Proton MRI in the evaluation of pulmonary sarcoidosis: Comparison to chest CT

Multimodality Imaging for the Diagnosis and Evaluation of Pulmonary Sarcoidosis

Sarcoidosis is a multisystem inflammatory disorder characterized by noncaseating granulomas. The diagnosis of sarcoidosis is based on three criteria: clinical history, consistent imaging findings, and histopathology. Radiologists play an important role for the diagnosis and follow-up evaluation of patients with sarcoidosis, which often require a multimodal approach. This imaging essay will explore the typical and atypical imaging manifestations of sarcoidosis at chest radiography, CT, PET/CT, and MRI, provide imaging examples, and discuss relevant differential diagnoses for clinical practice. Keywords: Thorax, MR-Imaging, Staging, PET/CT, CT, Conventional Radiography, Sarcoidosis, Thoracic Imaging, Scintigraphy Supplemental material is available for this article. © RSNA, 2025.

Comparing three-dimensional zero echo time (3D-ZTE) lung MRI and chest CT in the evaluation of systemic sclerosis-related interstitial lung disease

OBJECTIVE

Systemic sclerosis (SSc) is a chronic disease that can cause interstitial lung disease (ILD), a poor prognostic factor in SSc patients. Given the concerns over radiation exposure from repeated CT scans, there is a growing interest in exploring radiation-free imaging alternatives like MRI for ILD evaluation. The aim of this study is to assess the efficacy of three-dimensional zero echo time (3D-ZTE) MRI in assessing SSc-related ILD compared to the thin-slice chest CT.

METHODS

This prospective single-center study investigated 65 SSc patients. SSc patients underwent CT, 3D-ZTE lung MRI, and pulmonary function tests (PFTs) within a week. Three independent reviews visually quantified ILD extent on ZTE and CT imaging and the correlation of ILD extent with PFTs was analyzed. Statistical analyses were performed, including the intraclass correlation coefficient (ICC), Kruskal-Wallis tests, Bland-Altmann analysis, and correlation analyses between imaging results and PFTs.

RESULTS

ILD was detected in 45 patients via CT. 3D-ZTE MRI identified ILD in 41 (91.1%) of these cases, demonstrating a strong correlation with CT in assessing ILD severity (r = 0.986, p < 0.001). The median ILD extent scores were 5% for CT and 6% for 3D-ZTE MRI. Interobserver reliability for 3D-ZTE MRI was excellent, with ICC values ranging from 0.853 to 0.969. The analysis also revealed significant negative correlations between ILD extent on ZTE MRI and lung function, particularly FVC.

CONCLUSION

3D-ZTE lung MRI is a reliable and radiation-free alternative to chest CT for evaluating SSc-related ILD, with a strong correlation in assessing total fibrosis and ground-glass opacities, though limitations remain in detecting fine reticulations and coarseness.

KEY POINTS

Question Can 3D-ZTE MRI replace thin-slice chest CT as a radiation-free method for assessing SSc-related ILD? Findings 3D-ZTE lung MRI showed an excellent agreement with thin-slice CT in evaluating ILD extent in SSc patients (r = 0.986, p < 0.001). Clinical relevance 3D-ZTE lung MRI provides a reliable, radiation-free alternative to CT for assessing ILD extent in SSc patients, ensuring safer longitudinal monitoring and management.

FDG PET/CT Imaging of Sarcoidosis

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. The diagnostic can be made by histological identification of non-caseous granuloma or by a combination of clinical criteria. Active inflammatory granuloma can lead to fibrotic damage. Although 50% of cases resolve spontaneously, systemic treatments are often necessary to decrease symptoms and avoid permanent organ dysfunction, notably in cardiac sarcoidosis. The course of the disease can be punctuated by exacerbations and relapses and the prognostic depends mainly on affected sites and patient management. FDG-PET/CT along with newer FDG-PET/MR have emerged as key imaging modalities in sarcoidosis, namely for certain diagnostic purposes, staging and biopsy guiding. By identifying with a high sensitivity inflammatory active granuloma, FDG hybrid imaging is a main prognostic tool and therapeutic ally in sarcoidosis. This review aims to highlight the actual critical roles of hybrid PET imaging in sarcoidosis and display a brief perspective for the future which appears to include other radiotracers and artificial intelligence applications.

