RESUMO
OBJECTIVE: To evaluate the diagnostic accuracy of perfusion computed tomography (CTP) in differentiating between brain abscess and necrotic tumor. MATERIAL AND METHOD: Prospective study was performed in patients suspected of a space taking lesion in the brain. CTP was done at the suspected levels and post-processing measurement of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and permeability surface index (PS) were evaluated at ring enhanced area, central non-enhanced area, edema and contralateral normal brain. RESULTS: Seventeen patients with 21 lesions were studied. Of the 21 lesions, 12 were abscess and nine were tumors. By comparing means, only MTT at the ring enhanced area showed statistically significant difference between brain abscess and tumor (p = 0.009, 95% CI = 1.403 to 4.900). When ratio of CBV, CBF and MTT of the ring enhanced area and contralateral normal brain were analyzed (CBVr, CBFr, MTTr respectively), there were significant differences of CBVr and CBFr between the two groups (p = 0.003, 95% CI = -4.266 to -1.051 and p = 0.006, 95% CI = -9.934 to -1.969 respectively). With the threshold of CBVr more than or equal to 1.5 and CBFr more than or equal to 1, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for diagnosis of tumor were 100%, 75%, 75%, 100%, and 85.7% respectively. CONCLUSION: The CTP was shown to be useful in differentiating brain abscess from tumor. With CBVr less than 1.5, tumor can be excluded.
RESUMO
OBJECTIVE: To assess agreement in detection of lumbar disc herniation (LDH) between limited and full protocol MRI. MATERIAL AND METHOD: 123 patients who requested lumbar MRI for diagnosis of disc herniation were assessed The full protocol MRI composed of sagittal T1-wi, sagittal T2-wi and axial T2-wi was performed on each patient. The sagittal T2-wi was selected as the limited protocol MRI. The limited and full protocols MRI of each patient were separately interpreted by three neuroradiologists to assess disc herniation and nerve root compression. The consensus results of limited and full protocol were compared. The diagnostic performance of each protocol was analyzed using surgery as the gold standard. RESULTS: There were 62 females and 61 males enrolled into the study between the age of 21-60 years old (means = 42.91 years). The duration of pain was 1-204 months (mean = 31.20 months). The degree of severity was mild in 23.58%, moderate 45.52% and severe 30.89% of cases. Thirty-three cases were operated on. For detection of LDH, the limited protocol gave the same interpretation results as the full protocol (0 = 1.04, 95%CI = 0.94, 1.14 with accepted range of 0.95-1.05). In nerve root compression, the limited protocol was not accurate as the full protocol (0 = 0.75, 95%CI = 0.87, 0.63). The sensitivity, specificity, accuracy, PPV, NPV, and LR+ in the surgical group of limited protocol in diagnosis of LDH were 82.61%, 80%, 81.82%, 90.48%, 60.67%, 4.13 and in nerve root compression were 54.84%, 100%, 57.58%, 100%, 12.5% respectively. The same statistics of full protocol MRI in diagnosis of LDH were 82.61%, 70.80%, 78.79%, 86.36%, 63.64%, 2.75 and of nerve root compression were 80.65%, 100%, 81.82%, 100%, 25% respectively. The sensitivity and specificity in diagnosis of LDH were not different in both protocols but the sensitivity of nerve root compression was statistically significant different (p < 0.013, 95%CI = -0.33, -0.25). CONCLUSION: The authors concluded that limited protocol MRI may replace full protocol MRI in diagnosis of LDH but not in nerve root compression.