Accuracy of CT parameters for assessment of tumour size and aggressiveness in lung adenocarcinoma with bronchoalveolar elements.

Accurate determination of tumour size in lung adenocarcinoma with bronchoalveolar features (BAC) is important for the determination of TNM (tumour, nodes, metastasis) scores used in staging, prognosis and therapy response assessment. However, tumour sizes derived using lung window (LW) CT or soft-tissue/mediastinal window (MW) CT often give different results. This study examines which measurement correlates best with actual tumour size and which best identifies advanced disease. This retrospective study included 43 BAC patients who underwent surgical resection with mediastinal lymphadenectomy <4 weeks post CT scan. The largest unidimensional tumour diameter on each CT window was compared with actual histopathological tumour size (HP). LW, MW and HP size measurements and a recently described CT parameter - the modified tumour shadow disappearance rate (mTDR) = (1 - [MW/LW]) - were then used to determine which parameter best discriminated between the presence or absence of advanced disease. There was no difference between HP and LW sizes, but MW significantly underestimated HP size (p<0.0001). Unlike MW (p = 0.01) and mTDR (p = 0.001), neither HP (p = 0.14) nor LW (p = 0.10) distinguished between patients with or without advanced disease. On receiver operating characteristic (ROC) analysis at a cut-off of ≤0.13, the sensitivity and specificity of mTDR for detecting advanced disease were 69% and 89%, respectively. In patients with tumours ≤3 cm, only mTDR remained a significant predictor of advanced disease (p = 0.017), with best cut-off at ≤0.20, giving a sensitivity and specificity of 71% and 94%, respectively. MW better predicts advanced disease than LW and might also need to be recorded for RECIST (response evaluation criteria in solid tumours) assessment for T staging of BAC; however, mTDR appears to be an even better predictor and should also be used.

Efficacy of 99mTc-DTPA lung clearance test in the diagnosis of PCP in HIV-positive patients.

The study aims to evaluate the efficacy of technetium-99m diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) lung clearance test in the diagnosis of pneumocystis carinii pneumonia (PCP) in HIV-positive paediatric patients. Twenty HIV-negative patients with no chest symptoms constituted Group A, 25 HIV antibody positive asymptomatic children formed Group B, while 45 HIV antibody positive children with respiratory infections comprised Group C. Group C was subdivided into C(1) (n = 20, documented PCP on microbiology), C(2) (n = 10, tuberculosis) and C(3) (n = 15, bacterial pneumonias). The mean age group of patients in Group A, Group B and Group C was 4.7 +/- 1.9, 4.2 +/- 1.5 and 4.8 +/- 1.7 years, respectively. All patients were subjected to complete blood count, blood culture, chest radiographs, microscopic staining of sputum (PCP stains, Ziehl-Nielsen staining, Gram staining), ABG and Mantoux test. All these patients underwent dynamic lung scans using (99m)Tc-DTPA aerosols and lung clearance was calculated in terms of half-time transfer value (T(1/2)) value. T(1/2) was compared between different groups and lung scan findings were correlated with radiological and microbiological results. Patients with PCP had T(1/2) in the range of 9.02 +/- 1.35, TB 28.2 +/- 3.03 min and other bacterial pneumonias in the range of 20.5 +/- 3.1 min (range for normal individuals was 49.8 +/- 6.13 min). T(1/2) in patients with PCP was found to be significantly lower when compared with T(1/2) in other groups. Patients with PCP had characteristic biphasic curves while the rest had monophasic curves. Some patients with PCP had low T(1/2) values even when chest radiographs and arterial blood gases were normal. (99m)Tc-DTPA lung clearance test is a sensitive, safe and non-invasive diagnostic tool for the early detection of PCP in HIV-positive paediatric patients.