Contrast-Enhanced T1-Weighted Head and Neck MRI: Prospective Intraindividual Image Quality Comparison of Spiral GRE, Cartesian GRE, and Cartesian TSE Sequences.

BACKGROUND. Sequences with noncartesian k-space sampling may improve image quality of head and neck MRI. OBJECTIVE. The purpose of this study was to compare intraindividually the image quality of a spiral gradient-recalled echo (GRE) sequence and conventional cartesian GRE and cartesian turbo spin-echo (TSE) sequences for contrast-enhanced T1-weighted head and neck MRI. METHODS. This prospective study included patients referred for contrast-enhanced head and neck MRI from August 2020 to May 2021. Patients underwent 1.5-T MRI including contrast-enhanced spiral GRE (2 minutes 28 seconds), cartesian GRE (4 minutes 27 seconds), and cartesian TSE (3 minutes 41 seconds) sequences, acquired in rotating order across patients. Three radiologists independently assessed image quality measures, including conspicuity of prespecified lesions, using 5-point Likert scales. One reader measured maximal extent of dental material artifact and contrast-to-noise ratio (CNR). RESULTS. Thirty-one patients (13 men, 18 women; mean age, 63.8 years) were enrolled. Nineteen patients had a focal lesion; 22 had dental material. Interreader agreement for image quality measures was substantial to excellent (Krippendorff alpha, 0.681-1.000). Scores for overall image quality (whole head and neck, neck only, and head only), pulsation artifact, muscular contour delineation, vessel contour delineation, motion artifact, and differentiation between mucosa and pharyngeal muscles were significantly better for spiral GRE than for cartesian GRE and cartesian TSE for all readers (p < .05). Scores for lesion conspicuity (whole head and neck, neck only, and head only), quality of fat suppression, flow artifact, and foldover artifact were not significantly different between spiral GRE and the cartesian sequences for any reader (p > .05). Dental material artifact scores were significantly worse for spiral GRE than the other sequences for all readers (p < .05). The mean maximum extent of dental material artifact was 39.6 ± 25.5 (SD) mm for spiral GRE, 35.6 ± 24.3 mm for cartesian GRE, and 29.6 ± 21.4 mm for cartesian TSE; the mean CNR was 221.1 ± 94.5 for spiral GRE, 151.8 ± 85.7 for cartesian GRE, and 153.0 ± 63.2 for cartesian TSE (p < .001 between spiral GRE and other sequences for both measures). CONCLUSION. Three-dimensional spiral GRE improves subjective image quality and CNR of head and neck MRI with shorter scan time versus cartesian sequences, though it exhibits larger dental material artifact. CLINICAL IMPACT. A spiral sequence may help overcome certain challenges of conventional cartesian sequences for head and neck MRI.

Single shot zonal oblique multislice SE-EPI diffusion-weighted imaging with low to ultra-high b-values for the differentiation of benign and malignant vertebral spinal fractures.

PURPOSE: To investigate the diagnostic yield of low to ultra-high b-values for the differentiation of benign from malignant vertebral fractures using a state-of-the-art single-shot zonal-oblique-multislice spin-echo echo-planar diffusion-weighted imaging sequence (SShot ZOOM SE-EPI DWI). MATERIALS AND METHODS: 66 patients (34 malignant, 32 benign) were examined on 1.5 T MR scanners. ADC maps were generated from b-values of 0,400; 0,1000 and 0,2000s/mm2. ROIs were placed into the fracture of interest on ADC maps and trace images and into adjacent normal vertebral bodies on trace images. The ADC of fractures and the Signal-Intensity-Ratio (SIR) of fractures relative to normal vertebral bodies on trace images were considered quantitative metrics. The appearance of the fracture of interest was graded qualitatively as iso-, hypo-, or hyperintense relative to normal vertebrae. RESULTS: ADC achieved an area under the curve (AUC) of 0.785/0.698/0.592 for b = 0,400/0,1000/0,2000s/mm2 ADC maps respectively. SIR achieved an AUC of 0.841/0.919/0.917 for b = 400/1000/2000s/mm2 trace images respectively. In qualitative analyses, only b = 2000s/mm2 trace images were diagnostically valuable (sensitivity:1, specificity:0.794). Machine learning models incorporating all qualitative and quantitative metrics achieved an AUC of 0.95/0.98/0.98 for b-values of 400/1000/2000s/mm2 respectively. The model incorporating only qualitative metrics from b = 2000s/mm2 achieved an AUC of 0.97. CONCLUSION: By using quantitative and qualitative metrics from SShot ZOOM SE-EPI DWI, benign and malignant vertebral fractures can be differentiated with high diagnostic accuracy. Importantly qualitative analysis of ultra-high b-value images may suffice for differentiation as well.

Compressed SENSE accelerated 3D T1w black blood turbo spin echo versus 2D T1w turbo spin echo sequence in pituitary magnetic resonance imaging.

PURPOSE: To compare image quality between a 2D T1w turbo spin echo (TSE) sequence and a Compressed SENSE accelerated 3D T1w black blood TSE sequence (equipped with a black blood prepulse for blood signal suppression) in pre- and postcontrast imaging of the pituitary and to assess scan time reductions. METHODS AND MATERIALS: For this retrospective study, 56 patients underwent pituitary MR imaging at 3T. 28 patients were scanned with the 2D- and 28 patients with the accelerated 3D sequence. Two board certified neuroradiologists independently evaluated 13 qualitative image features (12 features on postcontrast- and 1 feature on precontrast images).SNR and CNR measurements were obtained. Interreader agreement was assessed with the intraclass correlation coefficient while differences in scores were assessed with exact Wilcoxon rank sum tests. RESULTS: The interreader agreement ranged from fair (visibility of the ophthalmic nerve, ICC = 0.57) to excellent (presence and severity of pulsation artefacts, ICC = 0.97). The Compressed SENSE accelerated 3D sequence outperformed the 2D sequence in terms of "overall image quality" (median: 4 versus 3, p = 0.04) and "presence and severity of pulsation artefacts" (median: 0 versus 1, p < 0.001). There were no significant differences in any other qualitative and quantitative (SNR, CNR) image quality features. Scan time was reduced by 03:53 min (33.1%) by replacing the 2D with the 3D sequence. CONCLUSION: The Compressed SENSE accelerated 3D T1w black blood TSE sequence is a reliable alternative for the standard 2D sequence in pituitary imaging. The black blood prepulse may aid in suppression of pulsation artefacts.