We evaluated the predictive capacity of 99mTc-HMPAO SPECT for clinical outcome during a follow-up period of 12 mo after mild head injury.
Methods: We prospectively evaluated 136 patients with mild head injury who underwent initial SPECT imaging (SPECTO) within 4 wk after the trauma. Re-evaluations were made 2.9-3.3 mo (T3mo), 5.7-6.3 mo (T6mo) and 11.9-12.6 mo (T12mo) postinjury. All patients with an abnormal SPECT underwent a repeat study at the subsequent time of evaluation. Patients with a previously normal SPECT scan did not undergo a repeat study. Clinical reassessments (CLIN) were performed as long as the earlier study had been positive or until patients were completely asymptomatic.
Results: During all follow-up evaluations, SPECT had a high sensitivity and negative predictive value, increasing from 91% and 89%, respectively, at T3mo to 100% at T6mo and at T12mo. Clinical normalization occurred earlier than scintigraphic normalization. However, at 12 mo postinjury, we observed considerable improvement in the specificity and positive predictive value of SPECT (85% and 83%, respectively). The persistent lesions on the SPECT scan were related to their severity and to localization in the frontal cortex.
Conclusion: A normal 99mTc-HMPAO SPECT scan is a reliable tool in the exclusion of clinical sequelae of mild head injury. At 12 mo postinjury, a positive SPECT study is also a reliable predictor for clinical outcome.