MRI Gadolinium-Based Contrast Media: Meeting Radiological, Clinical, and Environmental Needs

Gadolinium-based contrast agents (GBCAs) are routinely used in magnetic resonance imaging (MRI). They are essential for choosing the most appropriate medical or surgical strategy for patients with serious pathologies, particularly in oncologic, inflammatory, and cardiovascular diseases. However, GBCAs have been associated with an increased risk of nephrogenic systemic fibrosis in patients with renal failure, as well as the possibility of deposition in the brain, bones, and other organs, even in patients with normal renal function. Research is underway to reduce the quantity of gadolinium injected, without compromising image quality and diagnosis. The next generation of GBCAs will enable a reduction in the gadolinium dose administered. Gadopiclenol is the first of this new generation of GBCAs, with high relaxivity, thus having the potential to reduce the gadolinium dose while maintaining good in vivo stability due to its macrocyclic structure. High-stability and high-relaxivity GBCAs will be one of the solutions for reducing the dose of gadolinium to be administered in clinical practice, while the development of new technologies, including optimization of MRI acquisitions, new contrast mechanisms, and artificial intelligence may help reduce the need for GBCAs. Future solutions may involve a combination of next-generation GBCAs and image-processing techniques to optimize diagnosis and treatment planning while minimizing exposure to gadolinium. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Current best practice for bladder cancer: a narrative review of diagnostics and treatments

This Seminar presents the current best practice for the diagnosis and management of bladder cancer. The scope of this Seminar ranges from current challenges in pathology, such as the evolving histological and molecular classification of disease, to advances in personalised medicine and novel imaging approaches. We discuss the current role of radiotherapy, surgical management of non-muscle-invasive and muscle-invasive disease, highlight the challenges of treatment of metastatic bladder cancer, and discuss the latest developments in systemic therapy. This Seminar is intended to provide physicians with knowledge of current issues in bladder cancer.

A longitudinal study evaluating interim assessment of neoadjuvant chemotherapy for bladder cancer

OBJECTIVES

To evaluate the usefulness of radiological re-staging after two and four cycles of neoadjuvant chemotherapy (NAC), the impact of re-staging on further patient management, and the correlation between clinical and final pathological tumour stage at radical cystectomy (RC).

PATIENTS AND METHODS

We conducted a longitudinal, single-centre, cohort study of prospectively collected consecutive patients who underwent NAC and RC for urothelial muscle-invasive bladder cancer between July 2001 and December 2017. Patients underwent repeated computed tomography scans for re-staging after two cycles of NAC and after completion of NAC before RC.

RESULTS

Of 180 patients, 110 had ≥four cycles of NAC and had complete imaging available. In the entire cohort, further patient management was only changed in 2/180 patients (1.1%) after two cycles of NAC based on radiological findings. Patients who were stable after two cycles but then downstaged after at least four cycles of NAC had a similarly lowered risk of death (hazard ratio [HR] 0.53). Only one patient downstaged after two cycles was subsequently upstaged after four cycles. Clinical downstaging was observed in 51 patients (46%), 55 patients (50%) had no change in clinical stage and four patients (3.6%) were clinically upstaged. Patients clinically downstaged after four cycles of NAC had a lower risk of death (HR 0.49, 95% confidence interval 0.25-0.94; P = 0.033) compared to those with no change or upstaged after completion of NAC.

CONCLUSIONS

Re-staging of muscle-invasive bladder cancer after two cycles of NAC offers little additional information, rarely changes patient management, and may therefore be omitted, whereas re-staging after completion of NAC by CT is a strong predictor of overall survival.

Association Between Multiparametric Magnetic Resonance Imaging of the Prostate and Oncological Outcomes after Primary Treatment for Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT

The diagnostic accuracy of multiparametric magnetic resonance imaging (mpMRI) for prostate cancer (PCa) diagnosis has been extensively explored. Little is known about the prognostic value of mpMRI suspicion scores and other quantitative mpMRI information.

OBJECTIVE

To systematically review the current literature assessing the relationship between pretreatment mpMRI and oncological outcomes after primary treatment for PCa to assess the role of mpMRI as a prognostic tool.

