99mTc-DMSA planar imaging versus dual-detector SPECT for the detection of renal cortical scars in patients with CKD-3

ObjectiveThe aim of this study was to compare planar technetium-99m-dimercaptosuccinic acid (99mTc-DMSA) cortical scintigraphy with 99mTc-DMSA single-photon emission computed tomography (SPECT) for the detection of renal cortical scars in patients with chronic kidney disease stage-3 (CKD-3). Patients and methodsData of 40 patients (mean age: 43.7±15.3 years, 29 men, 11 women) who underwent planar 99mTc-DMSA along with regional 99mTc-DMSA SPECT for the detection of renal cortical scars were prospectively evaluated. All the patients had CKD-3, with a mean serum creatinine level of 2.23±1.85 g/dl. Planar and SPECT 99mTc-DMSA images were evaluated by two nuclear medicine readers independently. Each kidney was divided into 12 cortical segments. A cortical segment was recorded as abnormal if it had reduced or absent radiotracer activity. The linear correlation coefficient (r value) for the number of abnormal segments detected between readers was calculated for planar imaging, SPECT, and between the two techniques for both the readers. ResultsFor both observers, the average correlation coefficient for SPECT (r=0.87) and planar imaging (r=0.90) was high (P<0.0001). A moderately strong linear correlation was also observed between readers for planar imaging and SPECT (r=0.78 and 0.71, P<0.0001). There was no significant difference in the average number of abnormal segments detected by planar versus SPECT imaging: 2.1 for planar imaging and 2.8 for SPECT (P=0.06, two-tailed). In 15% of patients, SPECT detected cortical defects not appreciated on planar imaging. Conclusion99mTc-DMSA renal cortical imaging using dual-head SPECT offers no statistically significant diagnostic advantage over planar imaging for the detection of cortical defects in patients with CKD-3.