Fast and ultrafast magnetic resonance imaging in renal lesions

Abstract

Our purpose was to analyze and compare the image quality and contrast-to-noise ratio (CNR) of different fast T1- and T2-weighted sequences with conventional spin-echo sequences in renal MRI. Twenty-three patients with focal renal lesions were examined with a T2-weighted ultrafast turbo spin-echo (UTSE) sequence with and without frequency selective fat suppression (SPIR), a combined gradient-and-spin-echo sequence (GraSE), and a conventional spin-echo sequence (SE). In addition, T1-weighted images were obtained pre- and postcontrast, using a fast spin-echo sequence (TSE) with and without SPIR and the conventional SE sequence. Among the T2-weighted images, the highest CNR and the best image quality were obtained with the UTSE sequence, followed by the fat-suppressed UTSE sequence. GraSE and conventional SE sequences showed a significantly lower CNR and image quality (p < 0.05). The T1-weighted sequences did not show significant differences, in either precontrast or postcontrast measurements. T2-weighted UTSE with and without fat suppression combined excellent image quality and high CNR for imaging and detection of renal lesions. The T1-weighted fast sequences provided no alternative to the gradient-echo or to the conventional SE sequences. The results of this systematic study suggest the use of T2-weighted fast techniques for improved diagnostic accuracy of renal MRI.

Fast sequences with fat suppression in breath-hold mode: new standard in contrast-enhanced T1-weighted MR imaging of renal tumors?

“…The presented UTSE SPIR and SE±EPI sequences with the imaging parameters used in this study seemed to be the best compromise between sufficiently short imaging time and reasonable spatial resolution. The advantages of the T1-weighted sequences with fat suppression in breath-hold mode should be combined with fast T2-weighted sequences [8]. This combination can help to improve diagnostic confidence in renal imaging.…”

“…While in this study no information on motion artifact reduction techniques was given, motion and respiratory artifacts were not mentioned. A recent paper showed that T1-weighted fast and conventional SE sequences with fat suppression showed compromised image quality due to strong motion and respiratory artifacts [8]. In the present study the combination of fat suppression and breath-hold mode of different sequences was investigated.…”

“…All patients received butylscopolaminium bromide (0.1 ml/kg body weight) intravenously to reduce bowel motion. The imaging protocol included recommended T2-weighted sequences described previously [8] and a T1-weighted UTSE sequence before administration of Gd-DTPA. After intravenous administration of contrast agent (0.1 mmol/kg b.w.…”

“…In only one study did an SE sequence with fat suppression provide a sensitivity of 100 % for detection and characterization of solid renal tumors [3], although a respiratory control technique was not described and no analysis of artifacts was performed. In another recently published study T1-weighted SE and TSE sequences had to be used without respiratory control techniques because their application would have reduced T1-weighting and increased scan time by a factor of approximately four [8]. The breathhold technique, on the other hand, offered a significant reduction in respiratory artifacts and phase-encoded noise using a single-breath-hold TSE sequence with SPIR compared with a conventional SE sequence [2]; however, only one kidney was examined at once in this study.…”

Prevalência de artefatos em exames de ressonância magnética do abdome utilizando a seqüência GRASE: comparável com as melhores seqüências rápidas?

“…Neste trabalho, foi encontrado grande predomínio dos artefatos "chemical shift" na seqüência GRASE sobre os outros artefatos estudados, e apenas este demonstrou ser estatisticamente significante (Tabela 1). Este artefato é decorrente de alterações do sinal que resultam das diferenças de freqüência de precessão (freqüência de ressonância) dos prótons de hidrogênio presentes nas moléculas de água e lipídios (Figura 2) (11) . Apesar de freqüente, este artefato não interfere na interpretação das imagens, e em algumas situações clínicas pode até contribuir para esclarecimento diagnóstico (11) .…”