Evaluation of ultra low-dose CT for detection of latent tuberculosis

A CT scan has superior sensitivity for old tuberculosis related lesions
compared to chest radiography in individuals with latent tuberculosis infection
(LTBI), but clinical application of the CT scan in the screening for LTBI is
hampered by a high radiation dose. Recently introduced ultra low-dose CT
(ULDCT) has much improved diagnostic quality compared to chest radiography but
uses a radiation dose comparable to that of a chest radiography.
We hypothesize that ULDCT has better accuracy for LBTI detection than chest
radiography.

Primary Objectives:
1. To determine the proportion of patients with any of various predefined
lesions suggestive of old TB infection detected by ULDCT in patients with LTBI
as defined by TST or IGRA result, but without any LTBI-lesions on CXR
2. To determine which predefined lesions on ULDCT occur at highest frequency in
patients with LTBI.

Secondary Objectives:
1. In patients in whom coincidentally a prior CT has been performed: to compare
the findings on ULDCT with those on CT
2. To assess inter-observer variability for TB related lesions on ULDCT as
compared to CXR.

Prospective, observational study

Ultra low-dose CT examination time itself takes only about 3 seconds. The risks
related to the additional ultra low-dose CT-examination consist of additional
radiation exposure (approximately 0.07 mSv), which is in the same range as that
of a standard chest radiography examination and a factor 50 lower than a
standard chest CT examination. The radiation dose is therefore negligible with
regard to doses acceptable for research purposes with potential clinical
diagnostic gain. The advantages of possible diagnostic outcome of the study,
for example better detection of (calcified) nodules, are expected to exceed the
risks of radiation-induced complications by far.