EVIDENCE ACQUISITION

A computerized bibliographic search of MEDLINE/PubMed, EMBASE, Scopus, and the Cochrane Library CENTRAL databases was performed for all studies assessing the relationship between mpMRI and oncological outcomes after primary treatment for PCa. The review protocol is registered in the PROSPERO database (CRD42020209899).

EVIDENCE SYNTHESIS

A total of six studies were included. Reliable evidence is still limited in this field. The Prostate Imaging-Reporting and Data System (PI-RADS) score was an independent predictor of biochemical recurrence (BCR) after radical prostatectomy (RP) in the majority of the studies included. The tumor volume at mpMRI was not significantly associated with BCR after RP for PCa. Data on disease progression and PCa-specific mortality are limited. Heterogeneity among the studies was substantial.

CONCLUSIONS

The review shows that PI-RADS scores provide information on the future likelihood of cancer recurrence or progression, at least for men undergoing RP. We are of the view that this information should be taken into account to identify men at higher risk of unfavorable outcomes.

PATIENT SUMMARY

A higher Prostate Imaging-Reporting and Data System score for magnetic resonance imaging of the prostate seems to be positively associated with oncological failure in prostate cancer and should be incorporated into future risk models.

How to improve image quality of DWI of the prostate-enema or catheter preparation?

OBJECTIVES

To compare the impact of laxative enema preparation versus air/gas suction through a small catheter on image quality of prostate DWI.

METHODS

In this single-center study, 200 consecutive patients (100 in each arm) with either enema or catheter preparation were retrospectively included. Two blinded readers independently assessed aspects of image quality on 5-point Likert scales. Scores were compared between groups and the influence of confounding factors evaluated using multivariable logistic regression. Prostate diameters were compared on DWI and T₂-weighted imaging using intraclass correlation coefficients.

RESULTS

Image quality was significantly higher in the enema group regarding the severity of susceptibility-related artifacts (reader 1: 0.34 ± 0.77 vs. 1.73 ± 1.34, reader 2: 0.38 ± 0.86 vs. 1.76 ± 1.39), the differentiability of the anatomy (reader 1: 3.36 ± 1.05 vs. 2.08 ± 1.31, reader 2: 3.37 ± 1.05 vs. 2.09 ± 1.35), and the overall image quality (reader 1: 3.66 ± 0.77 vs. 2.26 ± 1.33, Reader 2: 3.59 ± 0.87 vs. 2.23 ± 1.38) with almost perfect inter-observer agreement (κ = 0.92-0.95). In the enema group, rectal distention was significantly lower and strongly correlated with the severity of artifacts (reader 1: ρ = 0.79, reader 2: ρ = 0.73). Furthermore, there were significantly fewer substantial image distortions, with odds ratios of 0.051 and 0.084 for the two readers which coincided with a higher agreement of the prostate diameters in the phase-encoding direction (0.96 vs. 0.89).

CONCLUSIONS

Enema preparation is superior to catheter preparation and yields substantial improvements in image quality.

KEY POINTS

• Enema preparation is superior to decompression of the rectum using air/gas suction through a small catheter. • Enema preparation markedly improves the image quality of prostate DWI regarding the severity of susceptibility-related artifacts, the differentiability of the anatomy, and the overall image quality and considerably reduces substantial artifacts that may impair a reliable diagnosis.

Introducing the Node Reporting and Data System 1.0 (Node-RADS): a concept for standardized assessment of lymph nodes in cancer

"Node-RADS" addresses the lack of consensus in the radiologic assessment of lymph node involvement by cancer and meets the increasing demand for structured reporting on the likelihood of disease involvement. Node Reporting and Data System 1.0 (Node-RADS) systematically classifies the degree of suspicion of lymph node involvement based on the synthesis of established imaging findings. Straightforward definitions of imaging findings for two proposed scoring categories "size" and "configuration" are combined into assessment categories between 1 ("very low likelihood") and 5 ("very high likelihood"). This scoring system is suitable for assessing likely involvement of lymph nodes on CT and MRI scans. It can be applied at any anatomical site, and to regional and non-regional lymph nodes in relation to a primary tumor location. Node-RADS will improve communication with referring physicians and promote the consistency of reporting for primary staging and in response assessment settings. KEY POINTS: • Node-RADS standardizes reporting of possible cancer involvement of regional and distant lymph nodes on CT and MRI. • Node-RADS proposes the scoring categories "size" and "configuration" for assigning the 5-point Node-RADS score from 1 ("very low likelihood") to 5 ("very high likelihood"). • Node-RADS aims to increase consensus among radiologists for primary staging and in response assessment settings.

