Automated detection and reacquisition of motion-degraded images in fetal HASTE imaging at 3 T.

PURPOSE: Fetal brain Magnetic Resonance Imaging suffers from unpredictable and unconstrained fetal motion that causes severe image artifacts even with half-Fourier single-shot fast spin echo (HASTE) readouts. This work presents the implementation of a closed-loop pipeline that automatically detects and reacquires HASTE images that were degraded by fetal motion without any human interaction. METHODS: A convolutional neural network that performs automatic image quality assessment (IQA) was run on an external GPU-equipped computer that was connected to the internal network of the MRI scanner. The modified HASTE pulse sequence sent each image to the external computer, where the IQA convolutional neural network evaluated it, and then the IQA score was sent back to the sequence. At the end of the HASTE stack, the IQA scores from all the slices were sorted, and only slices with the lowest scores (corresponding to the slices with worst image quality) were reacquired. RESULTS: The closed-loop HASTE acquisition framework was tested on 10 pregnant mothers, for a total of 73 acquisitions of our modified HASTE sequence. The IQA convolutional neural network, which was successfully employed by our modified sequence in real time, achieved an accuracy of 85.2% and area under the receiver operator characteristic of 0.899. CONCLUSION: The proposed acquisition/reconstruction pipeline was shown to successfully identify and automatically reacquire only the motion degraded fetal brain HASTE slices in the prescribed stack. This minimizes the overall time spent on HASTE acquisitions by avoiding the need to repeat the entire stack if only few slices in the stack are motion-degraded.

Uso de resonancia magnética con secuencia de difusión no-ecoplanar para la detección de colesteatoma en pacientes con cirugía de oído previa: presentación de 4 casos / Use of non-echo-planar diffusion-weighted magnetic resonance imaging for the detection of cholesteatoma in patients with previous ear surgery: presentation of 4 cases

El diagnóstico de colesteatoma es fundamentalmente clínico, pudiendo ser complementado con imágenes. Últimamente, el uso de resonancia magnética con secuencia HASTE ha surgido como herramienta diagnóstica sensible y específica para colesteatoma, permitiendo diferenciar éste del tejido inflamatorio-fibrótico presente en pacientes que han sido sometidos a cirugía de oído previa. En este trabajo se presentan cuatro casos de pacientes con antecedente de cirugía de oído y sospecha de colesteatoma en el mismo oído operado, realizándose RM HASTE y cirugía posterior. Obtuvimos una alta correlación entre la imagen y resultado quirúrgico. Se requiere mayor número de pacientes para determinar la sensibilidad y especificidad en el diagnóstico de colesteatoma en pacientes con cirugía de oídos previa.

The diagnosis of cholesteatoma is mainly established by clinical signs, and can be improved by radiological imaging. Recently, the use of magnetic resonance imaging (MRI) with HASTE sequence has emerged as a sensitive and specific diagnostic tool for cholesteatoma, which allows differentiating it from inflammatory-fibrotic tissue present in patients who have undergone previous surgery ear. Here, we present four cases of patients with a history of ear surgery and a suspected cholesteatoma in the same ear, performing HASTE MRI and subsequent surgery, presenting a high correlation between MRI and surgical outcome. More patients are needed to determine the sensitivity and specificity in the diagnosis of cholesteatoma inpatients with previous ear surgery.

Rapid sequence magnetic resonance imaging in the assessment of children with hydrocephalus.

OBJECTIVE: Recent reports have shown the utility of rapid-acquisition magnetic resonance imaging (MRI) in the evaluation of children with hydrocephalus. Rapid sequence MRI (RS-MRI) acquires clinically useful images in seconds without exposing children to the risks of ionizing radiation or sedation. We review our experience with RS-MRI in children with shunts. METHODS: Overall image quality, cost, catheter visualization, motion artifact, and ventricular size were reviewed for all RS-MRI studies obtained at Seattle Children's Hospital during a 2-year period. Image acquisition time was 12-19 seconds, with sessions usually lasting less than 3 minutes. RESULTS: Image quality was very good or excellent in 94% of studies, whereas only one was graded as poor. Significant motion artifact was noted in 7%, whereas 77% had little or no motion artifact. Catheter visualization was good or excellent in 57%, poor in 36%, and misleading in 7%. Small ventricular size was correlated with poor catheter visualization (Spearman's ρ = 0.586; P < 0.00001). RS-MRI imaging cost ∼$650 more than conventional computed tomography (CT). CONCLUSIONS: Our study supports that RS-MRI is an adequate substitute that allows reduced use of CT imaging and resultant exposure to ionizing radiation. Catheter position visualization remains suboptimal when ventricles are small, but shunt malfunction can be adequately determined in most cases. The cost is significantly more than CT, but the potential for lifetime reduction in radiation exposure may justify this expense in children. Limitations include the risk of valve malfunction after repeated exposure to high magnetic fields and the need for reprogramming with many types of adjustable valves.