Imaging evaluation of the pediatric mediastinum: new International Thymic Malignancy Interest Group classification system for children

Mediastinal masses are commonly identified in the pediatric population with cross-sectional imaging central to the diagnosis and management of these lesions. With greater anatomical definition afforded by cross-sectional imaging, classification of mediastinal masses into the traditional anterior, middle and posterior mediastinal compartments - as based on the lateral chest radiograph - has diminishing application. In recent years, the International Thymic Malignancy Interest Group (ITMIG) classification system of mediastinal masses, which is cross-sectionally based, has garnered acceptance by multiple thoracic societies and been applied in adults. Therefore, there is a need for pediatric radiologists to clearly understand the ITMIG classification system and how it applies to the pediatric population. The main purpose of this article is to provide an updated review of common pediatric mediastinal masses and mediastinal manifestations of systemic disease processes in the pediatric population based on the new ITMIG classification system.

Practical protocol for lung magnetic resonance imaging and common clinical indications

Imaging speed, spatial resolution and availability have made CT the favored cross-sectional imaging modality for evaluating various respiratory diseases of children - but only for the price of a radiation exposure. MRI is increasingly being appreciated as an alternative to CT, not only for offering three-dimensional (3-D) imaging without radiation exposure at only slightly inferior spatial resolution, but also for its superior soft-tissue contrast and exclusive morpho-functional imaging capacities beyond the scope of CT. Continuing technical improvements and experience with this so far under-utilized modality contribute to a growing acceptance of MRI for an increasing number of indications, in particular for pediatric patients. This review article provides the reader with practical easy-to-use protocols for common clinical indications in children. This is intended to encourage pediatric radiologists to appreciate the new horizons for applications of this rapidly evolving technique in the field of pediatric respiratory diseases.

Novelties in Imaging of Thoracic Sarcoidosis

Sarcoidosis is a systemic granulomatous disease affecting various organs, and the lungs are the most commonly involved. According to guidelines, diagnosis relies on a consistent clinical picture, histological demonstration of non-caseating granulomas, and exclusion of other diseases with similar histological or clinical picture. Nevertheless, chest imaging plays an important role in both diagnostic assessment, allowing to avoid biopsy in some situations, and prognostic evaluation. Despite the demonstrated lower sensitivity of chest X-ray (CXR) in the evaluation of chest findings compared to high-resolution computed tomography (HRCT), CXR still retains a pivotal role in both diagnostic and prognostic assessment in sarcoidosis. Moreover, despite the huge progress made in the field of radiation dose reduction, chest magnetic resonance (MR), and quantitative imaging, very little research has focused on their application in sarcoidosis. In this review, we aim to describe the latest novelties in diagnostic and prognostic assessment of thoracic sarcoidosis and to identify the fields of research that require investigation.

Magnetic resonance imaging of interstitial lung diseases: A state-of-the-art review

Magnetic resonance imaging (MRI) has been emerging as an imaging modality to assess interstitial lung diseases (ILD). An optimal chest MRI protocol for ILDs should include non-contrast breath-holding sequences, steady-state free-precession sequences, and contrast-enhanced sequences. One of the main MRI applications in ILDs is the differentiation between areas of active inflammation (i.e. reversible stage) and fibrosis. Alveolitis presents high signal intensity on T2-weighted sequences (WS) and early-enhancement on contrast-enhanced MR sequences, while fibrotic-predominant lesions present low signal and late-enhancement in these sequences, respectively. MRI can be useful in connective tissue diseases, idiopathic pulmonary fibrosis, and sarcoidosis. The aim of this state-of-the-art review was to perform a state-of-the-art review on the use of MRI in ILDs, and propose the optimal MRI protocols for imaging ILDs.

MRI evaluation of pulmonary lesions and lung tissue changes induced by tuberculosis

OBJECTIVE

To evaluate the utility of magnetic resonance imaging (MRI) with an advanced motion correction technique in characterizing lung tissue changes and lesions induced by pulmonary tuberculosis (TB).

METHODS

Sixty-three subjects with computed tomography (CT) features of pulmonary TB underwent lung MRI. All subjects with pulmonary TB were confirmed by acid-fast bacillus (AFB) testing or the detection of Mycobacterium tuberculosis. T2-weighted turbo spin echo (TSE) sequence MRI with the MultiVane motion correction technique was used to image the lungs. Routine lung CT images were obtained as reference. MRI and CT images were reviewed by multiple readers independently. The performance of MRI in depicting abnormalities induced by pulmonary TB and their morphological changes were evaluated and compared with the performance of CT.