Amide Proton Transfer Weighted Imaging Shows Differences in Multiple Sclerosis Lesions and White Matter Hyperintensities of Presumed Vascular Origin

Objectives: To assess the ability of 3D amide proton transfer weighted (APTw) imaging based on magnetization transfer analysis to discriminate between multiple sclerosis lesions (MSL) and white matter hyperintensities of presumed vascular origin (WMH) and to compare APTw signal intensity of healthy white matter (healthy WM) with APTw signal intensity of MSL and WHM. Materials and Methods: A total of 27 patients (16 female, 11 males, mean age 39.6 years) with multiple sclerosis, 35 patients (17 females, 18 males, mean age 66.6 years) with small vessel disease (SVD) and 20 healthy young volunteers (9 females, 11 males, mean age 29 years) were included in the MSL, the WMH, and the healthy WM group. MSL and WMH were segmented on fluid attenuated inversion recovery (FLAIR) images underlaid onto APTw images. Histogram parameters (mean, median, 10th, 25th, 75th, 90th percentile) were calculated. Mean APTw signal intensity values in healthy WM were defined by "Region of interest" (ROI) measurements. Wilcoxon rank sum tests and receiver operating characteristics (ROC) curve analyses of clustered data were applied. Results: All histogram parameters except the 75 and 90th percentile were significantly different between MSL and WMH (p = 0.018-p = 0.034). MSL presented with higher median values in all parameters. The histogram parameters offered only low diagnostic performance in discriminating between MSL and WMH. The 10th percentile yielded the highest diagnostic performance with an AUC of 0.6245 (95% CI: [0.532, 0.717]). Mean APTw signal intensity values of MSL were significantly higher than mean values of healthy WM (p = 0.005). The mean values of WMH did not differ significantly from the values of healthy WM (p = 0.345). Conclusions: We found significant differences in APTw signal intensity, based on straightforward magnetization transfer analysis, between MSL and WMH and between MSL and healthy WM. Low AUC values from ROC analyses, however, suggest that it may be challenging to determine type of lesion with APTw imaging. More advanced analysis of the APT CEST signal may be helpful for further differentiation of MSL and WMH.

Consensus-based technical recommendations for clinical translation of renal diffusion-weighted MRI

Objectives

Standardization is an important milestone in the validation of DWI-based parameters as imaging biomarkers for renal disease. Here, we propose technical recommendations on three variants of renal DWI, monoexponential DWI, IVIM and DTI, as well as associated MRI biomarkers (ADC, D, D*, f, FA and MD) to aid ongoing international efforts on methodological harmonization.

Materials and methods

Reported DWI biomarkers from 194 prior renal DWI studies were extracted and Pearson correlations between diffusion biomarkers and protocol parameters were computed. Based on the literature review, surveys were designed for the consensus building. Survey data were collected via Delphi consensus process on renal DWI preparation, acquisition, analysis, and reporting. Consensus was defined as ≥ 75% agreement.

Results

Correlations were observed between reported diffusion biomarkers and protocol parameters. Out of 87 survey questions, 57 achieved consensus resolution, while many of the remaining questions were resolved by preference (65–74% agreement). Summary of the literature and survey data as well as recommendations for the preparation, acquisition, processing and reporting of renal DWI were provided.

Discussion

The consensus-based technical recommendations for renal DWI aim to facilitate inter-site harmonization and increase clinical impact of the technique on a larger scale by setting a framework for acquisition protocols for future renal DWI studies. We anticipate an iterative process with continuous updating of the recommendations according to progress in the field.

