Magnetic resonance imaging of the chest: current and new applications, with an emphasis on pulmonology

Accurate diagnosis of pulmonary inflammatory myofibroblastic tumor by imaging technology before operation: A case report

RATIONALE

Pulmonary inflammatory myofibroblastic tumor (IMT) is a rare borderline tumor, which has the potential of malignant including invasion of surrounding tissues, distant metastasis and recurrence. However, the preoperative diagnosis is difficult and it can also be difficult to distinguish from malignancy in small tissue samples. Preoperative accurate diagnosis has important clinical significance for patients to choose treatment measures and improve the quality of rehabilitation. We was examined by computed tomography (CT) plain scan plus enhanced scan, magnetic resonance diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) imaging technology in an adult female, compared with lung cancer and pulmonary cryptococcus infection for diagnosis of pulmonary IMT.

PATIENT CONCERNS

A 32-year-old female patient was admitted to the hospital "physical examination revealed nodules in the right upper lung for 1 week".

DIAGNOSES

The patient was diagnosed with Pulmonary inflammatory myofibroblastic tumor.

INTERVENTIONS

Single-port thoracoscopic lobectomy was performed after multidisciplinary consultation.

OUTCOMES

DWI and ADC improves the accuracy of preoperative diagnosis and well guides the formulation of treatment measures. The combined CT, DWI, and ADC magnetic resonance imaging technology has more important significance in the diagnosis and differential diagnosis of IMT and lung malignant tumors.

LESSONS

Although accurate preoperative diagnosis of pulmonary IMT is difficult. Chest CT examination combined with DWI and ADC imaging technology has high clinical significance for the diagnosis of IMT.

Novel Magnetic Resonance Imaging for Assessment of Bronchial Stenosis in Lung Transplant Recipients

Bronchial stenosis in lung transplant recipients is a common disorder that adversely affects clinical outcomes. It is evaluated by spirometry, CT scanning, and bronchoscopy with significant limitations. We hypothesize that MRI using both ultrashort echo time (UTE) scans and hyperpolarized (HP) ¹²⁹ Xe gas can offer structural and functional assessment of bronchial stenosis seen after lung transplantation. Six patients with lung transplantation-related bronchial stenosis underwent HP ¹²⁹ Xe MRI and UTE MRI in the same session. Three patients subsequently underwent airway stent placement and had repeated MRI at 4-week follow-up. HP ¹²⁹ Xe MRI depicted decreased ventilation distal to the stenotic airway. After airway stent placement, MRI showed that low-ventilation regions had decreased (35% vs. 27.6%, p = 0.006) and normal-ventilation regions had increased (17.9% vs. 27.6%, p = 0.04) in the stented lung. Improved gas transfer was also seen on ¹²⁹ Xe MRI. There was a good correlation between UTE MRI and independent bronchoscopic airway diameter assessment (Pearson correlation coefficient = 0.92). This pilot study shows that UTE and HP ¹²⁹ Xe MRI are feasible in patients with bronchial stenosis related to lung transplantation and may provide structural and functional airway assessment to guide treatment. These conclusions need to be confirmed with larger studies.

Pulmonary magnetic resonance imaging is similar to chest tomography in detecting inflammation in patients with systemic sclerosis

Interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are prevalent complications of systemic sclerosis (SSc) and are currently the leading causes of death related to the disease. The accurate recognition of these conditions is therefore of utmost importance for patient management. A study was carried out with 24 SSc patients being followed at the Rheumatology Department of the Hospital de Clínicas of Universidade Federal do Paraná (UFPR) and 14 healthy volunteers, with the objective of evaluating the usefulness of lung magnetic resonance imaging (MRI) when assessing ILD in SS patients. The results obtained with lung MRI were compared to those obtained by computed tomography (CT) of the chest, currently considered the examination of choice when investigating ILD in SS patients. The assessed population was predominantly composed of women with a mean age of 50 years, limited cutaneous SS, and a disease duration of approximately 7 years. In most cases, there was agreement between the findings on chest CT and lung MRI. Considering it is a radiation-free examination and capable of accurately identifying areas of lung tissue inflammatory involvement, lung MRI showed to be a useful examination, and further studies are needed to assess whether there is an advantage in using lung MRI instead of chest CT when assessing ILD activity in SS patients.

Chest magnetic resonance imaging: a protocol suggestion

In the recent years, with the development of ultrafast sequences, magnetic resonance imaging (MRI) has been established as a valuable diagnostic modality in body imaging. Because of improvements in speed and image quality, MRI is now ready for routine clinical use also in the study of pulmonary diseases. The main advantage of MRI of the lungs is its unique combination of morphological and functional assessment in a single imaging session. In this article, the authors review most technical aspects and suggest a protocol for performing chest MRI. The authors also describe the three major clinical indications for MRI of the lungs: staging of lung tumors; evaluation of pulmonary vascular diseases; and investigation of pulmonary abnormalities in patients who should not be exposed to radiation.

Magnetic resonance imaging of pulmonary nodules: accuracy in a granulomatous disease-endemic region

OBJECTIVE

To estimate the diagnostic accuracy of signal intensity of the lesion-to-spinal cord ratio (LSR) and apparent diffusion coefficient (ADC) in diffusion-weighted (DW) magnetic resonance imaging of pulmonary nodules suspicious for lung cancer in granulomatous lung disease-endemic regions.

METHODS

Forty-nine patients with indeterminate solitary pulmonary nodules detected by chest computed tomography and histopathologically confirmed diagnoses were included in the study. DW images were analysed semiquantitatively by focusing regions of interest on the lesion and spinal cord at the same level (for LSR calculation). ADCs were estimated from ratios of the two image signal intensities. Ratios of T1 and T2 signal intensity between nodules and muscle were calculated for comparison.

RESULTS

Mean ADCs ± standard deviations for lung cancer and benign lesions were 0.9 ± 0.2 and 1.3 ± 0.2 × 10(-3) mm(2)/s, respectively. Mean LSRs were 1.4 ± 0.3 for lung cancer and 1 ± 0.1 for benign lesions. ADCs and LSRs differed significantly between malignant and benign lesions (P < 0.001). Mean T2 signal intensity ratios also differed significantly between benign and malignant lesions (0.8 ± 0.2 vs. 1.6 ± 0.2; P < 0.05).

CONCLUSIONS

DWI can help to differentiate malignant from benign lesions according to ADC and the LSR with good accuracy.

KEY POINTS

• DW imaging can help differentiate malignant from benign pulmonary nodules. • ADC and LSR signal intensities had only small overlap between malignant and benign pulmonary nodules. • Mean T2 signal intensity ratios differed significantly between benign and malignant lesions.

Magnetic resonance imaging of the chest in the evaluation of cancer patients: state of the art

Magnetic resonance imaging (MRI) has several advantages in the evaluation of cancer patients with thoracic lesions, including involvement of the chest wall, pleura, lungs, mediastinum, esophagus and heart. It is a quite useful tool in the diagnosis, staging, surgical planning, treatment response evaluation and follow-up of these patients. In the present review, the authors contextualize the relevance of MRI in the evaluation of thoracic lesions in cancer patients. Considering that MRI is a widely available method with high contrast and spatial resolution and without the risks associated with the use of ionizing radiation, its use combined with new techniques such as cine-MRI and functional methods such as perfusion- and diffusion-weighted imaging may be useful as an alternative tool with performance comparable or complementary to conventional radiological methods such as radiography, computed tomography and PET/CT imaging in the evaluation of patients with thoracic neoplasias.

Apparent diffusion coefficient values of diffusion-weighted imaging for distinguishing focal pulmonary lesions and characterizing the subtype of lung cancer: a meta-analysis

OBJECTIVES

The potential performance of apparent diffusion coefficient (ADC) values for distinguishing malignant and benign pulmonary lesions, further characterizing the subtype of lung cancer was assessed.

