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[MR tomography of lung metastases with rapid gradient echo sequences. Initial results in diagnostic applications]
1Forschungsschwerpunkt Radiologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum Heidelberg.
Abstract:
Rapid gradient echo sequences enable MR imaging (MRI) of pulmonary metastases with acquisition times of less than 1 s per slice. By optimization of this technique, density, T1- and T2-weighted images can be obtained (FLASH: TR 6.5 ms, TE2 = 3 ms, alpha = 10 degrees; T1w-Turbo-FLASH: TI 200 ms, TR 6.5 ms, TE2 = 3 ms, alpha = 10 degrees; T2w-Turbo-FLASH: TE1 = 50 ms, TR = 6.5 ms, TE2 = 3.5 ms; alpha = 10 degrees). In a prospective study 25 patients in whom pulmonary metastases were suspected were examined with three techniques in all three anatomical planes prior to surgery. All lung metastases revealed a high signal intensity on the FLASH as well as the T2w-Turbo-FLASH images, whereas vascular structures revealed a low signal intensity on the T2-weighted Turbo-FLASH images. Analysis regarding detection and correct number of lung metastases per patient with MRI compared with the histology revealed (n = 25): sensitivity of 82%, specificity 67%, positive predictive value of 95% and negative predictive value of 33%. While MRI does not currently have any diagnostic advantages over CT, the excellent differentiation of parenchymal lesions and vascular structures without the use of contrast medium and the variability of imaging planes are significant methodological advantages.
Insights
Magnetic Resonance Imaging (MRI) can rapidly image pulmonary metastases with fast sequences. While not superior to CT, MRI offers excellent lesion differentiation without contrast media.
Area of Science:
- Medical Imaging
- Radiology
- Pulmonary Medicine
Context:
- Pulmonary metastases detection is crucial for cancer staging.
- Computed Tomography (CT) is the current standard for thoracic imaging.
- Rapid imaging techniques are needed to improve efficiency and patient comfort.
Purpose:
- To evaluate the efficacy of rapid gradient echo sequences in Magnetic Resonance Imaging (MRI) for detecting pulmonary metastases.
- To compare MRI performance against histology in a prospective patient cohort.
- To assess the diagnostic advantages and limitations of optimized MRI sequences.
Summary:
- Fast gradient echo sequences (FLASH, T1w-Turbo-FLASH, T2w-Turbo-FLASH) enabled MR imaging of pulmonary metastases with sub-second acquisition times per slice.
- In 25 patients, MRI demonstrated high signal intensity for lung metastases on FLASH and T2w-Turbo-FLASH images, with low signal for vascular structures on T2w-Turbo-FLASH.
- MRI achieved 82% sensitivity and 67% specificity in detecting pulmonary metastases compared to histology.
Impact:
- Optimized MRI sequences provide excellent differentiation of lung lesions and vascular structures without contrast agents.
- The ability to image in multiple anatomical planes is a significant methodological advantage of MRI.
- While not currently surpassing CT, MRI shows promise for pulmonary metastasis detection with further development.