Differences in pulmonary nodular consolidation and pulmonary cavity among drug-sensitive, rifampicin-resistant and multi-drug resistant tuberculosis patients: a computerized tomography study with history length matched cases

Abstract

Background: There have been concerns that literature described radiological feature differences between drug-sensitive pulmonary tuberculosis (DS-PTB) and multidrug-resistant (MDR)-PTB were confounded by that MDR-PTB cases tend to have a longer history. Using history length matched DS-PTB and MDR-PTB cases from a well-defined urban region in Dalian, we retrospectively analysed the CT feature differences of these paired cases with a focus on pulmonary nodular (PN) consolidation and pulmonary cavity (PC).

Methods: There were 33 consecutive MDR-PTB cases [inclusive of rifampicin-resistant (RR) cases, 27 males and 6 females, mean age: 49.2 years], with 19 cases had a history of <1 month and 8 and 6 cases had a history of 1-6 and >6 months respectively. To pair the MDR-PTB cases with history length, matched 33 cases of DS-PTB patients (21 males and 12 females, mean age: 56.5 years) were included. All patients were new PTB without HIV infection. The first CT exams prior to treatment were analysed.

Results: Compared with DS cases, MDR cases had a much higher prevalence of PN (75.76% vs. 45.45%) and a higher number of PN per positive case for PN (6.2 vs.1.53). For the cases >1 month history, MDR-PTB had a higher number of PC per positive case than that of DS-PTB cases (7.18 vs. 2.36). To differentiate DS-PTB from MDR-PTB, receiver operating characteristic (ROC) analysis showed a cutoff PN number of ≥3 had 48.5% sensitivity and 93.9% specificity, and a cutoff PC number of ≥4 had 39.4% sensitivity and 84.9% specificity. The lung field distribution of all lesions tended to be wider for MDR-PTB cases. MDR-PTB cases appeared to be associated with a faster progression in the absence of treatment.

Conclusions: MDR-TB is likely intrinsically more invasive than DS-TB. Multiple PN and Multiple PC are promising signs for the suspicion of MDR-PTB on chest imaging.

Keywords: Differential diagnosis; computed tomography; multidrug-resistant (MDR); pulmonary; tuberculosis (TB).

Figure 1

Illustration of PN and PC. (A,B) Arrow indicates a PN; (C) arrow indicates a cavity with a well-defined wall; (D) arrow indicates a cavity and dotted arrow indicates a PN. *, an aggregation of many small nodules (<6 mm) not counted as PN. (E) Multiple worm-eroding like cavities counted as one cavity, the individual small cavities’ number was not counted in this study. (F) Arrow indicates a cavity and dotted arrow indicates a PN. *, an aggregation of two small nodules (<6 mm) not counted as PN. (G) Arrow indicates a cavity. PN, pulmonary nodular consolidation; PC, pulmonary cavity.

Figure 2

Prevalence (positive rate) and numbers of PN and PC for patients with a history of <1 month, 1–6 months, and >6 months. (A) Number of PN per case; (B) number of PC per case; (C) mean number of PN per case; (D) mean number of PC per case. MDR, multidrug-resistant; DS, drug-sensitive; PC, pulmonary cavity; PN, pulmonary nodular consolidation.

Figure 3

Difference of PN and PC numbers for DS and MDR patients. (A,B) Cases with the largest number of PN or PC are arranged first. (C) Distribution of DS cases (green dots) and MDR (red dots) in a 3-dimensional space with its axis being number of PN, number of PC, and the maximum diameter of PC for each case. A trend of differentiation for DS and MDR cases is noted, but there are also overlaps. MDR, multidrug-resistant; DS, drug-sensitive; PN, pulmonary nodular consolidation; PC, pulmonary cavity.