Consolidation Type of Bronchioloalveolar Carcinoma and Necrotizing Pneumonia: Differential Diagnosis on CTScans

PURPOSE: To determine the CT findings which distinguish consolidation-type bronchioloalveolar carcinoma fromnecrotizing pneumonia. MATERIALS AND METHOD: This study involved ten patients with pathologically-provenconsolidation-type bronchioloalveolar carcinoma and 34 with necrotizing pneumonia proven pathologically either inthe laboratory or clinically. We retrospectively analyzed CT features including the enhancement pattern ofconsolidated lung, the presence and internal density of cavity within consolidated lung, CT angiogram sign,air-bronchogram, pleural enhancement, pleural effusion, and change in extrapleural tissue and its density. RESULT: CT findings in patients with necrotizing pneumonia showed higher attenuation in marginal (94.1%) and inner(85.3%) portions in consolidated lung than in muscles (p<0.005); the presence of cavity (91.2%, p<0.05) ; cavitywith fluid or air-fluid level (77.4%, p<0.005); pleural enhancement (88.2%, p<0.00003) ; pleural effusion (33.3%,p<0.05); and change in extrapleural tissue (64.7%, p<0.05). CT findings in patients with consolidation-typebronchioloalveolar carcinoma showed lower attenuation in marginal (90.0%) and inner (60.0%) portions ofconsolidated lung than muscles (p<0.005) and of cavity containing air (100%; p<0.005). However, air-bronchogramand CT angiogram signs were not helpful in differentiating the two groups. CONCLUSION: CT can help differentiateconsolidation-type bronchioloalveolar carcinoma and necrotizing pneumonia.

Usefulness of Turbo Spin-Echo MR Imaging in Meniscal Tears of the Knee

PURPOSE: To evaluate the usefulness and diagnostic accuracy of turbo spin-echo(TSE) proton-density andT2-weighted images of meniscal tears of the knee. MATERIALS AND METHODS: We retrospectively evaluated thesensitivity, specificity, and accuracy of TSE proton density and T2-weighted images of meniscal tears confirmedarthroscopically or surgically in 47 patients(98 menisci). The routine TSE parameters used in all patients werethe dual echo sequence with sagittal proton density and T2-weighed images(4000/16, 90/5/2 [TR/effectiveTE/ETL/NEX]), and fat-suppressed coronal proton density and T2-weighted images. The chi-square test was used forstatistical analysis. RESULTS: The sensitivity, specificity, and accuracy of TSE proton density images for thedetection of meniscal tears were 93.9%, 93.8%, and 93.9%, respectively, in the medial meniscus, and 92.9%, 91.4%,and 91.8% in the lateral. On T2-weighted images the corresponding figures were 87.9%, 93.8%, and 89.8%,respectively, in the medial meniscus, and 64.3%, 91.4%, and 83.7 % in the lateral. CONCLUSION: With regard tosensitivity and accuracy, TSE proton density images of meniscal tears were superior to TSE T2-weighted images.

MR Imaging of the Combined Anterior and Posterior Cruciate Ligament Tears: Focussing on the Patterns of Injuries and Associated Findings

PURPOSE: To evaluate the patterns of injuries and frequency of associated findings on MR imaging in patients with both anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) tears; to compare the associated findings, as seen on MR imaging, in cases with both ACL and PCL tears with those with ACL or PCL tears. MATERIALS AND METHODS: Ten patients with combined ACL and PCL tears, 16 with ACL tears and 18 with PCL tears, all confirmed by arthroscopy or open surgery, were involved in this study. To identify the associated knee injuries, MR images were retrospectively evaluated. RESULTS: In ten patients with combined ACL and PCL tears, open surgery led to the identification of six complete ACL tears (60%), four partial ACL tears (40%), eight complete PCL tears (80%) and two partial PCL tears (20%). Injuries associated with these combined tears, and revealed by MR imaging, comprised six medial collateral ligament injuries (60%), six lateral collateral ligament injuries (60%), five medial meniscal injuries (50%), three lateral meniscal injuries (30%), nine bony injuries (90%), two posterior capsular injuries (20%), and three popliteus muscle injuries (30%). The frequency of popliteus muscle injury was significantly different (p<0.05, Fisher's exact test) between the group with both ACL and PCL tears and that with ACL or PCL tears. CONCLUSION: Associated findings in patients with combined ACL and PCL tears are more frequentthan in those with ACL or PCL tears. In cases involving combined ACL and PCL tears, associated findings-as seen on MR images-should thus be carefully examined.

