Apparent diffusion coefficient measurements in diffusion-weighted magnetic resonance imaging of the anterior mediastinum: inter-observer reproducibility of five different methods of region-of-interest positioning.

OBJECTIVES: To investigate inter-reader reproducibility of five different region-of-interest (ROI) protocols for apparent diffusion coefficient (ADC) measurements in the anterior mediastinum. METHODS: In eighty-one subjects, on ADC mapping, two readers measured the ADC using five methods of ROI positioning that encompassed the entire tissue (whole tissue volume [WTV], three slices observer-defined [TSOD], single-slice [SS]) or the more restricted areas (one small round ROI [OSR]), multiple small round ROI [MSR]). Inter-observer variability was assessed with interclass correlation coefficient (ICC), coefficient of variation (CoV), and Bland-Altman analysis. Nonparametric tests were performed to compare the ADC between ROI methods. The measurement time was recorded and compared between ROI methods. RESULTS: All methods showed excellent inter-reader agreement with best and worst reproducibility in WTV and OSR, respectively (ICC, 0.937/0.874; CoV, 7.3 %/16.8 %; limits of agreement, ±0.44/±0.77 × 10-3 mm2/s). ADC values of OSR and MSR were significantly lower compared to the other methods in both readers (p < 0.001). The SS and OSR methods required less measurement time (14 ± 2 s) compared to the others (p < 0.0001), while the WTV method required the longest measurement time (90 ± 56 and 77 ± 49 s for each reader) (p < 0.0001). CONCLUSIONS: All methods demonstrate excellent inter-observer reproducibility with the best agreement in WTV, although it requires the longest measurement time. KEY POINTS: • All ROI protocols show excellent inter-observer reproducibility. • WTV measurements provide the most reproducible ADC values. • ROI size and positioning influence ADC measurements in the anterior mediastinum. • ADC values of OSR and MSR are significantly lower than other methods. • OSR and WTV methods require the shortest and longest measurement time, respectively.

The imaging spectrum of pulmonary tuberculosis.

Tuberculosis has still an important impact on public health because it is an important cause of death, particularly in developing countries. On the other hand recent studies have shown that tuberculosis is again becoming concentrated in big cities of Western Europe, especially among immigrants, drug addicts, poor people, and the homeless, despite progress in reducing national rates of the disease. Diagnostic imaging is challenging for radiologists because signs of tuberculosis may easily mimic other diseases such as neoplasms or sarcoidosis. Clinical signs and symptoms in affected adults can be non-specific and a high level of pre-test clinical suspicion based on history is fundamental in the diagnostic work-up. Impact of tuberculosis in the world is extremely important considering the high incidence estimated during 2011 that was 8.7 million cases. This article gives a review of imaging patterns of chest tuberculosis as may be detected on conventional radiography and computerized tomography (CT). The main aim is to improve radiologist's familiarity with the spectrum of imaging features of this disease and facilitate timely diagnosis. Furthermore, we consider the emerging role of alternative methods of imaging, such as magnetic resonance imaging (MRI), that can be helpful and highly accurate for a better definition of some signs of tuberculosis.