Intravoxel incoherent motion imaging and dynamic susceptibility contrast perfusion MRI in differentiation between recurrent intracranial tumor and treatment-induced changes

PURPOSE: To compare intravoxel incoherent motion (IVIM) imaging to dynamic susceptibility-weighted contrast (DSC) perfusion MRI in differentiating tumor recurrence from treatment-induced changes. METHODS: Our prospective study included patients previously treated with radiotherapy for intracranial tumors who later developed a new or increasing contrast-enhancing lesion. The final diagnosis was based on neuropathology or 6-month follow-up. MR examinations were performed for calculation of the perfusion fraction (f) using the IVIM technique and relative blood volume (rCBV) using DSC perfusion. Measurements of f and rCBV were made by two independent readers in hotspots when possible, but otherwise in the whole enhancing region. Measures of rCBV were normalized to the contralateral region. Receiver operating characteristics (ROC) analysis was performed. RESULTS: Sixty patients (35 men, median age 49, range 20-77) were evaluated. Forty-four patients had tumor recurrence and 16 had treatment-induced changes. Mean f was 0.090 for tumors and 0.058 for treatment-induced changes (p = 0.002). Mean rCBV was 3.52 and 1.79, respectively (p = 0.002). The area under the curve (AUC) in the ROC analysis was 0.72 for f and 0.77 for rCBV. Cutoff values of 0.073 for f and 2.26 for rCBV yielded equal values for sensitivity (73%), specificity (75%), and accuracy (73%). The 90th percentile value of rCBV was 4.77 for tumors and 2.53 for treatment-induced changes (p = 0.0004) and yielded the highest AUC (0.79) and a sensitivity/specificity/accuracy of 80%/75%/78% at cutoff value 3.25. CONCLUSION: The accuracy of the IVIM parameter f is similar to that of rCBV in differentiating tumor recurrence from treatment-induced changes.