Electronic supplementary material

The online version of this article (10.1007/s10334-019-00790-y) contains supplementary material, which is available to authorized users.

PI-RADS Steering Committee: The PI-RADS Multiparametric MRI and MRI-directed Biopsy Pathway

High-quality evidence shows that MRI in biopsy-naive men can reduce the number of men who need prostate biopsy and can reduce the number of diagnoses of clinically insignificant cancers that are unlikely to cause harm. In men with prior negative biopsy results who remain under persistent suspicion, MRI improves the detection and localization of life-threatening prostate cancer with greater clinical utility than the current standard of care, systematic transrectal US-guided biopsy. Systematic analyses show that MRI-directed biopsy increases the effectiveness of the prostate cancer diagnosis pathway. The incorporation of MRI-directed pathways into clinical care guidelines in prostate cancer detection has begun. The widespread adoption of the Prostate Imaging Reporting and Data System (PI-RADS) for multiparametric MRI data acquisition, interpretation, and reporting has promoted these changes in practice. The PI-RADS MRI-directed biopsy pathway enables the delivery of key diagnostic benefits to men suspected of having cancer based on clinical suspicion. Herein, the PI-RADS Steering Committee discusses how the MRI pathway should be incorporated into routine clinical practice and the challenges in delivering the positive health impacts needed by men suspected of having clinically significant prostate cancer.

Magnetic resonance imaging biomarkers for chronic kidney disease: a position paper from the European Cooperation in Science and Technology Action PARENCHIMA

Functional renal magnetic resonance imaging (MRI) has seen a number of recent advances, and techniques are now available that can generate quantitative imaging biomarkers with the potential to improve the management of kidney disease. Such biomarkers are sensitive to changes in renal blood flow, tissue perfusion, oxygenation and microstructure (including inflammation and fibrosis), processes that are important in a range of renal diseases including chronic kidney disease. However, several challenges remain to move these techniques towards clinical adoption, from technical validation through biological and clinical validation, to demonstration of cost-effectiveness and regulatory qualification. To address these challenges, the European Cooperation in Science and Technology Action PARENCHIMA was initiated in early 2017. PARENCHIMA is a multidisciplinary pan-European network with an overarching aim of eliminating the main barriers to the broader evaluation, commercial exploitation and clinical use of renal MRI biomarkers. This position paper lays out PARENCHIMA's vision on key clinical questions that MRI must address to become more widely used in patients with kidney disease, first within research settings and ultimately in clinical practice. We then present a series of practical recommendations to accelerate the study and translation of these techniques.

Diffusion-weighted magnetic resonance imaging to assess diffuse renal pathology: a systematic review and statement paper

Diffusion-weighted magnetic resonance imaging (DWI) is a non-invasive method sensitive to local water motion in the tissue. As a tool to probe the microstructure, including the presence and potentially the degree of renal fibrosis, DWI has the potential to become an effective imaging biomarker. The aim of this review is to discuss the current status of renal DWI in diffuse renal diseases. DWI biomarkers can be classified in the following three main categories: (i) the apparent diffusion coefficient-an overall measure of water diffusion and microcirculation in the tissue; (ii) true diffusion, pseudodiffusion and flowing fraction-providing separate information on diffusion and perfusion or tubular flow; and (iii) fractional anisotropy-measuring the microstructural orientation. An overview of human studies applying renal DWI in diffuse pathologies is given, demonstrating not only the feasibility and intra-study reproducibility of DWI but also highlighting the need for standardization of methods, additional validation and qualification. The current and future role of renal DWI in clinical practice is reviewed, emphasizing its potential as a surrogate and monitoring biomarker for interstitial fibrosis in chronic kidney disease, as well as a surrogate biomarker for the inflammation in acute kidney diseases that may impact patient selection for renal biopsy in acute graft rejection. As part of the international COST (European Cooperation in Science and Technology) action PARENCHIMA (Magnetic Resonance Imaging Biomarkers for Chronic Kidney Disease), aimed at eliminating the barriers to the clinical use of functional renal magnetic resonance imaging, this article provides practical recommendations for future design of clinical studies and the use of renal DWI in clinical practice.

