Prognostic value of perfusion MR imaging of high-grade astrocytomas: long-term follow-up study

Abstract

Background and purpose: Although the prognostic value of perfusion MR imaging in various gliomas has been investigated, that in high-grade astrocytomas alone has not been fully evaluated. The purpose of this study was to evaluate retrospectively whether the tumor maximum relative cerebral blood volume (rCBV) on pretreatment perfusion MR imaging is of prognostic value in patients with high-grade astrocytoma.

Materials and methods: Between January 1999 and December 2002, 49 patients (30 men, 19 women; age range, 23-76 years) with supratentorial high-grade astrocytoma underwent MR imaging before the inception of treatment. The patient age, sex, symptom duration, neurologic function, mental status, Karnofsky Performance Scale, extent of surgery, histopathologic diagnosis, tumor component enhancement, and maximum rCBV were assessed to identify factors affecting survival. Kaplan-Meier survival curves, the logrank test, and the multivariate Cox proportional hazards model were used to evaluate prognostic factors.

Results: The maximum rCBV was significantly higher in the 31 patients with glioblastoma multiforme than in the 18 with anaplastic astrocytoma (P < .03). The 2-year overall survival rate was 67% for 27 patients with a low (< or =2.3) and 9% for 22 patients with a high (>2.3) maximum rCBV value (P < .001). Independent important prognostic factors were the histologic diagnosis (hazard ratio = 9.707; 95% confidence interval (CI), 3.163-29.788), maximum rCBV (4.739; 95% CI, 1.950-11.518), extent of surgery (2.692; 95% CI, 1.196-6.061), and sex (2.632; 95% CI, 1.153-6.010).

Conclusion: The maximum rCBV at pretreatment perfusion MR imaging is a useful clinical prognostic biomarker for survival in patients with high-grade astrocytoma.

Fig 1.

ROC curves to determine the optimal maximum rCBV cutoff for predicting the 2-year survival. At a critical test cutoff value of rCBV = 2.3, sensitivity and specificity for distinguishing the 2-year survival are 95% and 68%, respectively. Area under the curve is 0.829.

Fig 2.

The relationship between maximum rCBV values and survival time in 49 patients with high-grade astrocytoma. A cutoff value of 2.3 for maximum rCBV (dotted line) was determined on the basis of an ROC analysis result to best discriminate patients with and without 2-year survival. ○ indicates surviving patients with AA; •, patients with AA who died; ▵, surviving patients with GBM; ▴, patients with GBM who died.

Fig 3.

Kaplan-Meier survival curves for patients with GBM or AA with low rCBV (≤2.3) or high rCBV (>2.3). For patients with GBM and AA, the overall survival rate was significantly lower for patients with high rCBV (>2.3) than for those with low rCBV (≤2.3) (P = .013 and P < .001, respectively). ○ indicates surviving patients with AA; •, patients with AA who died; ▵, surviving patients with GBM; ▴, patients with GBM who died.

Fig 4.

Transverse MR images obtained in a 71-year-old woman with anaplastic astrocytoma. A and B, T2-weighted (A) (TR/TE, 3600/96 ms) and contrast-enhanced T1-weighted (B) (TR/TE, 670/14 ms) images showing a heterogeneous signal-intensity lesion with slightly enhanced areas in the left basal ganglia. C, Transverse rCBV map showing intratumoral high-perfusion areas (arrow). The maximum rCBV value within the tumor is 2.4. This patient died 25 months after the initial MR imaging study.

Fig 5.

Transverse MR images obtained in a 43-year-old woman with anaplastic astrocytoma. A and B, T2-weighted (A) (TR/TE, 3600/96 ms) and contrast-enhanced T1-weighted (B) (TR/TE, 670/14 ms) images showing a heterogeneous signal-intensity lesion with patchy enhanced areas in the left temporal lobe. C, Transverse rCBV map showing slight high-perfusion areas (arrow) in the medial portion of the temporal lesion. The maximum rCBV value within the tumor is 1.9. This patient survived 65 months after the initial MR imaging study.