Small low-risk pulmonary nodules on chest digital radiography: can we predict whether the nodule is benign?

AIM: To evaluate digital chest radiography (CR) performance compared to computed tomography (CT) for characterising small low-risk pulmonary nodules detected incidentally in non-oncological patients. A second aim was to assess the prevalence of calcification and possible false-positive findings mimicking nodules. MATERIALS AND METHODS: Two hundred and seven patients who presented with a pulmonary nodule on CR and underwent CT were included prospectively. Nine radiologists blinded to the CT images reviewed the CRs assessing for the presence of nodules. Afterwards, the same radiologists evaluated the corresponding CT for the presence of nodules, dimensions, and calcification. If the nodule was not present on CT, it was considered a false-positive finding, and possible confounding factors on CR were investigated. RESULTS: Among all 213 nodules seen on CR, 32.4% were revealed to be false-positive findings on CT, mostly due to images formed by vessels (53.6%), osseous aetiologies (30.4%), and skin lesions (13%). Most nodules <6 mm detected on radiographies had benign calcification on CT (n=90; 67.7%). Comparatively, only 41.2% of nodules ≥6 mm on the CR had benign calcification. Among all nodules <6 mm detected on CR, 95.5% were calcified or not present at CT against 81.2% for those ≥6 mm (p<0.001). CONCLUSION: The present study demonstrated that 95.5% of pulmonary nodules smaller than 6 mm on CRs are either calcified (benign) or represent a false-positive finding on CT. These results suggest that nodule measures on CR smaller than 6 mm most likely represent a benign finding.

Morphological characteristics of the reversed halo sign that may strongly suggest pulmonary infarction.

AIM: To analyse the morphological characteristics of the reversed halo sign (RHS) on unenhanced chest computed tomography (CT), which raise suspicion of pulmonary infarction (PI) associated with pulmonary embolism (PE), and to compare these characteristics with those observed in the RHS caused by other diseases. MATERIAL AND METHODS: CT images of 145 patients (250 RHSs) were reviewed retrospectively. Sixty-four patients had the RHS due to PI; in 81 immunocompetent patients, the RHS was caused by alternative pulmonary diseases. All PIs secondary to PE were confirmed at CT angiography. Other diagnoses were confirmed using published criteria. Two independent thoracic radiologists, who were blinded patient demographics, clinical data, and final diagnoses, analysed the morphological CT features of the RHSs. RESULTS: Seventy-four RHSs were found in the PI group and 176 RHSs in the group of other diseases. Single RHSs were associated more frequently with PI compared with the group without PIs; three or more lesions were seen only in patients with other diseases. Low-attenuation areas inside the RHS, with or without reticulation, were observed in 94.59% of PI-associated lesions, and in no patient in the group without PI (p<0.001). Subpleural involvement (p<0.001) and lower-lung predominance (p=0.001) were also associated more frequently with PI. Pleural effusion was observed in 64.06% of patients with PI and in only 6.17% of those with other diseases (p<0.001). CONCLUSIONS: A single RHS with low-attenuation areas inside the halo, with or without reticulation, is highly suggestive of PI. Lower-lung predominance and pleural effusion also suggest PI.

High-resolution CT findings of pulmonary tuberculosis in liver transplant patients.

AIM: To assess the high-resolution computed tomography (HRCT) findings in liver transplant patients diagnosed with pulmonary Mycobacterium tuberculosis infection. MATERIALS AND METHODS: The HRCT findings from 19 patients diagnosed with pulmonary tuberculosis infection after liver transplantation were reviewed. The patients included were 12 men and seven women, age range 23-65 years; mean age 57 years. The diagnosis was established with Mycobacterium tuberculosis detection in bronchoalveolar lavage, sputum, or biopsy. HRCT images were reviewed independently by two observers who reached a consensus decision. The HRCT findings were classified as (1) miliary nodules; (2) cavitation and centrilobular tree-in-bud nodules; (3) ground-glass attenuation and consolidation; and (4) mediastinal lymph node enlargement. RESULTS: The time between the transplantation and the diagnosis of pulmonary tuberculosis ranged from 7 to 153 days with an average of 79 days. The main HRCT pattern was cavitation and centrilobular tree-in-bud nodules (79%) followed by mediastinal lymph node enlargement (10.4%), ground-glass attenuation or consolidation (5.2%) and miliary nodules (5.2%). None of the patients presented pleural effusion. The cavitation and centrilobular tree-in-bud nodules pattern had upper lobe predominance, and ground-glass attenuation and consolidation pattern had middle lobe/lingular segment predominance. CONCLUSION: The main HRCT pattern of pulmonary tuberculosis in liver transplant patients was cavitation and centrilobular tree-in-bud nodules.

Performance of ultra-low-dose CT for the evaluation of coronary calcification: a direct comparison with coronary calcium score.