Detection of Liver Metastases: Usefulness of Dynamic Spiral CT during the Portal Phase with a Higher IV Injection Rate of Contrast Material

PURPOSE: To evaluate the usefulness of dynamic spiral computed tomography(CT) during the portal phase with ahigher IV injection rate of contrast material in detecting hepatic metastases. MATERIALS AND METHODS: We reviewed two-phase dynamic spiral CT in 44 patients with hepatic metastases of pathologically proven primary malignancy. One hundred and fifty ml. of non-ionic contrast material was administered with a power injector at a rate of 5ml/sec., and two-phase images at 55-80 sec.(portal phase) and 2-5 min.(equilibrium phase) were obtained after thestart of bolus injection. Two phase images were compared for detectability of hepatic metastases according tosize, number and enhancement pattern. RESULTS: In cases of metastases less than 1cm, 113 lesions(100%) that showed clearly defined hypodense lesions were detected in the portal phase of dynamic CT. However, the equilibriumphase images showed hypodense lesions in 58 cases(51%) and isodense lesions in 55cases(49%). In cases of metastases 1-2cm in size, the portal phase images detected 70 hypodense lesions(92%) and six hyperdense lesions(8%). In the equilibrium phase, however, the lesions were hypodense in 54 cases(71%), hyperdense infour(5%), and isodense in 18(24%). In cases of metastases larger than 2 cm, portal phase images showed 29 hypodense lesions(97%) and one hyperdense lesion(3%). In the equilibrium phase, however, the lesions were hypodense in 25 cases(83%), hyperdense in two(7%), and mixed in three(10%). As compared with the portal phase, most metastatic lesions were detected as poorly defined hypodense or isodense lesions in the equilibrium phase and decrease in size due to peripheral enhancement. CONCLUSION: Dynamic spiral CT during the portal phase with a higher IV injection rate(5 ml/sec) of contrast material is a useful method for detecting hepatic metastases, especially small lesions less than 1cm.

Spiral CT of Hepatocellular Carcinoma: Value of Dynamic Fast Infusion of Contrast Material

PURPOSE: To assess the value of dynamic fast infusion of contrast material in the detection and diagnosis of hepatocellular carcinoma(HCC) with spiral CT. MATERIALS AND METHODS: Two-phase dynamic spiral CT was performed in 59 patients with 104 HCCs. 150ml of nonionic contrast material was injected with an automatic injector at the rateof 5 ml/sec. Two-phase images were obtained at 20-45 sec(arterial dominant phase) and 2-5 min(equilibrium phase)after the initiation of bolus injection of contrast material. The tumors were divided into three groups(5cm) according to the size and the enhancement patterns on two-phase images were compared. RESULTS: Inthe arterial phase, HCCs showed total or partial hyperattenuation in 79% of cases(82/104), isoattenuation in 12%,and hypoattenuation in 9%. In the equilibrium phase, HCCs showed hypoattenuation in 86%(89/104) and isoattenuationin 14%. The most common and characteristic enhancement patterns of HCCs were hyperattenuation in the arterialphase and hypoattenuataion in the equilibrium phase ; in the latter, capsules were demonstrated in 45% of cases. Invasions of the portal and/or hepatic vein were demonstrated in 34% of cases. CONCLUSION: Dynamic fastinfusion(5ml/sec) of contrast material(150ml) is useful in the detection and diagnosis of HCCs with spiral CT.

