Zhao Long, Presenter: Nothing to Disclose

Jiayi Liu, Abstract Co-Author: Nothing to Disclose

Zhanming Fan, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to compare R2* value of renal artery stenosis (RAS) patients with the degree of RAS of its own and R2* value of control group respectively, and therefore evaluate different levels of renal hypoxia by BOLD MRI.

We compared 51 renal arteriosclerosis kidneys with 32 healthy kidneys of volunteers. We also compared 4 subgroups of renal arteriosclerosis kidneys, 16 without obvious RAS, 6 with mild RAS, 9 with moderate RAS and 20 with severe RAS. BOLD signal was measured in the cortex and medulla by a 3.0T MR scanner. The severity of vascular occlusion was determined by intervention.

For all groups, medulla R2* values, reflecting the deoxyhemoglobin, were higher than cortex R2* values. Both cortex and medulla R2* values of renal arteriosclerosis kidneys (21.14±4.90/s, 36.25±8.04/s) were higher than corresponding R2* values of control group (18.23±1.77/s, 29.61±2.26/s) (P<0.05), and a more sensitive change was found in medulla. For RAS subgroups, medulla R2* values for severe RAS (44.20±6.01/s) elevated as compared with unobstructed, mild, moderate stenosis subgroups (29.87±3.92/s, 33.15±2.42/s, 31.98±4.28/s) (P<0.05), but cortex R2* values for severe RAS(24.06±5.94/s) were found no significant difference from mild, moderate stenosis subgroups(20.20±2.01/s, 19.14±1.86/s) while it was higher than unobstructed subgroup(18.96±3.62/s) (P<0.05). Besides, combing mild and moderate RAS as one group, both cortex and medulla R2* values of this group (19.56±1.92/s, 32.44±3.59/s) elevated as compared with control group (P<0.05).

This study shows that BOLD MR can noninvasively detect different levels of renal hypoxia induced by RAS with different severities of vascular occlusion. It can play an important role in estimation of kidney oxygenation changes when vascular occlusion overwhelms the capacity of the kidney to adapt to reduced blood flow. R2* value may become an index to identify the severity of renal hypoxia and parenchymal injury.

BOLD MRI is an effective and noninvasive method to evaluate the oxygenation state of kidney. It can play an important role in estimation of kidney oxygenation changes when RAS exists. BOLD MRI is a sensitive tool which can be used to detect ischemia and anoxia of medulla of kidney.

Long, Z, Liu, J, Fan, Z, Cortical and Medulla Oxygenation Evaluation of Kidneys with Renal Artery Stenosis by BOLD MRI Comparing with Healthy Volunteers.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009240.html