RESULTS

Lung MRI found pulmonary abnormalities in all 63 TB subjects, with satisfactory quality. With the implementation of MultiVane for T2-weighted TSE sequences to reduce the motion correction effect, MRI showed excellent agreement with CT in detecting abnormal imaging features of pulmonary TB (κ=0.88, p<0.001), such as tree-in-bud sign, ground-glass opacity, consolidation, mass, and cavitation. MRI was advantageous in identifying caseation and liquefactive necrosis based on inhomogeneous signal distribution within consolidations and also in identifying mild pleural effusion. The optimized lung MRI was comparable to CT in detecting non-calcified nodules (κ=0.90), with overall sensitivity of 50.0%, 91.1%, and 100% for nodules of size <5 mm, 5-10 mm, and >10 mm, respectively. However, MRI was less effective in identifying lesions with calcification.

CONCLUSIONS

The clinical implementation of an optimized MRI protocol with the MultiVane motion correction technique for imaging pulmonary TB is feasible. Lung MRI without ionizing radiation is a promising alternative to the clinical standard CT, especially for pregnant women, children, adolescents, and patients requiring short-term and repeated follow-up observations.

Diagnostic Utility of 3T Lung MRI in Children with Interstitial Lung Disease: A Prospective Pilot Study

RATIONALE AND OBJECTIVES

The objective of this study was to assess the diagnostic utility of 3-tesla (3T) magnetic resonance imaging (MRI) of lungs in the detection of interstitial lung disease (ILD) in pediatric patients.

MATERIALS AND METHODS

Twelve children (mean: 8.5 years, range: 4-12 years) with ILD were consecutively enrolled in this prospective study. HRCT and 3T lung MRI were performed in all patients within 2 days of each other. The sensitivity, the specificity, the positive predictive value, and the negative predictive value of detecting lung abnormalities related to ILD with 3T lung MRI were calculated, with high-resolution computed tomography (HRCT) as a standard of reference. Agreement between HRCT and 3T lung MRI, as well as between two reviewers, was calculated with the kappa coefficient.

RESULTS

3T lung MRI had low sensitivity (66.67%) and high specificity (97.33%) in the detection of abnormalities related to ILD when compared to HRCT in children. Although 3T lung MRI performed well in the detection of consolidation, parenchymal bands and fissural thickening with a sensitivity of 100%, the sensitivity of 3T lung MRI in the detection of septal thickening, ground-glass opacity, nodules, and cysts was relatively low (50.0%, 50.0%, 66.67%, and 25.0%, respectively). Substantial agreement was seen between HRCT and 3T lung MRI (k = 0.7), whereas perfect agreement was seen between two reviewers in detecting abnormalities related to pediatric ILD (k = 0.9-1.0).

CONCLUSIONS

In comparison to HRCT, 3T lung MRI with routinely available MRI protocols and sequences can also well detect abnormalities such as consolidation, parenchymal bands, and fissural thickening in children with ILD. However, evaluation of septal thickening, ground-glass opacity, nodules, and cysts is limited with 3T lung MRI.

Dilemma of diagnosing thoracic sarcoidosis in tuberculosis-endemic regions: An imaging-based approach. Part 2

The second part of the review discusses the role of different existing imaging modalities in the evaluation of thoracic sarcoidosis, including chest radiograph, computed tomography, magnetic resonance imaging, endobronchial ultrasound, and positron emission tomography. While summarizing the advantages and pitfalls of each imaging modality, the authors propose imaging recommendations and an algorithm to be followed in the evaluation of clinically suspected case of sarcoidosis in tuberculosis-endemic regions.

Thoracic MRI evaluation of sarcoidosis in children

BACKGROUND

Childhood sarcoidosis is a very rare granulomatous disorder with an unknown etiology. Stage 1 disease is the most common whereas stages 2, 3, and 0 are rare in children.

OBJECTIVE

To evaluate thoracic findings of pediatric pulmonary sarcoidosis on MRI and to compare them with CT findings.

METHODS

Between August 2010 and May 2015, seven consecutive pediatric patients (four male, three female; age range: 8-18 years, mean age: 13.5 ± 3.01 years) who were diagnosed with sarcoidosis were enrolled in our study prospectively. Inclusion criterion was patients with stages 1-4 sarcoidosis who underwent contrast enhanced chest CT for initial diagnosis or follow-up evaluation of thoracic findings and exclusion criteria were patients with stage 0 disease with extra-pulmonary manifestations (n = 4).