MRI Findings of Miliary Tuberculosis of the Brain

PURPOSE: To evaluate MRI(Magnetic Resonance Imaging) findings of miliary tuberculosis of the brain. MATERIALS AND METHODS: Six patients with miliary tuberculosis of the brain diagnosed by characteristic clinical or laboratory findings were studied with spin echo MRI before and after contrast enhancement. We retrospectively evaluated MRI findings acording to the appearance, distribution, location, and enhancement pattern of the granulomas as well as associated other abnormalities. RESULTS: In six patients, contrast-enhanced MRI of thebrain showed numerous punctate, contrast enhancing lesions scattered throughout the brain. Unenhanced MRI failed to demonstrate small granulomas except a few small foci of high signal intensity on T2-weighted images. The shapes of enhancing granulomas were homogeneous nodular enhancement in 86% of cases and small ring enhancement in 14%.98% of granulomas were smaller than 3-mm and 2% were larger. Although several lesions were located in the basalganglia, thalamus, and brain stem, the majority were located in the subpial and subarachnoid space. There was no significant difference in distribution of granulomas between the supratentorial and the infratentorial areas. Other associated abnormalities were focal meningitis in five cases and focal cerebritis in one. On chest radiograph, all patients had miliary tuberculosis in the lungs. CONCLUSION: Contrast-enhanced T1-weighted MRimaging showed numerous round, very small enhancing lesions scattered throughout the brain. The majority of lesions were located in the subpial and subarachnoid space. Contrast-enhanced T1-weighted images are helpful inthe detection and diagnosis of miliary disseminated tuberculous granulomas and meningitis.

Value of Axial 3-D Fourier Transformation GRASS MR Images in Diagnosis of Meniscal Tears of the Knee

PURPOSE: The purpose of this study is to compare the sensitivity and specificity of axial 3-D imaging with those of conventional 2-D imaging in the diagnosis of meniscal injuries. MATERIALS AND METHODS: Twenty-nine kneesof 27 patients with clinically suspected meniscal tears were imaged at a 1.5 T MR system. Conventional 2-D imagesand axial 3-D GRASS images were obtained in all cases. Arthroscopic or surgical confirmation was available in allcases and was used as the gold standard. RESULTS: Among the 29 knee-joints evaluated, 21 of 23 meniscal tears and 33 of 35 normal menisci were correctly identified with axial 3-D imaging, yielding a sensitivity of 91.3% and specificity of 94.3%. Conversely, the sensitivity was 82.6% and the specificity was 97.1% for the conventional 2-Dtechnique. A combination of both techniques yielded 95.7% sensitivity and 100% specificity in the diagnosis of meniscal tears. Of the 23 meniscal tears proven at arthroscopy or surgery, there were four discrepancies between the two techniques ; three of the four represented false-negative 2-D images and one was a false-negative axial3-D image. Of 35 normal menisci, two false-positives occurred with axial 3-D imaging and one with 2-D imaging. CONCLUSION: Despite the lack of a statistically significant difference between the efficacy of the two techniques, these results suggest that the sensitivity in the diagnosis of meniscal tears can be improved by adding thin-sliced axial 3-D GRASS imaging to conventional 2-D imaging in the limited cases with clinically suspected meniscal tears.

Preoperative Assessment of Rectal Cancer: Value of Two-Phase Dynamic CT

PURPOSE: The purpose of this study was to evaluate the utility of two-phase dynamic CT, early and equilibrium pahse, in the preoperative staging of rectal cancers. MATERIALS AND METHODS: We performed incremental dynamic CT after rectal infusion of water in 34 patients with pathologically proved rectal cancers. Two-phase dynamic CT findings were prospectively analyzed and correlated with surgical and histopathologic findings. A total of 150ml of nonionic contrast medium was intravenously administered with a power injector at a flow rate of 5ml/sec for 30 sec, and two-phase images were obtained at 30 sec(early phase) and 2 min (equilibrium phase) after bolus injection. Local tumor staging and regional lymph node were classified by TNM staging. RESULTS: All 34 rectal cancers showed a moderate to marked enhancement in the early phase and a homogeneous and prolonged enhancement of the entire lesion in the equilibrium phase. T-staging of primary tumors were 85.3%(29/34) in early phase and 70.6%(24/34) in equilibrium phase. The accuracy in determining the perirectal fat invasion of rectal cancer was 92%(23/25) in early phase, and 72%(18/25) in equilibrium phase. The sensitivity & specificity of the regional lymph node metastasis were 63.6% and 79.1% in early phase, and 54.5% and 65.2% in equilibrium phase, respectively. CONCLUSION: Early phase dynamic CT was more accurate for the preoperative staging of rectal cancer than that at equilibrium phase.