Surgical treatment for endocardial radiofrequency ablation-resistant sustained monomorphic ventricular tachycardia with mural thrombus including dense calcification in the left ventricle

Catheter ablation provides effective results for sustained monomorphic ventricular tachycardia (VT), but the presence of mural thrombus including dense calcification occasionally causes unfavorable outcomes. The case of a 67-year-old man in whom sustained monomorphic VT, which was resistant to endocardial radiofrequency ablation, in the presence of mural thrombus including dense calcification after coronary artery bypass grafting was successfully treated by left ventricular reconstruction with cryoablation is reported.     

Primary orbital neuroblastoma in a 1‐month‐old boy

Neuroblastoma is a malignant tumor predominantly occurring in children and usually arising from the adrenal gland or sympathetic ganglia. We describe a neuroblastoma in a 1‐month‐old boy arising from his left orbital cavity. This tumor was refractory to chemotherapy or radiotherapy, requiring enucleation of the left eye for complete removal of the intraorbital tumor. Thereafter, he received high‐dose chemotherapy followed by autologous peripheral blood stem cell transplantation, and has been in complete remission for 3 years. Unlike neuroblastomas arising from the adrenal gland or sympathetic ganglia, primary orbital neuroblastoma may be refractory even in early infancy.     

Fractional anisotropy and tumor cell density of the tumor core show positive correlation in diffusion tensor magnetic resonance imaging of malignant brain tumors

A noninvasive technique for assessing tumor tissue characteristics is required to assist preoperative surgical planning for malignant brain tumors. Preoperative information on tumor cell density within a tumor would help better define the target for tumor biopsy, resulting in more accurate diagnosis and grading of malignant brain tumors. One possible source of this information is diffusion tensor imaging (DTI), although to date studies have focused on its ability to delineate white matter fiber tracks by fiber-tracking and to detect tumor infiltration around the tumor and normal white matter interface. However, the use of DTI for providing information on cell density has also been examined, although with the controversial results. In addition the exact relationships between cell density and the two key values that DTI provides, namely fractional anisotropy (FA) and mean diffusivity (MD), still need to be investigated. In the present study we performed a retrospective investigation of tumor cell density and FA and MD values in biopsy cases. We found that FA has a good positive correlation (R=0.75) and MD has a good negative correlation (R=0.70) with tumor cell density within the tumor core. Similar correlation was observed between the Ki-67 labeling index and FA (R=0.71) and MD (R=0.62). Thus, measurement of both FA and MD within the tumor core has a potential to provide detailed information on tumor cell density within the tumor. Although data obtained from DTI should be interpreted carefully and comprehensively with other imaging modalities such as positron emission tomography, DTI seems to be informative for planning the best biopsy target containing the highest cell density.     

Denoising using deep-learning-based reconstruction for whole-heart coronary MRA with sub-millimeter isotropic resolution at 3 T: a volunteer study

PURPOSEThe aim of this study was to assess the usefulness of denoising deep-learning-based reconstruction (dDLR) to improve image quality and vessel delineation in noncontrast 3-T whole-heart coronary magnetic resonance angiography (WHCMRA) with sub-millimeter isotropic resolution (Sub-mm) compared with a standard resolution without dDLR (Standard).METHODSFor 10 healthy volunteers, we acquired the WHCMRA with Sub-mm with and without dDLR and Standard to quantify signal- (SNR) and contrast-to-noise ratio (CNR) and vessel edge signal response (VESR) in all the 3 image types. Two independent readers subjectively graded vessel sharpness and signal homogeneity of 8 coronary segments in each patient. We used Kruskal–Wallis test with Bonferroni correction to compare SNR, CNR, VESR, and the subjective evaluation scores among the 3 image types and weighted kappa test to evaluate inter-reader agreement on the scores.RESULTSSNR was significantly higher with Sub-mm with dDLR (P < .001) and Standard (P = .005) than with Sub-mm without dDLR and was comparable between Sub-mm with dDLR and Standard (P = .511). CNR was significantly higher with Sub-mm with dDLR (P < .001) and Standard (P = .005) than with Sub-mm without dDLR and was comparable between Sub-mm with dDLR and Standard (P = .560). VESR was significantly greater with Sub-mm with (P = .001) and without dDLR (P = .017) than with Standard and was comparable between Sub-mm with and without dDLR (P = 1.000). In the proximal, middle, distal, and all the coronary segments, the subjective vessel sharpness was significantly better with Sub-mm with dDLR than Sub-mm without dDLR and Standard (P < .001, for all) and was comparable between Sub-mm without dDLR and Standard (P > .05); the subjective signal homogeneity was significantly improved from Sub-mm without dDLR to Standard to Sub-mm with dDLR (P < .001). The inter-reader agreement was excellent (kappa = 0.84).CONCLUSIONApplication of dDLR is useful for improving image quality and vessel delineation in the WHCMRA with Sub-mm compared with Standard.

