Quantitative analysis of lung and tumour mobility: comparison of two time-resolved MRI sequences

Abstract

The purpose of this study was to describe the use of parallel imaging technique (PAT) using dynamic MRI in lung and tumour mobility during the breathing cycle. 20 patients with stage I non-small cell lung carcinoma were investigated using two dynamic gradient echo sequences with PAT (TrueFISP (fast imaging with steady precession), and fast low angle shot (FLASH). Craniocaudal distance from the apex to the diaphragm of the thorax and tumour mobility during the breathing cycle were measured. Signal-to-noise ratio (SNR) of the tumour was determined. In spite of the different temporal resolutions both trueFISP and FLASH sequence proved to be adequate to continuously measure lung motion and tumour mobility. SNR of the tumour was significantly higher using the trueFISP sequence than FLASH sequence (20.7+/-3.6 vs 5.8+/-2.3, p<0.01). Mobility of the tumour bearing hemithorax was significantly lower compared with the non-tumour bearing hemithorax (p<0.05). Dynamic MRI using PAT allows for continuous quantitative documentation of tumour mobility and lung motion. Because of the higher SNR, trueFISP sequence provides a better delineation of intrapulmonary lesions with a sufficient temporal resolution.

Reproducible Simulation of Respiratory Motion in Porcine Lung Explants

“…A displacement of 2.7 cm at the diaphragmatic dome is consistent with the situation in recumbent human patients at rest, when diaphragmatic breathing predominates [2]. Diaphragm displacement in patients during slow tidal breathing was reported to range between 1.5 and 3 cm [14]. For conceivable therapy studies, this represents the situation that would be expected in patients to be treated e. g. with adaptive radiotherapy.…”

“…Therefore, we did not evaluate lung signal and signal-to-noise ration in detail. Dynamic 2D-MR sequences are already being tested for clinical applications with reasonable signal and detail resolution of the perfused lung [8,14].…”

“…As could be proven the model provides a reasonable precision and validity of breathing motion simulation. Since recent developments have made MRI an interesting tool to study lung motion and function, it is supposed to play a future role in radiation therapy planning [4,6,7,14,22]. Due to its MR-compatibility, the ex-vivo set-up with respiratory motion would allow for comparison of CT and MR data as well.…”

Morphological and functional imaging in COPD with CT and MRI: present and future

“…For data acquisition time resolved techniques with a temporal resolution of 100 ms per frame are used (Figs. 2, 10) [71]. In contrast to normal subjects, patients with emphysema frequently showed reduced, irregular or asynchronous motion of the diaphragm and chest wall, with a significant decrease in the maximum amplitude and the length of apposition of Fig.…”

Imaging tumour motion for radiotherapy planning using MRI

“…The diaphragmatic length was particularly useful in the assessment of respiratory mechanics and the respective effects of pulmonary tumours [12]. In such studies the TrueFISP sequence was superior to a FLASH sequence due to its higher T2 signal [13]. Typical temporal resolution was three images per second.…”