AIM: To evaluate the diagnostic performance of ultra-low-dose computed tomography (ULDCT) in comparison to standard coronary calcium score (CCS) acquisition for the evaluation of coronary artery calcification (CAC). MATERIALS AND METHODS: Standard CCS acquisition and ULDCT were performed in patients referred for coronary CT angiography for the evaluation of coronary artery disease. CAC in ULDCT was graded subjectively using a four-point scale (from 0, no calcification, to 3, severe calcification) for the complete study and for each individual coronary segment. The summation of all individual coronary segment scores generated an ULDCT total CAC score. ULDCT results were compared to standard Agatston score and sensitivity and specificity of ULDCT were calculated. RESULTS: CCS and ULDCT were performed in 74 patients, with a mean DLP of 77.7 mGy·cm (±12.1) and 9.3 mGy·cm (±0.6), respectively (p<0.001). Coronary calcification was detected in 47 patients (63.5%) in standard CCS acquisition (median Agatston score of 41; interquartile range [IQR]:0263), in comparison to 42 patients (56.8%) in ULDCT (p<0.001). The sensitivity and specificity of the ULDCT total CAC score ≥1 was 80.9% and 85.2%, respectively, with an accuracy of 82.4%. The area under the receiver operating characteristic curve for the presence of CAC was 0.87. CONCLUSION: ULDCT shows good sensitivity, specificity, and overall accuracy for the detection of coronary calcification with a markedly lower radiation dose in comparison to CCS. ULDCT is unlikely to miss coronary calcification in individuals with at least moderate calcium load (Agatston score >100).

Solitary lung cavities: CT findings in malignant and non-malignant disease.

AIM: To assess the computed tomography (CT) findings of solitary cavitary lesions which could potentially aid in differentiating malignant from non-malignant lung disease. MATERIALS AND METHODS: A retrospective study of patients diagnosed with a solitary lung cavity at two university hospitals, who underwent multidetector CT examinations of the chest between 2012 and 2014, was performed. Lesions were evaluated for maximum diameter, maximum wall thickness, and associated findings. Statistical analyses were then conducted and a receiver operating characteristic (ROC) curve was calculated to select the most accurate cut-off value for malignant and non-malignant lesions. RESULTS: CT and clinical records from 96 patients were reviewed. The most frequent aetiologies of non-malignant and malignant lung cavities were mycobacterial infection sequelae (50%, 33/66) and primary lung carcinoma (94%, 28/30), respectively. Significant differences (p<0.05) were found between malignant and non-malignant cases when comparing the averages of maximum wall thickness (15.2 and 7.8 mm, respectively) and maximum diameter of lesions (51 and 35 mm, respectively). The presence of either perilesional consolidation or centrilobular nodules favoured the diagnosis of non-malignant conditions (p<0.05). Maximum wall thicknesses thresholds of ≤7 or ≥24 mm were the most accurate in suggesting non-malignant and malignant aetiologies, respectively. CONCLUSION: Malignant and non-malignant solitary lung cavities differ significantly at CT. Non-malignant lesions tend to exhibit thinner walls, but more perilesional consolidation and centrilobular nodules than malignant lesions. The results reveal that maximum wall thicknesses of ≤7 and ≥24 mm are indicative of non-malignant and malignant disease, respectively.

MRI and CT findings of metastatic pulmonary calcification.

Metastatic pulmonary calcification is a consequence of calcium deposition in the normal pulmonary parenchyma, secondary to abnormal calcium metabolism. The most characteristic radiological manifestation is poorly defined nodular opacities that are mainly seen in the upper lung zone. The aim of this report is to describe the CT and MRI findings observed in two patients with metastatic pulmonary calcification. The disease may present in CT as consolidations with calcification, and with a high lesion/muscle signal intensity ratio on T(1) weighted imaging without contrast in MRI. The high signal on T(1) weighted imaging probably occurs because the low calcium concentration of the lesion changes the surface effects of diamagnetic calcium particles, causing T(1) shortening of water protons. MRI is a good option for characterising calcium accumulation caused by a metabolic disorder.

Valsalva manoeuvre effect on distribution of lung damage in heroin inhalation.

This article reports the case of a patient demonstrating acute bilateral pneumonitis almost completely confined to the upper lobes as a result of inhaling heroin. We attribute this distribution to the patient performing the Valsalva manoeuvre immediately after inhaling heroin. This pattern has not been reported before and we believe it may be seen more frequently owing to a switch amongst drug users from intravenous to inhaled heroin.

MRI in lung cancer: a pictorial essay.

Imaging studies play a critical role in the diagnosis and staging of lung cancer. CT and 18-fluorodeoxyglucose positron emission tomography CT (PET/CT) are widely and routinely used for staging and assessment of treatment response. Many radiologists still use MRI only for the assessment of superior sulcus tumours, and in cases where invasion of the spinal cord canal is suspected. MRI can detect and stage lung cancer, and this method could be an excellent alternative to CT or PET/CT in the investigation of lung malignancies and other diseases. This pictorial essay discusses the use of MRI in the investigation of lung cancer.