Diagnostic value of apparent diffusion coefficient (ADC) in assessment of pituitary macroadenoma consistency

BackgroundPre-operative assessment of macroadenoma consistency is helpful for proper surgical planning. DWI correlated with ADC value adding information about the tumor consistency that cannot be obtained with cMRI.Patients and methodsThirty patients with pituitary adenomas were examined by MRI including cMRI (conventional magnetic resonance) and DWI (diffusion weighted imaging) with ADC value measurement. Diagnosis was correlated with intra-operative finding and histopathology.ResultsAccording to ADC values, we classified our cases into three groups of macroadenoma consistency; Group A (Soft tumors = 22/30) had mean ADC value of 0.482 × 10−3 mm2/s, Group B (intermediate consistency = 5/30) had mean ADC value of 0.730 × 10−3 mm2/s and Group C (Firm adenomas = 3/30) with mean ADC value of 0.992 × 10−3 mm2/s. Diagnostic overlap was detected in one case of group A and 2 cases of group B. The sensitivity, specificity, PPV, NPD and accuracy of ADC values were 80%, 88%, 57.1% and 95.7% at ADC 0.7 × 10−3 mm2/s and 100%, 88%, 62.5% and 100% at ADC 0.6 × 10−3 mm2/s respectively.ConclusionDWI that correlated with ADC value should be included in routine pre-operative assessment of macroadenoma consistency. We recommend a cut off value of 0.6 × 10−3 mm2/s, for accurate discrimination of the intermediate/soft macroadenomas from firm adenomas.