Pediatric 99mTc-DMSA SPECT performed by using iterative reconstruction with isotropic resolution recovery: improved image quality and reduced radiopharmaceutical activity.
OBJECTIVE
To compare two methods of reconstructing technetium 99m (99mTc) dimercaptosuccinic acid (DMSA) renal single photon emission computed tomographic (SPECT) data--ordered subset expectation maximization with three-dimensional resolution recovery (OSEM-3D) and filtered back projection (FBP)--in children in terms of improving image quality and reducing the radiopharmaceutical activity and radiation dose.


METHODS
The institutional review board approved this retrospective study and waived the requirement for informed patient consent. Fifty sequential pediatric patient 99mTc-DMSA SPECT studies of 98 kidneys were retrospectively analyzed by using a dual-detector gamma camera. FBP reconstruction with data from both detectors was compared with OSEM-3D reconstruction with half the gamma photon counts (ie, data from only one detector). Two nuclear medicine physicians blinded to the patients' medical histories and reconstruction techniques evaluated the studies. Scores for image quality, renal size, and relative function were compared by using paired t tests. Total scores for renal cortical defects were compared by using the Wilcoxon signed rank test. The kappa coefficient was calculated as an indicator of the concordance between the OSEM-3D and FBP reconstruction methods.


RESULTS
Image quality was significantly enhanced with OSEM-3D (P < .001, paired t test). Cortical defects were identified better on OSEM-3D images than on FBP images. Of the 98 kidney SPECT studies analyzed, 19 showed identical cortical defects and 75 showed none at both OSEM-3D and FBP. In four kidneys, OSEM-3D depicted cortical defects that were not seen with FBP. No significant difference in relative renal function between the two methods was observed (P = .973).


CONCLUSIONS
Compared with FBP, OSEM-3D yielded superior image quality in the evaluation of 99mTc-DMSA renal SPECT data, with the potential for markedly reduced radiation doses and/or shorter scanning times for patients.
Sheehy
Niall
N
Division of Nuclear Medicine, Department of Radiology, Children's Hospital Boston and Harvard Medical School, 300 Longwood Ave, Boston, MA 02115, USA.
Tetrault
Tracy A
TA
Zurakowski
David
D
Vija
A Hans
AH
Fahey
Frederic H
FH
Treves
S Ted
ST
D000293:Adolescent; D000465:Algorithms; D016880:Anisotropy; D001822:Body Burden; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007223:Infant; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D008297:Male; D010363:Pattern Recognition, Automated / Q000379:methods*; D011829:Radiation Dosage; D011866:Radioisotope Renography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D055815:Young Adult
D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid