Combined Compressed Sensing and SENSE to Enhance Radiation Therapy Magnetic Resonance Imaging Simulation.

Purpose: To assess the effect of a combination of compressed sensing and SENSitivity Encoding (SENSE) acceleration techniques on radiation therapy magnetic resonance imaging (MRI) simulation workflows.

Methods And Materials: Thirty-seven acquisitions were performed with both SENSE-only (SENSE) and combined compressed sensing and SENSE (CS) techniques in 24 patients receiving radiation therapy MRI simulation for a wide range of disease sites. The anatomic field of view prescription and image resolution were identical for both SENSE and CS acquisitions to ensure fair comparison.

Clinical experience and workflow challenges with magnetic resonance-only radiation therapy simulation and planning for prostate cancer.

Background And Purpose: Magnetic Resonance (MR)-only planning has been implemented clinically for radiotherapy of prostate cancer. However, fewer studies exist regarding the overall success rate of MR-only workflows. We report on successes and challenges of implementing MR-only workflows for prostate.

Technical Note: A custom-designed flexible MR coil array for spine radiotherapy treatment planning.

Purpose: To assess the performance and optimize the MR image quality when using a custom-built flexible radiofrequency (RF) spine coil array fitted between the immobilization device and the patient for spine radiotherapy treatment planning.

Methods: A 32 channel flexible custom-designed receive-only coil array has been developed for spine radiotherapy simulation for a 3 T Philips MR scanner. Coil signal-to-noise performance and interactions with standard vendor hardware were assessed.

A super-resolution framework for the reconstruction of T2-weighted (T2w) time-resolved (TR) 4DMRI using T1w TR-4DMRI as the guidance.

Purpose: The purpose of this study was to develop T2-weighted (T2w) time-resolved (TR) four-dimensional magnetic resonance imaging (4DMRI) reconstruction technique with higher soft-tissue contrast for multiple breathing cycle motion assessment by building a super-resolution (SR) framework using the T1w TR-4DMRI reconstruction as guidance.

Methods: The multi-breath T1w TR-4DMRI was reconstructed by deforming a high-resolution (HR: 2 × 2 × 2 mm ) volumetric breath-hold (BH, 20s) three-dimensional magnetic resonance imaging (3DMRI) image to a series of low-resolution (LR: 5 × 5 × 5 mm ) 3D cine images at a 2Hz frame rate in free-breathing (FB, 40 s) using an enhanced Demons algorithm, namely [T1 →FB] reconstruction. Within the same imaging session, respiratory-correlated (RC) T2w 4DMRI (2 × 2 × 2 mm ) was acquired based on an internal navigator to gain HR T2w (T2 ) in three states (full exhalation and mid and full inhalation) in ~5 min.

Comparison of Motion-Insensitive T2-Weighted MRI Pulse Sequences for Visualization of the Prostatic Urethra During MR Simulation.

Purpose: The use of magnetic resonance imaging (MRI) for radiation therapy simulation is growing because of its ability to provide excellent delineation of target tissue and organs at risk. With the use of hypofractionated schemes in prostate cancer, urethral sparing is essential; however, visualization of the prostatic urethra can be challenging because of the presence of benign prostatic hyperplasia as well as respiratory motion artifacts. The goal of this study was to compare the utility of 2 motion-insensitive, T2-weighted MRI pulse sequences for urethra visualization in the setting of MRI-based simulation.

Diffusion-weighted MRI of the lung at 3T evaluated using echo-planar-based and single-shot turbo spin-echo-based acquisition techniques for radiotherapy applications.

Purpose: To compare single-shot echo-planar (SS-EPI)-based and turbo spin-echo (SS-TSE)-based diffusion-weighted imaging (DWI) in Non-Small Cell Lung Cancer (NSCLC) patients and to characterize the distributions of apparent diffusion coefficient (ADC) values generated by the two techniques.

Methods: Ten NSCLC patients were enrolled in a prospective IRB-approved study to compare and optimize DWI using EPI and TSE-based techniques for radiotherapy planning. The imaging protocol included axial T2w, EPI-based DWI and TSE-based DWI on a 3 T Philips scanner.

Novel Super-Resolution Approach to Time-Resolved Volumetric 4-Dimensional Magnetic Resonance Imaging With High Spatiotemporal Resolution for Multi-Breathing Cycle Motion Assessment.

Purpose: To develop and evaluate a super-resolution approach to reconstruct time-resolved 4-dimensional magnetic resonance imaging (TR-4DMRI) with a high spatiotemporal resolution for multi-breathing cycle motion assessment.

Methods And Materials: A super-resolution approach was developed to combine fast 3-dimensional (3D) cine MRI with low resolution during free breathing (FB) and high-resolution 3D static MRI during breath hold (BH) using deformable image registration. A T1-weighted, turbo field echo sequence, coronal 3D cine acquisition, partial Fourier approximation, and SENSitivity Encoding parallel acceleration were used.

Multiatlas approach with local registration goodness weighting for MRI-based electron density mapping of head and neck anatomy.

