiving protocol 2 were lower than that of patients receiving protocol 1 [volume CT index,(19.7 ± 4.3) vs (13.6 ± 3.0) mGy; dose length product,(1019.9 ± 878.5) vs (532.0 ± 132.9) mGy · cm; both P ＜0.01].Of 87 NS patients,44 venous thromboembolism events were detected,resulting in the incidence of 50.6％ (44/87),including pulmonary embolism in 19 patients,renal vein thrombosis and pulmonary embolism in 17,renal vein thrombosis in 7,and inferior vena cava in one patient.The detection rate were 48.9％ (22/45) and 52.4％ (22/42),there was no significant difference (x2 =0.106,P =0.745).Conclusion Combined CTPA and rCTV with protocol 2 (CTPA and inferior vena cava phase scanning 50 s after CTPA) is suitable to clinical application and pulmonary embolism is the most common thromboembolism complication in NS patients.