RESULTS

Two patients who recovered from stage 2 to stage 0 were interpreted as normal. Five patients had abnormal findings on chest CT, including hilar/mediastinal lymphadenopathy (n = 5, 71%), nodules larger than 3 mm (n = 4, 57%), ground glass opacity (n = 4, 57%), thickening of the pleura/fissure (n = 3, 42%), interlobular septal thickening (n = 2, 28%), atelectasis (n = 1, 14%), consolidation (n = 1, 14%), bronchiectasis (n = 1, 14%), intraparenchymal and subpleural cysts (n = 1,14%), fibrotic bands (n = 1, 14%), and enlarged pulmonary artery (n = 1, 14%). Findings that were detected on CT but not observed by lung MRI were nodules <3 mm (n = 4, 57%), mild bronchiectasis and mild ground glass opacity (n = 1, 14%), and subpleural and intraparenchymal cysts (n = 1, 14%). The sensitivity and specificity of MRI were 85.2% and 100%, respectively. There was no statistically significant difference between lung MRI and CT in detecting the thoracic findings in stages 1, 2, and 4 sarcoidosis (P = 0.1336, 95%Cl).

CONCLUSION

Contrast-enhanced lung MRI with fast imaging sequences is a highly sensitive imaging modality and comparable with CT in evaluating both lung and cardiac abnormalities in pediatric sarcoidosis. Given there is no associated ionizing radiation, chest MRI is a promising imaging modality in this pediatric patient population. Pediatr Pulmonol. 2017;52:494-499. © 2016 Wiley Periodicals, Inc.

Performance of magnetic resonance imaging in pulmonary fungal disease compared to high-resolution computed tomography

To evaluate the performance of magnetic resonance imaging (MRI) compared to computed tomography (CT) in patients diagnosed with pulmonary mycosis. We prospectively included 21 patients diagnosed with pulmonary mycosis between January 2013 and October 2014. Inclusion criteria were presence of respiratory symptoms, histopathological diagnosis of mycosis and absence of mycosis treatment. Reviewers identified one predominant imaging pattern per patient: nodular, reticular or airspace pattern. Afterwards, all CT findings were analysed separately per lobe and compared to MRI. Nodular pattern was the most common found (CT: 76.20%; MRI: 80.96%), followed by airspace pattern (CT and MRI: 9.52%) and reticular (CT: 9.52%; MRI: 4.76%). Compared to CT, MRI performance varied according to radiological finding and pulmonary region. For nodules, MRI presented high sensitivity (100% [95% CI: 93.52-100]) and specificity (100% [95% CI: 92.00-100]). For bronchiectasis and septal thickening, there were poorer positive predictive values (33.33% [95% CI: 1.77-87.47]; and 83.33% [95% CI: 50.88-97.06] respectively). As specificity and negative predictive value had superior results than sensitivity and positive predictive value, rather than for diagnosis of this condition, MRI might be more considered for the follow-up of patients with pulmonary mycosis, an alternative to multiple radiation exposures with CT follow-up.

Rapid lung MRI - paradigm shift in evaluation of febrile neutropenia in children with leukemia: a pilot study

Immunocompromised children with hematological malignancies are at increased risk of developing potentially fatal pulmonary infections. Early detection and prompt treatment is critical to combat morbidity and mortality in these children. Twenty-six children with leukemia (age range: 5-13years) presenting with fever and neutropenia were included in this prospective study, which was approved by the institutional ethics committee. All patients underwent HRCT and MRI of the chest on the same day. The findings of HRCT and MRI were compared, with HRCT as the standard of reference. There was perfect agreement between MRI and CT examinations findings by kappa test (κ = 1). No significant difference was observed between the two modalities by the McNemar test (p > 0.05). Rapid lung MRI is technically feasible; has a high correlation, sensitivity and specificity to CT scan; and can emerge as the first line modality for the detection of pulmonary nodules in children with leukemia and persistent febrile neutropenia.

Proton Magnetic Resonance Imaging for Initial Assessment of Isolated Mycobacterium avium Complex Pneumonia

RATIONALE

Computed tomographic (CT) radiography is the reference standard for imaging Mycobacterium avium complex (MAC) lung infection. Magnetic resonance imaging (MRI) has been shown to be comparable to CT for characterizing other pulmonary inflammatory conditions, but has not been rigorously tested for imaging MAC pneumonia.

OBJECTIVES

To determine the feasibility of pulmonary MRI for imaging MAC pneumonia and to assess the degree of agreement between MRI and CT for assessing the anatomic features and lobar extent of MAC lung infections.

