The effect of backpacks on the lumbar spine in children: a standing magnetic resonance imaging study.

STUDY DESIGN: This study is a repeated measures design to measure the lumbar spine response to typical school backpack loads in healthy children. The lumbar spine in this setting was measured for the first time by an upright magnetic resonance imaging (MRI) scanner. OBJECTIVE: The purpose of this study is to measure the lumbar spine response to typical school backpack loads in healthy children. We hypothesize that backpack loads significantly increase disc compression and lumbar curvature. SUMMARY OF BACKGROUND DATA: Children commonly carry school backpacks of 10% to 22% bodyweight. Despite growing concern among parents about safety, there are no imaging studies which describe the effect of backpack loads on the spine in children. METHODS: Three boys and 5 girls, age 11 +/- 2 years (mean +/- SD) underwent T2 weighted sagittal and coronal MRI scans of the lumbar spine while standing. Scans were repeated with 4, 8, and 12 kg backpack loads, which represented approximately 10%, 20%, and 30% body weight for our sample. Main outcome measures were disc compression, defined as post- minus preloading disc height, and lumbar asymmetry, defined as the coronal Cobb angle between the superior endplates of S1 and L1. RESULTS: Increasing backpack loads significantly compressed lumbar disc heights measured in the midline sagittal plane (P < 0.05, repeated-measures analysis of variance [ANOVA]). Lumbar asymmetry was: 2.23 degrees +/- 1.07 degrees standing, 5.46 degrees +/- 2.50 degrees with 4 kg, 9.18 degrees +/- 2.25 degrees with 8 kg, and 5.68 degrees +/- 1.76 degrees with 12 kg (mean +/- SE). Backpack loads significantly increased lumbar asymmetry (P < 0.03, one-way ANOVA). Four of the 8 subjects had Cobb angles greater than 10 degrees during 8-kg backpack loads. Using a visual-analogue scale to rate their pain (0-no pain, 10-worst pain imaginable), subjects reported significant increases in back pain associated with backpack loads of 4, 8, and 12 kg (P < 0.001, 1-way ANOVA). CONCLUSION: Backpack loads are responsible for a significant amount of back pain in children, which in part, may be due to changes in lumbar disc height or curvature. This is the first upright MRI study to document reduced disc height and greater lumbar asymmetry for common backpack loads in children.

Tc-99m Sestamibi Scintimammography for the Evaluation of Breast Masses in Patients with Radiographically Dense Breasts.

The objective of this study was to evaluate the usefulness of technetium-99m sestamibi (MIBI) scintimammography for the diagnosis of breast cancer in patients with palpable breast masses that cannot be adequately evaluated by mammography due to the presence of radiographically dense breasts. At 5 minutes after intravenous injection of MIBI, scintimammograms were obtained in 80 patients who had grade 3 or 4 glandular density on mammograms and a palpable breast mass. Excisional biopsy or FNA biopsy was obtained in 68 lesions in 67 patients. Scintimammography (22 true positive, 4 false positive, 41 true negative, 1 false negative) resulted in a sensitivity of 95.6%, specificity 91.1%, positive predictive value 84.6%, and negative predictive value 97.6%. Mammography (19 true positive, 21 false positive, 24 true negative, 4 false negative) resulted in a sensitivity of 73.9%, specificity 53.3%, positive predictive value 44.7%, and negative predictive value 80%. MIBI scintimammography has a higher sensitivity and specificity than mammography in patients with radiographically dense breasts. It is useful as an adjunct to mammography in those patients with radiographically dense breasts for the characterization of palpable masses. Although sensitivity of mammography in this cohort was high, its specificity was significantly lower than scintimammography. If validated in prospective studies it could provide a safe way of avoiding a breast biopsy in patients with benign findings on clinical exam, mammography, and needle aspiration cytology.