Arvind Sonik

Stanford University, Palo Alto, California, United States

Are you Arvind Sonik?

Claim your profile

Publications (3)3.91 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE MRI for pediatric bone tumors and osteomyelitis requires joint-to-joint anatomic coverage, which can be time-consuming for long bones. This study assesses the potential of a fast single sequence MRI protocol based on a two-echo modified 2-point Dixon technique that yields volumetric (3D) fat, water, in-phase, and opposed-phase T2-weighted images. METHOD AND MATERIALS 17 consecutive patients were identified retrospectively with lesions of a long bone that underwent conventional (longitudinal T1, short-axis T1 and fat-suppressed T2 sequences) and 2-point 3D MRI. Two radiologists independently assessed quality of fat suppression, lesion detection and extent, value of in/opposed phase images, joint/neurovascular involvement. RESULTS No case had significant fat suppression failure on 3D images, whereas minor fat suppression failure was seen in 18% (95% C.I. 0-38%). No case had major fat sat failure. Overall fat suppression was superior in 3D exams (binomial test, p <0.001), but no statistically significant difference in fat suppression near the lesion was demonstrated (p = .33). In/opposed phase imaging was useful in 47% (95% C.I. 21-73%). No bone lesion was seen by conventional imaging alone, and no significant difference in the longitudinal measurement of intraosseous bone lesion extent between two methods was demonstrated (p = .23, paired t-test). With conventional MRI as the gold standard for extraosseous extension of bone lesions, 3D had a sensitivity of 100%, specificity of 90% and high agreement with 2D (Cohen’s kappa = 0.88). No cases had joint or neurovascular involvement, so assessment of these features is limited. Mean total scan times for 2D sequences and 3D were 17.6 and 6.5 minutes, respectively CONCLUSION This preliminary study indicates a single-sequence technique may permit fast MRI evaluation of pediatric bone tumors and osteomyelitis in terms of lesion detection, characterization, and extent. Further study should be aimed at assessing accuracy of assessment of neurovascular and joint involvement. CLINICAL RELEVANCE/APPLICATION This preliminary study indicates a single-sequence technique may permit fast MRI evaluation of pediatric bone tumors and osteomyelitis in terms of lesion detection, characterization, and extent.
    No preview · Conference Paper · Dec 2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pediatric body MRI exams often cover multiple body parts, making the development of broadly applicable protocols and obtaining uniform fat suppression a challenge. Volumetric T2 imaging with Dixon-type fat-water separation might address this challenge, but it is a lengthy process. We develop and evaluate a faster two-echo approach to volumetric T2 imaging with fat-water separation. A volumetric spin-echo sequence was modified to include a second shifted echo so two image sets are acquired. A region-growing reconstruction approach was developed to decompose separate water and fat images. Twenty-six children were recruited with IRB approval and informed consent. Fat-suppression quality was graded by two pediatric radiologists and compared against conventional fat-suppressed fast spin-echo T2-W images. Additionally, the value of in- and opposed-phase images was evaluated. Fat suppression on volumetric images had high quality in 96% of cases (95% confidence interval of 80-100%) and were preferred over or considered equivalent to conventional two-dimensional fat-suppressed FSE T2 imaging in 96% of cases (95% confidence interval of 78-100%). In- and opposed-phase images had definite value in 12% of cases. Volumetric fat-water separated T2-weighted MRI is feasible and is likely to yield improved fat suppression over conventional fat-suppressed T2-weighted imaging.
    No preview · Article · Jul 2011 · Pediatric Radiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Follow-up skeletal surveys have been shown to improve the rate of fracture detection in suspected cases of non-accidental trauma (NAT). As these studies are performed in a particularly radiosensitive population, it is important to evaluate if all of the (approximately 20) radiographs obtained at repeat skeletal survey are clinically useful. Our goal was to evaluate if certain radiographs can be excluded at follow-up skeletal survey without compromising the clinical efficacy. This retrospective study included 22 cases of suspected NAT (average age 3.8 months, range 0.7-15 months) in which patients received both initial and follow-up bone surveys. The follow-up survey was performed an average of 16.7 days (range 11-29 days) after the initial survey. Radiographs were reviewed by 2 pediatric radiologists, with discrepancies resolved by consensus. In addition, we combined our data with data from all known previously published reports of follow-up skeletal surveys for NAT for meta-analysis. A total of 36 fractures were found on the initial bone survey in 16/22 patients (73%). Six patients had no fractures detected at initial survey. Follow-up bone surveys demonstrated an additional 3 fractures (2 extremities and 1 rib) in 3/22 cases (14%); 1 was in a patient whose initial survey was negative. No additional fractures in the skull, spine, pelvis, feet, or hands were detected in any case. In combination with patients reported in the literature (194 patients total) no new fracture of the skull, spine, pelvis, or hands was detected at follow-up survey. The skull, spine and pelvis radiographs are the highest dose-exposure studies of the skeletal survey. If no injury is detected or suspected in the pelvis, spine, hands, or skull at initial bone survey for suspected NAT, a limited follow-up skeletal survey which excludes the pelvis, lateral spine, hands, and skull should be considered to limit radiation exposure without limiting diagnostic information.
    No preview · Article · Oct 2010 · Child abuse & neglect