Functional and Targeted Lymph Node Imaging in Prostate Cancer: Current Status and Future Challenges

Patients with prostate cancer who have regional lymph node (LN) metastases face an increased risk of death from disease and are therefore treated aggressively. Surgical LN dissection is the established method of staging regional nodes; however, this invasive technique carries substantial morbidities and a noninvasive imaging method is needed to reduce or eliminate the need for extended pelvic LN dissections (ePLND). Conventional computed tomography and magnetic resonance (MR) imaging have proven insensitive and nonspecific because both use nodal size criteria, which is notoriously inaccurate. Novel imaging techniques such as functional MR imaging by using diffusion-weighted MR imaging, MR lymphography with iron oxide particles, and targeted positron emission tomography imaging are currently under development and appear to improve LN staging of prostate cancer. Although progress is being made in staging nodes with imaging, it has not reached the point of replacing ePLND. In this review, the strengths and limitations of these new functional and targeted LN imaging techniques for prostate cancer are discussed. ^© RSNA, 2017.

Functional MRI for the prediction of treatment response in head and neck squamous cell carcinoma: potential and limitations

Pre-treatment or early intra-treatment prediction of patients with head and neck squamous cell carcinomas (HNSCC) who are likely to have tumours that are resistant to chemoradiotherapy (CRT) would enable treatment regimens to be changed at an early time point, or allow patients at risk of residual disease to be targeted for more intensive post-treatment investigation. Research into the potential advantages of using functional-based magnetic resonance imaging (MRI) sequences before or during cancer treatments to predict treatment response has been ongoing for several years. In regard to HNSCC, the reported results from functional MRI research are promising but they have yet to be transferred to the clinical domain. This article will review the functional MRI literature in HNSCC to determine the current status of the research and try to identify areas that are close to application in clinical practice. This review will focus on diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE–MRI) and briefly include proton magnetic resonance spectroscopy (¹H-MRS)and blood oxygen level dependent (BOLD) MRI.

Cross-sectional imaging in cancers of the head and neck: how we review and report

Cancer of the head and neck is the sixth most frequent cancer worldwide and associated with significant morbidity. The head and neck area is complex and divided into various anatomical and functional subunits. Imaging is performed by cross-sectional modalities like computed tomography, magnetic resonance imaging, ultrasound and positron emission tomography-computed tomography, usually with fluorine-18-deoxy-D-glucose. Therefore, knowledge of the cross-sectional anatomy is very important. This article seeks to give an overview of the various cross-sectional imaging modalities used in the evaluation of head and neck cancers. It briefly describes the anatomy of the extracranial head and neck and the role of imaging as well as the imaging appearance of tumours and their extension to lymph nodes, bone and surrounding tissue. The advantages and disadvantages as well as basic requirements of the various modalities are described along with ways of optimizing imaging quality. A general guideline for prescription of the various modalities is given. Pitfalls are many and varied and can be due to anatomical variation, due to pathology which can be misinterpreted and technical due to peculiarities of the various imaging modalities. Knowledge of these pitfalls can help to avoid misinterpretation. The important points to be mentioned while reporting are also enumerated.

Pretherapeutic Staging of Recurrent Laryngeal Carcinoma: Clinical Findings and Imaging Studies Compared with Histopathology

OBJECTIVE: To assess the accuracy of preoperative imaging studies and clinical and endoscopic examinations for recurrent laryngeal carcinoma evaluation.

STUDY DESIGN AND SETTING: A retrospective comparative study was performed at a university department on 42 recurrent laryngeal carcinomas. Surgical specimens were cut into whole-organ slices. Histologic findings were compared with the findings of the different preoperative diagnostic modalities.

RESULTS: The craniocaudal tumor spread was correctly evaluated by endoscopy and imaging studies in 52% and 24%, respectively, and the contralateral tumor spread in 50% and 52%, respectively. The sensitivity, specificity, and accuracy for detection of tumor infiltration of the thyroid was 48%, 88%, and 64% and of the cricoid 47%, 80%, and 67%. The accuracy of recurrent tumor classification (crT) was 50%; most tumors were underclassified.

