Low-field versus high-field MRI in diagnosing breast disorders

Abstract

We evaluated the performance of low-field MRI in breast disorders by comparing it with high-field MRI and biopsy results. Twenty-eight consecutive patients who were able to undergo two magnetic resonance examinations on following days were examined by high-field and low-field MRI. After T1-weighted sagittal images had been obtained a dynamic 3D axial study was performed followed by the acquisition of contrast-enhanced T1-weighted sagittal images. The images were analyzed separately by two radiologists paying attention to lesion morphology and enhancement kinetics. Six patients had problems in both breasts (34 breasts studied). The results were compared with biopsy results of 27 breasts. There were 16 malignant lesions, two fibroadenomas and nine other benign lesions. The inter-magnetic-resonance-scanner kappa value was 0.77 (substantial agreement), while the interobserver kappa value was 0.86 and 0.81 at low and high field, respectively (excellent agreement). The sensitivity was 100 and 100%, the specificity was 82 and 73% and the accuracy was 93 and 89% at low and high field, respectively. The mean lesion size was 2 cm and the smallest malignant lesion was 8 mm in diameter. Low-field MRI is a promising tool for breast imaging. Larger materials and smaller lesions are needed to evaluate its true sensitivity and specificity.

Contrast-enhanced breast MR imaging of claustrophobic or oversized patients using an open low-field magnet

“…In their study, they evaluated 16 malignant and 11 benign lesions with a mean lesion size of 2 cm and obtained sensitivity, specificity and accuracy values of 100%, 82% and 92%, respectively. Interestingly, the corresponding specificity and accuracy values for the same patients examined using a 1.5-T closed magnet were slightly worse (73% and 89%, respectively), even with an equal 100% sensitivity [15]. However, a relatively high dose (>0.2 mmol/kg) of a conventional contrast agent (gadopentetate dimeglumine) was considered necessary to achieve sufficient enhancement in this study.…”

“…More recently, Pääkkö et al investigated the potential clinical value of low-field breast MR imaging using a dynamic contrast-enhanced MR sequence in conjunction with an open 0.23-T permanent magnet [15]. In their study, they evaluated 16 malignant and 11 benign lesions with a mean lesion size of 2 cm and obtained sensitivity, specificity and accuracy values of 100%, 82% and 92%, respectively.…”

“…Più recentemente, Pääkkö et al [15] hanno investigato il potenziale valore clinico della RM mammaria a contrasto dinamico a basso campo con un magnete aperto permanente operante a 0,23 T [15]. Hanno valutato 16 lesioni maligne e 11 benigne con diametro medio di 2 cm ottenendo una sensibilità del 100%, una specificità dell'82% e un'accuratezza del 92%.…”

“…However, the large majority of these open systems work at low field strength (from 0.2 to 0.5 T). Few studies have evaluated the performance of contrast-enhanced dynamic breast MR on low-field systems, mainly for interventional procedures (MR-guided biopsy and presurgical localisation) [12][13][14][15], and the vast majority of state-of-the-art breast MR studies utilise higher field strength systems primarily because of the greater technical performance (i.e. increased spatial and temporal resolution) achievable [1,16].…”

“…Tuttavia tali sistemi operano per lo più a bassa intensità di campo (da 0,2 a 0,5 T). Un numero limitato di studi ha valutato la performance diagnostica delle indagini RM a contrasto dinamico a basso campo, per lo più a fini interventistici (biopsie e centraggi RM-guidati) [12][13][14][15], e la stragrande maggioranza degli studi di RM mammaria allo stato dell'arte sono realizzati con campi magnetici più elevati che consentono migliori performance tecniche (superiore risoluzione spaziale e temporale) [1,16]. Occorre inoltre considerare che tutti gli studi a basso campo sono stati condotti con gli usuali mezzi di contrasto caratterizzati da relassività r1 nell'intervallo tra 3,7 e 4,6 l mmol -1 s -1 (misurate a 1,5 T) [17,18].…”