Evaluation of Malignant Breast Lesions Using High-resolution Readout-segmented Diffusion-weighted Echo-planar Imaging: Comparison with Pathology

Purpose:We aimed to investigate the performance of high resolution-diffusion-weighted imaging (HR-DWI) using readout-segmented echo-planar imaging in visualizing malignant breast lesions and evaluating their extent, using pathology as a reference.Methods:This retrospective study included patients who underwent HR-DWI with surgically confirmed malignant breast lesions. Two radiologists blinded to the final diagnosis evaluated HR-DWI independently and identified the lesions, measuring their maximum diameters. Another radiologist confirmed if those lesions were identical to the pathology. The maximum diameters of the lesions between HR-DWI and pathology were compared, and their correlations were calculated using Spearman’s correlation coefficient. Apparent diffusion coefficient (ADC) values of the lesions were measured.Results:Ninety-five mass/64 non-mass lesions were pathologically confirmed in 104 females. Both radiologists detected the same 93 mass lesions (97.9%). Spearman’s correlation coefficient for mass lesions were 0.89 and 0.90 (P < 0.0001 and 0001) for the two radiologists, respectively. The size differences within 10 mm were 90.3% (84/93) and 94.6% (88/93) respectively. One radiologist detected 35 non-mass lesions (54.7%) and another radiologist detected 32 non-mass lesions (50.0%), of which 28 lesions were confirmed as identical. Spearman’s correlation coefficient for non-mass lesions were 0.59 and 0.22 (P = 0.0002 and 0.22), respectively. The mean ADC value of mass lesions and non-mass lesions were 0.80 and 0.89 × 10⁻³ mm²/s, respectively.Conclusion:Using HR-DWI, malignant mass lesions were depicted with excellent agreement with the pathological evaluation. Approximately half of the non-mass lesions could not be identified, suggesting a current limitation of HR-DWI.     

Acoustic radiation force impulse under clinical conditions with single infusion of ultrasound contrast agent evoking arrhythmias in rabbit heart

Journal of Medical Ultrasonics - We previously reported that acoustic radiation force impulse (ARFI) with concomitant administration of perfluorobutane as an ultrasound contrast agent (UCA)-induced...     

Assessing Blood Flow in an Intracranial Stent: A Feasibility Study of MR Angiography Using a Silent Scan after Stent-Assisted Coil Embolization for Anterior Circulation Aneurysms

BACKGROUND AND PURPOSE:Blood flow in an intracranial stent cannot be visualized with 3D time-of-flight MR angiography owing to magnetic susceptibility and radiofrequency shielding. As a novel follow-up tool after stent-assisted coil embolization, we applied MRA by using a Silent Scan algorithm that contains an ultrashort TE combined with an arterial spin-labeling technique (Silent MRA). The purpose of this study was to determine whether Silent MRA could visualize flow in an intracranial stent placed in the anterior circulation.MATERIALS AND METHODS:Nine patients treated with stent-assisted coil embolization for anterior circulation aneurysms underwent MRAs (Silent MRA and TOF MRA) and x-ray digital subtraction angiography. MRAs were performed in the same session on a 3T unit. Two neuroradiologists independently reviewed the MRA images and subjectively scored flow in a stent as 1 (not visible) to 4 (excellent) by referring to the latest x-ray digital subtraction angiography image as a criterion standard.RESULTS:Both observers gave MRA higher scores than TOF MRA for flow in a stent in all cases. The mean score for Silent MRA was 3.44 ± 0.53, and for TOF MRA, it was 1.44 ± 0.46 (P < .001).CONCLUSIONS:Silent MRA was able to visualize flow in an intracranial stent more effectively than TOF MRA. Silent MRA might be useful for follow-up imaging after stent-assisted coil embolization, though these study results may be only preliminary due to some limitations.

Endovascular therapy for intracranial aneurysms has been widely used since the International Subarachnoid Aneurysm Trial.¹ The number of cases of coil embolization for aneurysms is increasing, and the stent-protection technique has widened the applicability to cases that had been otherwise difficult to treat with conventional coil embolization.² Nevertheless, there is a risk of coil compaction or in-stent restenosis after stent-assisted coil embolization. X-ray digital subtraction angiography is the optimal technique used to examine these adverse events, and it is commonly used as a follow-up tool after using an intracranial stent. However, DSA presents some unavoidable risks related to the catheter procedure, radiation, and contrast media.^3–53D time-of-flight MR angiography is widely used for the assessment of cerebral vascular diseases and has also been examined as a noninvasive substitute for DSA.^6–9 These studies generally reported difficulty in visualizing flow in a stent with TOF MRA because of magnetic susceptibility and radiofrequency shielding, though some beneficial aspects were observed in assessing the residual lumen of aneurysms. As a novel follow-up tool after stent-assisted coil embolization, we applied MRA by using a Silent Scan algorithm (GE Healthcare, Milwaukee, Wisconsin) that contains an ultrashort TE combined with an arterial spin-labeling technique (Silent MRA). In this situation, visualizing flow means visualizing arterial geometry and patency. It does not mean directly visualizing blood flow rate. The purpose of this study was to determine whether Silent MRA can visualize flow in an intracranial stent placed at the anterior circulation.