Imaging of soft tissues adjacent to orthopedic hardware: comparison of 3-T and 1.5-T MRI.

OBJECTIVE: The purpose of this study was to compare metal artifact reduction techniques at 1.5-T and 3-T MRI. MATERIALS AND METHODS: A titanium plate with steel screws was placed in a freshly harvested pig leg. The leg was imaged with 1.5-T and 3-T MRI. A T2-weighted turbo spin-echo sequence was used with echo-train lengths of 8, 16, 32, and 64 and a constant readout bandwidth of 31.2 kHz. The images were compared qualitatively, and the optimal echo-train length was selected. Images were acquired at the optimal echo-train length with four different readout bandwidths. Artifact was measured quantitatively, and image quality was ranked qualitatively. The qualitatively best image acquired at 1.5 T was compared with the qualitatively highest-ranked image acquired at 3 T. RESULTS: At both 1.5 T and 3 T, optimal images of equal quality were produced at echo-train lengths of 8 and 16. At higher readout bandwidths, there was quantitatively less artifact. The qualitatively best images were acquired at a readout bandwidth of 31.2 kHz at 1.5 T and 62.5 kHz at 3 T (Cronbach's alpha=1.00). The optimal image at 3 T was qualitatively superior to that at 1.5 T. CONCLUSION: Optimizing image acquisition parameters in this phantom model resulted in similar quantitative susceptibility artifact at 3 T and 1.5 T and better qualitative images at 3 T than at 1.5 T.

NPHS2 V260E Is a Frequent Cause of Steroid-Resistant Nephrotic Syndrome in Black South African Children.

INTRODUCTION: In South Africa (SA), steroid-resistant nephrotic syndrome (SRNS) is more frequent in black than in Indian children. METHODS: Seeking a genetic basis for this disparity, we enrolled 33 Indian and 31 black children with steroid-sensitive nephrotic syndrome (SSNS) and SRNS from KwaZulu-Natal, SA; SRNS children underwent kidney biopsy. We sequenced NPHS2 and genotyped APOL1 in 15 SSNS and 64 SRNS unrelated patients and 104 controls and replicated results in 18 black patients with steroid-resistant focal segmental glomerulosclerosis (SR-FSGS). Known FSGS genes (n = 21) were sequenced in a subset of patients. RESULTS: Homozygosity for NPHS2 V260E was found in 8 of 30 black children with SRNS (27%); all 260E/E carriers had SR-FSGS. Combining SR-FSGS patients from the 2 groups, 14 of 42 (33%) were homozygous for V260E. One black control was heterozygous for V260E; no Indian patients or controls were carriers. Haplotype analysis indicated that homozygosity for V260E was not explained by cryptic consanguinity. Children with NPHS2 260E/E developed SRNS at earlier age than noncarriers (34 vs. 78 months, P = 0.01), and none achieved partial or complete remission (0% vs. 47%, P = 0.002). APOL1 variants did not associate with NS. Sequencing FSGS genes identified a CD2AP predicted pathogenic variant in the heterozygous state in 1 Indian case with SR-FSGS. CONCLUSION: NPHS2 260E/E was present in one-third of black FSGS patients, was absent in black controls and Indian patients, and affected patients were unresponsive to therapy. Genotyping V260E in black children from South Africa with NS will identify a substantial group with SR-FSGS, potentially sparing these children biopsy and ineffective steroid treatment.