Purpose: The growing use of magnetic resonance imaging (MRI) as a substitute for computed tomography-based treatment planning requires the development of effective algorithms to generate electron density maps for treatment planning and patient setup verification. The purpose of this work was to develop a method to synthesize computerized tomography (CT) for MR-only radiotherapy of head and neck cancer patients.

Methods: The algorithm is based on registration of multiple patient datasets containing both MRI and CT images (a "multiatlas" algorithm).

Direct Comparison of Respiration-Correlated Four-Dimensional Magnetic Resonance Imaging Reconstructed Using Concurrent Internal Navigator and External Bellows.

Purpose: To compare the image quality of amplitude-binned 4-dimensional magnetic resonance imaging (4DMRI) reconstructed using 2 concurrent respiratory (navigator and bellows) waveforms.

Methods And Materials: A prospective, respiratory-correlated 4DMRI scanning program was used to acquire T2-weighted single-breath 4DMRI images with internal navigator and external bellows. After a 10-second training waveform of a surrogate signal, 2-dimensional MRI acquisition was triggered at a level (bin) and anatomic location (slice) until the bin-slice table was completed for 4DMRI reconstruction.

Limited accuracy of DCE-MRI in identification of pathological complete responders after chemoradiotherapy treatment for rectal cancer.

Objectives: To examine whether post-chemoradiotherapy (CRT) DCE-MRI can identify rectal cancer patients with pathologic complete response (pCR).

Methods: From a rectal cancer surgery database 2007-2014, 61 consecutive patients that met the following inclusion criteria were selected for analysis: (1) stage II/III primary rectal adenocarcinoma; (2) received CRT; (3) underwent surgery (4); underwent rectal DCE-MRI on a 1.5-T MRI scanner.

Long-term outcome of magnetic resonance spectroscopic image-directed dose escalation for prostate brachytherapy.

Purpose: To report the long-term control and toxicity outcomes of patients with clinically localized prostate cancer, who underwent low-dose-rate prostate brachytherapy with magnetic resonance spectroscopic image (MRSI)-directed dose escalation to intraprostatic regions.

Methods And Materials: Forty-seven consecutive patients between May 2000 and December 2003 were analyzed retrospectively. Each patient underwent a preprocedural MRSI, and MRS-positive voxels suspicious for malignancy were identified.

Prostate MRSI predicts outcome in radical prostatectomy patients.

Background: New non-invasive methods are needed for sub-stratifying high-risk prostate cancer patients. Magnetic resonance spectroscopic imaging (MRSI) maps metabolites in prostate cancer, providing information on tumor aggressiveness and volume.

Purpose: To investigate the correlation between MRSI and treatment failure (TF) after radical prostatectomy (RP).

High-field small animal magnetic resonance oncology studies.

This review focuses on the applications of high magnetic field magnetic resonance imaging (MRI) and spectroscopy (MRS) to cancer studies in small animals. High-field MRI can provide information about tumor physiology, the microenvironment, metabolism, vascularity and cellularity. Such studies are invaluable for understanding tumor growth and proliferation, response to treatment and drug development.

Anatomic segmentation improves prostate cancer detection with artificial neural networks analysis of 1H magnetic resonance spectroscopic imaging.

Purpose: To assess whether an artificial neural network (ANN) model is a useful tool for automatic detection of cancerous voxels in the prostate from (1)H-MRSI datasets and whether the addition of information about anatomical segmentation improves the detection of cancer.

Materials And Methods: The Institutional Review Board approved this HIPAA-compliant study and waived informed consent. Eighteen men with prostate cancer (median age, 55 years; range, 36-71 years) who underwent endorectal MRI/MRSI before radical prostatectomy were included in this study.

Noninvasive phosphorus magnetic resonance spectroscopic imaging predicts outcome to first-line chemotherapy in newly diagnosed patients with diffuse large B-cell lymphoma.

Rationale And Objectives: Based on their association with malignant proliferation, using noninvasive phosphorus MR spectroscopic imaging ((31)P MRSI), we measured the tumor content of the phospholipid-related phosphomonoesters (PME), phosphoethanolamine and phospholcholine, and its correlation with treatment outcome in newly diagnosed patients with diffuse large B-cell lymphoma (DLBCL) receiving standard first-line chemotherapy.

Experimental Design: The PME value normalized to nucleoside triphosphates (PME/NTP) was measured using (31)P MRSI in tumor masses of 20 patients with DLBCL before receiving standard first-line chemotherapy. Response at 6 months was complete in 13 patients and partial in seven.

Relationships between LDH-A, lactate, and metastases in 4T1 breast tumors.

Purpose: To investigate the relationship between lactate dehydrogenase A (LDH-A) expression, lactate concentration, cell metabolism, and metastases in murine 4T1 breast tumors.

Experimental Design: Inhibition of LDH-A expression and protein levels were achieved in a metastatic breast cancer cell line (4T1) using short hairpin RNA (shRNA) technology. The relationship between tumor LDH-A protein levels and lactate concentration (measured by magnetic resonance spectroscopic imaging, MRSI) and metastases was assessed.

Serial measurement of hepatic lipids during chemotherapy in patients with colorectal cancer: a 1 H MRS study.