Main points

• A denoising method with deep-learning-based reconstruction (dDLR) uses a deep convolution neural network to reduce image noise in magnetic resonance images without additional scan time.
• dDLR can be applied to improve signal- (SNR) and contrast-noise ratio in noncontrast 3-T whole-heart coronary magnetic resonance angiography (WHCMRA) using a spoiled gradient-echo sequence, which offers lower SNR than a steady-state free precession sequence commonly applied at 1.5 T.
• Combined application of dDLR and sub-millimeter isotropic resolution is useful for improving vessel sharpness, signal homogeneity, and delineation of the coronary arteries in the WHCMRA.

Three-dimensional (3D) whole-heart coronary magnetic resonance angiography (WHCMRA) is a noninvasive imaging method for assessing coronary artery stenosis and is advantageous over coronary computed tomography angiography (CCTA) because it does not require radiation exposure or contrast media administration and is only slightly susceptible to calcium-related artifacts.^1-3 Because WHCMRA is commonly limited in delineation of distal coronary segments and quantification of vessel lumen stenosis due to its insufficient spatial resolution and anisotropy, some investigators have used various techniques to acquire WHCMRA with sub-millimeter isotropic resolution (Sub-mm) whose image quality is not necessarily satisfactory at 1.5 T, within an acceptable acquisition time.^4-6 While a steady-state free precession (SSFP) sequence has been commonly applied in noncontrast WHCMRA at 1.5 T, increased B1 field inhomogeneity, frequency offset from tissue susceptibility variation, and specific absorption rate limit consistency of SSFP at 3 T. As such, the spoiled gradient-echo sequence, which decreases the signal-to-noise ratio (SNR) of the coronary arteries, has often been used at 3 T.^7-10A 3-T clinical MR scanner with a maximum gradient magnetic field of 100 mT/m (the slew rate: 200 mT/m/ms) has been recently introduced and can offer thinner slice images at the same bandwidth (i.e., the same sampling interval/time). With this scanner, a denoising method with deep-learning-based reconstruction (dDLR) has been newly developed using a convolution neural network (CNN) to improve SNR in high-resolution MR images without additional scan time.¹¹ Currently, this dDLR algorithm (Advanced intelligent Clear-IQ Engine [AiCE], Canon Medical Systems Corporation) is clinically available only from the single vendor. While some smoothing filters frequently applied in clinical settings are designed to reduce high-frequency noise at the cost of image blurring, we hypothesized that dDLR should only reduce image noise without any negative influence on the delineation of the coronary vessels in WHCMRA. Thus, we performed volunteer studies to assess usefulness of dDLR to improve image quality and coronary vessel delineation in noncontrast WHCMRA with Sub-mm compared with a standard resolution without dDLR (Standard) using this 3-T scanner.     

“Another inchworm sign” on dynamic contrast-enhanced magnetic resonance imaging in pediatric patients with cystitis cystica and glandularis: Radiologic-pathologic correlation

Cystitis cystica and glandularis is a hyperproliferative disease of the urothelium, and may form a papillary or polypoid mass. Clinically, these mass lesions are often difficult to distinguish from malignant tumors. We present a pediatric patient of cystitis cystica and glandularis with a bladder mass and discuss dynamic contrast-enhanced magnetic resonance imaging (MRI) findings and histopathological profiles, which have not been previously explored in the literature. Dynamic contrast-enhanced MRI showed unique, superficial, strong enhancement that resembles an inchworm in appearance. The term “inchworm sign” is a characteristic finding on diffusion-weighted MRI, proposed as a criterion for T-staging in non-muscle-invasive bladder cancer. We would like to propose another “inchworm sign” on dynamic contrast-enhanced MRI as a new hallmark of cystitis cystica and glandularis, which may differentiate it from a malignant tumor.