Identifying the most infectious lesions in pulmonary tuberculosis by high-resolution multi-detector computed tomography.

OBJECTIVE: This study aimed to determine whether characteristics detected by multi-detector computed tomography (MDCT) were predictive of highly infectious, smear-positive, active pulmonary tuberculosis (PTB). METHODS: Among 124 patients with active PTB, 84 had positive (group 1) and 40 had negative (group 2) smear results for acid-fast bacilli. Multiplanar MDCT, axial conventional CT and chest X-ray images were analysed retrospectively for morphology, number, and segmental (lobe) distribution of lesions. RESULTS: By multivariate analysis, consolidation over any segment of the upper, middle, or lingual lobes, cavitations, and clusters of nodules were associated with group 1, while centrilobular nodules were predictive of group 2. Using five independent variables associated with risk in group 1, a prediction model was created to distinguish between group 1 and group 2. ROC curve analysis showed an area under the curve of 0.951 +/- 0.021 for this prediction model. With the ideal cutoff point score of 1, the sensitivity, specificity, and positive predictive values were 84.5%, 97.5%, and 98.0%, respectively. CONCLUSIONS: A model to predict smear-positive active PTB on the basis of findings from MDCT may be a useful tool for clinical decisions about isolating patients pending sputum smear results.

Effective ultrasonographic predictor for the diagnosis of acute lobar nephronia.

BACKGROUND: Correct identification of acute lobar nephronia (ALN) is necessary to prevent progression to renal abscess. The goal of this retrospective study was to determine whether the sonographic finding of severe nephromegaly (i.e. renal length greater than mean + 3 sd) is a preselection criterion for computed tomographic (CT) scanning in diagnosing pediatric ALN among children with an acute upper urinary tract infection. DESIGN/METHODS: We evaluated a new imaging work-up scheme to detect pediatric ALN. All patients with urinary tract infection were evaluated with ultrasonography. If a markedly enlarged kidney or focal mass was present sonographically, CT scanning was done immediately. CT scanning was also performed when the patient had borderline nephromegaly and remained febrile for 72 h after start of antibiotic treatment. ALN diagnosis was made on the basis of positive CT findings. RESULTS: Thirty patients with ALN (13 left, 7 right, 10 bilateral) and one with acute pyelonephritis were identified. ALN in all patients resolved after 3 weeks of antibiotic treatment. Thirty-nine of the 62 kidneys evaluated showed severe nephromegaly, and 10 had focal renal masses. With CT diagnosis of ALN as the reference standard, the sensitivity of severe nephromegaly was 90.0% and the specificity was 86.4%. When the focal renal mass was added as a combining predictor, the sensitivity further increased to 95%. CONCLUSIONS: Pediatric ALN was effectively predicted using sonographic findings of severe nephromegaly and/or focal mass before CT scanning.

High-resolution CT for identify patients with smear-positive, active pulmonary tuberculosis.

PURPOSE: This study evaluates the use of high-resolution computed tomography (HRCT) to differentiate smear-positive, active pulmonary tuberculosis (PTB) from other pulmonary infections in the emergency room (ER) setting. METHODS: One hundred and eighty-three patients diagnosed with pulmonary infections in an ER were divided into an acid fast bacillus (AFB) smear-positive, active PTB group (G1=84) and a non-AFB smear-positive, pulmonary infection group (G2=99). HRCT images from a 64-Multidetector CT were analyzed, retrospectively, for the morphology, number, and segmental distribution of pulmonary lesions. RESULTS: Utilizing multivariate analysis, five variables were found to be independent risk factors predictive of G1: (1) consolidation involving the apex segment of right upper lobe, posterior segment of the right upper lobe, or apico-posterior segment of the left upper lobe; (2) consolidation involving the superior segment of the right or left lower lobe; (3) presence of a cavitary lesion; (4) presence of clusters of nodules; (5) absence of centrilobular nodules. A G1 prediction score was generated based on these 5 criteria to help differentiate G1 from G2. The area under the receiver operating characteristic (ROC) curve was 0.96 ± 0.012 in our prediction model. With an ideal cut-off point score of 3, the specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) are 90.9%, 96.4%, 90.0% and 96.8%, respectively. CONCLUSION: The use of this AFB smear-positive, active PTB prediction model based on 5 key HRCT findings may help ER physicians determine whether or not isolation is required while awaiting serial sputum smear results in high risk patients.

Association between gallium-67 uptake by lung foci and sputum smear status in patients with pulmonary tuberculosis.

OBJECTIVES: Rapid determination of the inflammatory and sputum smear status in patients with pulmonary tuberculosis (PTB) is crucial for clinical decision making. The purpose of this study was to assess the relationship between gallium-67 (Ga-67) uptake by lung foci and sputum smear status in patients with PTB. We also attempted to predict the patients with acid-fast bacilli (AFB) smear-positive PTB by means of a semiquantitative measurement of Ga-67 uptake ratio using single-photon emission computed tomography images. PATIENTS AND METHODS: Ninety-five patients with PTB were enrolled in this retrospective study. A volume-of-interest method was used to quantify Ga-67 uptake in single-photon emission computed tomography images. The Ga-67 uptake ratio was defined as the maximum voxel value of the pulmonary lesion divided by the maximum voxel value of normal lung tissue. RESULTS: The Ga-67 uptake ratio was higher in patients with active PTB than in those with inactive PTB (3.11 ± 1.52 vs. 1.42 ± 0.14, P<0.01). In active PTB, the Ga-67 uptake ratio was higher in smear-positive patients than in smear-negative patients (3.41 ± 1.60 vs. 2.16 ± 0.61, P<0.01). In patients with AFB smear grades 1+, 2+, and 3+, the Ga-67 uptake ratios were 2.51 ± 0.81, 3.30 ± 1.57, and 4.23 ± 1.73, respectively. The correlation between Ga-67 uptake ratio and AFB smear grading was statistically significant (Spearman's ρ=0.60, P<0.01). In receiver operating characteristic curve analyses, the area under the curve for the Ga-67 uptake ratio was 0.95 ± 0.02 (P<0.01) for predicting active PTB and 0.87 ± 0.04 (P<0.01) for predicting smear-positive active PTB. CONCLUSION: In patients with active PTB, more-intense Ga-67 uptake was associated with more AFB load in the sputum - that is a greater potential to transmit PTB. This finding might facilitate clinical decision making for immediate isolation and treatment to reduce transmission of PTB.