Hepatic steatosis is a hallmark of chemotherapy-induced liver injury. We made serial (1) H MRS measurements of hepatic lipids in patients over the time course of a 24-week chemotherapeutic regimen to determine whether (1) H MRS could be used to monitor the progression of chemotherapy-induced steatosis. Thirty-four patients with stage III or IV colorectal cancer receiving 5-fluorouracil, folinic acid and oxaliplatin (n=21) or hepatic arterial infusion of floxuridine with systemic irinotecan (n=13) were studied prospectively.

Performance characteristics of MR imaging in the evaluation of clinically low-risk prostate cancer: a prospective study.

Purpose: To prospectively evaluate diagnostic performance of T2-weighted magnetic resonance (MR) imaging and MR spectroscopic imaging in detecting lesions stratified by pathologic volume and Gleason score in men with clinically determined low-risk prostate cancer.

Materials And Methods: The institutional review board approved this prospective, HIPAA-compliant study. Written informed consent was obtained from 183 men with clinically low-risk prostate cancer (cT1-cT2a, Gleason score≤6 at biopsy, prostate-specific antigen [PSA] level<10 ng/mL [10 μg/L]) undergoing MR imaging before prostatectomy.

Preclinical study of treatment response in HCT-116 cells and xenografts with (1) H-decoupled (31) P MRS.

The topoisomerase I inhibitor, irinotecan, and its active metabolite SN-38 have been shown to induce G(2) /M cell cycle arrest without significant cell death in human colon carcinoma cells (HCT-116). Subsequent treatment of these G(2) /M-arrested cells with the cyclin-dependent kinase inhibitor, flavopiridol, induced these cells to undergo apoptosis. The goal of this study was to develop a noninvasive metabolic biomarker for early tumor response and target inhibition of irinotecan followed by flavopiridol treatment in a longitudinal study.

Preoperative nomograms incorporating magnetic resonance imaging and spectroscopy for prediction of insignificant prostate cancer.

Unlabelled: Study Type--Prognosis (case series). Level of Evidence 4. What's known on the subject? And what does the study add? Nomograms are available that combine clinical and biopsy findings to predict the probability of pathologically insignificant prostate cancer in patients with clinically low-risk disease.

31P MR spectroscopic imaging detects regenerative changes in human liver stimulated by portal vein embolization.

Purpose: First, to evaluate hepatocyte phospholipid metabolism and energetics during liver regeneration stimulated by portal vein embolization (PVE) using proton-decoupled (31)P MR spectroscopic imaging ((31)P-MRSI). Second, to compare the biophysiologic differences between hepatic regeneration stimulated by PVE and by partial hepatectomy (PH).

Materials And Methods: Subjects included six patients with hepatic metastases from colorectal cancer who were scheduled to undergo right PVE before definitive resection of right-sided tumor.

An exploratory study of endorectal magnetic resonance imaging and spectroscopy of the prostate as preoperative predictive biomarkers of biochemical relapse after radical prostatectomy.

Purpose: Radical prostatectomy has significant side effects. Preoperative information predicting its long-term outcome would be valuable to patients and physicians. We determined whether pretreatment endorectal magnetic resonance imaging/magnetic resonance spectroscopic imaging predicts biochemical recurrence after radical prostatectomy.

Prostate tumor volume measurement with combined T2-weighted imaging and diffusion-weighted MR: correlation with pathologic tumor volume.

Purpose: To retrospectively determine the accuracy of diffusion-weighted (DW) magnetic resonance (MR) imaging for identifying cancer in the prostate peripheral zone (PZ) and to assess the accuracy of tumor volume measurements made with T2-weighted imaging and combined T2-weighted and DW MR imaging by using surgical pathologic examination as the reference standard.

Materials And Methods: The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Forty-two patients underwent endorectal MR at 1.

Prediction of prostate cancer recurrence using magnetic resonance imaging and molecular profiles.

Purpose: To evaluate whether pretreatment magnetic resonance imaging (MRI)/MR spectroscopic imaging (MRSI) findings and molecular markers in surgical specimens correlate with each other and with pretreatment clinical variables (biopsy Gleason score, clinical stage, and prostate-specific antigen level) and whether they contribute incremental value in predicting prostate cancer recurrence.

Experimental Design: Eighty-eight prostate cancer patients underwent MRI/MRSI before radical prostatectomy; imaging findings were scored on a scale of 1 to 7 (no tumor seen-lymph node metastasis). Ki-67, phospho-Akt, and androgen receptor expression in surgical specimens were assessed by immunohistochemistry.

Correlation of MR imaging and MR spectroscopic imaging findings with Ki-67, phospho-Akt, and androgen receptor expression in prostate cancer.

Purpose: To retrospectively assess whether magnetic resonance (MR) imaging and MR spectroscopic imaging and selected molecular markers correlate with each other and with clinically insignificant and significant prostate cancer (PCa), as defined at surgical pathologic analysis.

Materials And Methods: The institutional review board approved this HIPAA-compliant study and waived informed consent. Eighty-nine men (mean age, 63 years; range, 46-79 years) with biopsy-proved PCa underwent combined endorectal MR imaging and MR spectroscopic imaging before radical prostatectomy.