METHODS

Twenty-five subjects with culture-confirmed MAC pneumonia and no identified coinfecting organisms were evaluated by thoracic MRI and then by chest CT imaging performed up to 1 week later. After deidentification, first the MRI and then the CT scans were scored 2 weeks apart by two chest radiologists working independently of one another. Discrepancies were resolved by a third chest radiologist. The scans were scored for bronchiectasis, consolidation or atelectasis, abscess or sacculation, nodules, and mucus plugging using a three-point lobar scale (absent, <50% of lobe, and >50% of lobe). Agreement analyses and ordinary least products regressions were performed.

MEASUREMENTS AND MAIN RESULTS

A fixed bias was found between total CT and MRI scores, with CT scoring higher on average (median difference: 4 on a scale of 48; interquartile range: 3, 6). Fixed biases were found for bronchiectasis and consolidation or atelectasis subscale scores. Both fixed and proportional biases were found between CT and MRI mucus plugging scores. No bias was found between CT and MRI nodule scores. There was nearly perfect lobar percent agreement for more conspicuous findings such as consolidation or atelectasis and abscess or sacculation.

CONCLUSIONS

In this exploratory study of 25 adult patients with culture-proven MAC lung infection, we found moderate agreement between MRI and CT for assessing the anatomic features and lobar extent of disease. Given the feasibility of chest MRI for this condition, future work is warranted to assess the clinical impact of MRI compared with CT in assessing progression of untreated MAC infection and response to treatment over time.

[MRI of interstitial lung diseases: what is possible?]

BACKGROUND

Magnetic resonance imaging (MRI) of the lungs is becoming increasingly appreciated as a third diagnostic imaging modality besides chest x-ray and computed tomography (CT). Its value is well acknowledged for pediatric patients or for scientific use particularly when radiation exposure should be strictly avoided. However, the diagnosis of interstitial lung disease is the biggest challenge of all indications. The objective of this article is a summary of the current state of the art for diagnostic MRI of interstitial lung diseases.

MATERIAL AND METHODS

This article reflects the results of a current search of the literature and discusses them against the background of the authors own experience with lung MRI.

RESULTS

Due to its lower spatial resolution and a higher susceptibility to artefacts MRI does not achieve the sensitivity of CT for the detection of small details for pattern recognition (e.g. fine reticulation and micronodules) but larger details (e.g. coarse fibrosis and honeycombing) can be clearly visualized. Moreover, it could be shown that MRI has the capability to add clinically valuable information on regional lung function (e.g. ventilation, perfusion and mechanical properties) and inflammation with native signal and contrast dynamics.

DISCUSSION

In its present state MRI can be used for comprehensive cardiopulmonary imaging in patients with sarcoidosis or for follow-up of lung fibrosis after initial correlation with CT. Far more indications are expected when the capabilities of MRI for the assessment of regional lung function and activity of inflammation can be transferred into robust protocols for clinical use.

Quiet Submillimeter MR Imaging of the Lung Is Feasible with a PETRA Sequence at 1.5 T

PURPOSE

To assess lung magnetic resonance (MR) imaging with a respiratory-gated pointwise encoding time reduction with radial acquisition (PETRA) sequence at 1.5 T and compare it with imaging with a standard volumetric interpolated breath-hold examination (VIBE) sequence, with extra focus on the visibility of bronchi and the signal intensity of lung parenchyma.

MATERIALS AND METHODS

The study was approved by the local ethics committee, and all subjects gave written informed consent. Twelve healthy volunteers were imaged with PETRA and VIBE sequences. Image quality was evaluated by using visual scoring, numbering of visible bronchi, and quantitative measurement of the apparent contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). For preliminary clinical assessment, three young patients with cystic fibrosis underwent both MR imaging and computed tomography (CT). Comparisons were made by using the Wilcoxon signed-rank test for means and the McNemar test for ratios. Agreement between CT and MR imaging disease scores was assessed by using the κ test.

RESULTS

PETRA imaging was performed with a voxel size of 0.86 mm(3). Overall image quality was good, with little motion artifact. Bronchi were visible consistently up to the fourth generation and in some cases up to the sixth generation. Mean CNR and SNR with PETRA were 32.4% ± 7.6 (standard deviation) and 322.2% ± 37.9, respectively, higher than those with VIBE (P < .001). Good agreement was found between CT and PETRA cystic fibrosis scores (κ = 1.0).

CONCLUSION

PETRA enables silent, free-breathing, isotropic, and submillimeter imaging of the bronchi and lung parenchyma with high CNR and SNR and may be an alternative to CT for patients with cystic fibrosis.