Quantitative Reconstructions for Renal Sestamibi SPECT/CT: A Modeled Comparison of 360-Degree Versus 180-Degree Acquisitions.

RATIONALE: 99m Tc-sestamibi single-photon emission computed tomography/computed tomography (SPECT/CT) is a cost-effective and accurate means of characterizing indeterminate renal masses. This is scant literature on 99m Tc-sestamibi protocol optimization.

METHODS

We investigated the difference between modeled, quantitative 180-degree and 360-degree acquisitions for 99mTc-sestamibi SPECT/CT in a cohort of 50 patients who were prospectively enrolled on a scan-and-resect protocol. Two experienced, dual-boarded observers rated each renal mass for image quality (1-5 scale) and diagnosis (benign to malignant, 1-5 scale) in a blinded, randomized order. Ordinal logistic regression was used, incorporating random intercepts for patient and reader; inter-observer variability was assessed.

RESULTS

Image quality ratings were significantly higher for 360-degree acquisitions versus 180-degree (P<0.0001; odds ratio 0.22, 95% CI 0.12-0.39). The odds ratio was 0.22 (95% CI: 0.12, 0.39). There was insufficient evidence that the modeled angle of acquisition was associated with scan positivity (P=0.17). The odds ratio was 0.67 (95% CI: 0.37, 1.19). Diagnostic positivity ratings did not differ between reconstruction angles (P=0.17; odds ratio 0.67, 95% CI 0.37-1.19).

CONCLUSIONS

Modeled 180-degree reconstructions of quantitative SPECT/CT are qualitatively inferior to quantitative reconstructions of 360-degree acquisitions, although there was no difference in the diagnostic accuracy between the reconstruction methods. These results suggest that 180-degree acquisitions are adequate for diagnosis.