Renal Blood Flow Measured By CT Perfusion Imaging: Preliminary Clinical Application

Objective: To measure the renal blood flow noninvasively by perfusion CT imaging, and to investigate its clinical application value in normal and abnormal kidney (including hydronephrosis, primary hypertension, and renal neoplasma). Methods: According to the results of physical examinations and renal functional tests, the findings of radiology and pathology, 75 cases underwent routine CT scan (precontrast CT scan and postcontrast CT scan) and perfusion CT scan, were divided into the normal group (22cases), hydronephrosis group(2leases), primary hypertension group(lScases), and renal neoplasma group(17cases). All the original images of perfusion CT scan were transferred to an outline workstation to create color perfusion maps and to measure the blood flow parameters, containing the perfusion value, peak enhancement (PE), time to peak enhancement (TTP), and mean transit time(MTT), of the renal cortex and medulla using the functional CT software. Results: (1) The time-attenuation curves of bilateral normal renal cortex and medulla are symmetric, even coincident, and the mean blood flow of renal cortex and medulla were (184.86 + 34.59)ml/100g/min and (69.92+ 24.94) ml/l00g/min respectively. Using analysis of variance, there was no gender differences in the perfusion parameters, but the Perfusion of cortex and the difference of peak enhancement between cortex and medulla was lower, and TTP of cortex was prolonged in the elder (P<0.05). (2) The mean Perfusion and PE of the cortex and medulla of obstructed kidney were lower compared to that of normal and the contralateral compensatory kidney .The cortex Perfusion and PE of the obstructed kidney were (98.04 + 47.62) ml/l00g/min and (82.90?1.81) Hu respectively; and the medulla Perfusion and PE were (41.34+ 16.28)ml/100g/min and (41.03 + 18.47) HU, P<0.01. In addition, MTT of the medulla and the difference between cortex and medulla in severe obstructed kidney also decreased significantly, which were (6.88 + 0.46) s and (28.08 +10.10)HU, P<0.05. (3) The renal cortex blood flow decreased and MTT was shorten inthe 15 patients with primary hypertension, that were (115.48+65.08) ml/l00g/minand (13.39 ?.15) s respectively, P<0.05. (4) The lesion can be distinguished clearly from the normal tissue in the perfusion CT color maps. In general, there was no blood flow in cysts and the tissues without vascular structure, low blood flow in benign lesion, high and uneven blood flow in malignancy. Conclusion: Quantitative measurement of renal blood flow using perfusion CT imaging can add useful information about renal function that is very important in clinical practice.