METHODS

PubMed, EMBASE, Cochrane Library, EBSCO, and three Chinese databases were searched to identify eligible studies on diffusion-weighted imaging (DWI) of focal pulmonary lesions. ADC values of malignant and benign lesions were extracted by lesion type and statistically pooled based on a linear mixed model. Further analysis for subtype of lung cancer was also performed. The methodological quality was assessed using the quality assessment of diagnostic accuracy studies tool.

RESULTS

Thirty-four articles involving 2086 patients were included. Malignant pulmonary lesions have significantly lower ADC values than benign lesions [1.21 (95% CI, 1.19-1.22) mm(2)/s vs. 1.76 (95% CI, 1.72-1.80) mm(2)/s; P < 0.05]. There is a significant difference between ADC values of small cell lung cancer and non-small cell lung cancer (P < 0.05), while the differences were not significant among histological subtypes of lung cancer. The methodological quality was relatively high, and the data points from Begg's test indicated that there was probably no obvious publication bias.

CONCLUSIONS

The ADC value is helpful for distinguishing malignant and benign pulmonary lesions and provides a promising method for differentiation of SCLC from NSCLC.

KEY POINTS

• This meta-analysis assesses the role of DWI in pulmonary lesions. • Differentiation and classification subtype of lung cancer is essential for treatment decision-making. • ADC values can help distinguish between malignant and benign lesions. • ADC values might help characterize the subtype of lung cancer.

A systematic review and meta-analysis of the accuracy of diffusion-weighted MRI in the detection of malignant pulmonary nodules and masses

RATIONALE AND OBJECTIVES

To perform a meta-analysis to assess the diagnostic performance of the diffusion-weighted magnetic resonance imaging (DWI) technique in discrimination of benign and malignant pulmonary nodules or masses.

MATERIALS AND METHODS

Data sources were studies published in PubMed, MEDLINE, EMBASE, Cochrane Library, and China National Knowledge Infrastructure databases from January 2001 to May 2013. Studies evaluating the diagnostic accuracy of DWI for benign/malignant discrimination of pulmonary nodules in English or Chinese language were considered for inclusion. Methodological quality was assessed by the quality assessment of diagnostic studies instrument. Sensitivities, specificities, predictive values, diagnostic odds ratios (DORs), and areas under the receiver operating characteristic curve (AUCs) were calculated. Potential threshold effect, heterogeneity, and publication bias were investigated. We also evaluated the clinical utility of DWI in diagnosis of lung lesions.

RESULTS

Seventeen studies comprising 855 malignant and 322 benign lesions were included in this meta-analysis. There was no significant threshold effect. Summary receiver operating characteristic curve showed that AUC was 0.909 (95% confidence interval [CI], 0.862-0.931). Pooled weighted estimates of sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were 0.828 (95% CI, 0.801-0.853), 0.801 (95% CI, 0.753-0.843), 4.01 (95% CI, 2.78-5.80), and 0.20 (95% CI, 0.15-0.27), respectively. Heterogeneity was found to have stemmed primarily from study design (retrospective or prospective study). Subgroup analysis showed that diagnostic performance (sensitivity, 0.88; 95% CI, 0.82-0.92 and specificity, 0.89; 95% CI, 0.79-0.96) of retrospectively designed studies was significantly higher than that of prospectively designed studies. The Deeks' funnel plot indicated the absence of publication bias.

CONCLUSIONS

With respect to the accuracy and DOR, DWI is useful for differentiation between malignant and benign pulmonary nodules or masses. Diagnostic test accuracy is not the be-all and end-all of diagnostic testing. Concerning PLR and NLR, DWI may not help to alter posttest probability compared to pretest probability to sufficiently alter physician's decision making. Future analyses should be conducted in large-scale, high-quality trials to evaluate its clinical value and establish standards of DWI measurement, analysis, and cutoff values of diagnosis.