CONCLUSION: The inadequately evaluated tumor spread and the inadequately classified recurrent tumors were underestimated and underclassified in most cases, respectively.

Radionecrosis or tumor recurrence after radiation of laryngeal and hypopharyngeal carcinomas

OBJECTIVE: To analyze the incidence and diagnostic difficulties of radionecrosis vs tumor recurrence of laryngeal and hypopharyngeal carcinomas.

STUDY DESIGN AND SETTING: Retrospective study on 341 patients treated by radiation alone or radiochemotherapy. The clinicopathologic findings, work-up, treatment, and follow-up of 20 patients with symptoms suggestive but negative for tumor recurrence on initial imaging studies and endoscopy were analyzed.

RESULTS: The incidence of chondroradionecrosis in 341 irradiated patients was 5%. Ten of 20 patients initially negative for tumor recurrence were treated by total laryngectomy; in all laryngectomy specimens, chondroradionecrosis was present, in six specimens associated with tumor recurrence. Ten patients were treated by tracheotomy and tumor recurrence was detected in one patient during follow-up.

CONCLUSION: Chondroradionecrosis is a relatively rare treatment complication. Typical imaging findings suggestive of radionecrosis are often missing. Tumor recurrence may be present beneath an intact mucosa and missed by endoscopy.

Prostate MRI based on PI-RADS version 2: how we review and report

Prostate imaging and interpretation is based on prostate imaging reporting and data system version 2 (PI-RADS™ v2) providing clinical guidelines for multiparametric magnetic resonance imaging (mpMRI) of the prostate. PI-RADS™ v2 aims to promote global standardisation, to diminish variation in the acquisition, interpretation and reporting of prostate mpMRI examinations and to improve detection, localisation, and risk stratification in patients with suspected cancer in treatment naïve prostate glands. It does not address detection of recurrence, progression during active surveillance and evaluation of other parts of the body.

PI-RADS™ v2 improves and standardises communication between radiologists and urologists to detect or exclude the presence of significant prostate cancer with a high likelihood. Findings on mpMRI are assessed on a 5-point category scale based on the probability that a combination of findings on T2-weighted (T2w) sequences, diffusion-weighted MRI (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) correlates with the presence of a clinically significant prostate cancer at a particular location. PI-RADS assessment categories range from 1 to 5 with 5 being most likely to represent clinically significant prostate cancer. The dominant sequence to detect prostate cancer in the peripheral zone is DWI, whereas for tumour detection in the transition zone T2w is the most important sequence. DCE-MRI has been attributed a minor role and only qualitative assessment with presence or absence of focal enhancement is suggested. Up to four suspicious lesions of category 3, 4 and 5 are assigned on a sector map and the index lesion should be identified.

High signal intensity in dentate nucleus and globus pallidus on unenhanced T1-weighted MR images in three patients with impaired renal function and vascular calcification

Gadolinium‐based contrast agents (primarily those with linear chelates) are associated with a dose‐dependent signal hyperintensity in the dentate nucleus and the globus pallidus on unenhanced T1‐weighted MRI following administration to selected patients with normal renal function. The accumulation of gadolinium has also been reported in the skin, heart, liver, lung, and kidney of patients with impaired renal function suffering from nephrogenic systemic fibrosis (NSF). Here we report on three patients with impaired renal function and vascular calcification (two with confirmed NSF) whose unenhanced T1‐weighted MRIs showed conspicuous high signal intensity in the dentate nucleus and the globus pallidus after they had been exposed to relatively low doses of linear gadolinium‐based contrast agents (0.27, 0.45, and 0.68 mmol/kg). Signal ratios between dentate nucleus and pons and between globus pallidus and thalamus were comparable with previously reported measurements in subjects without renal impairment. Of note, all three analysed patients suffered from transient signs of neurological disorders of undetermined cause. In conclusion, the exposure to 0.27‐0.68 mmol/kg of linear gadolinium‐based contrast agent was associated with probable gadolinium accumulation in the brain of three patients suffering from impaired renal function and vascular calcification. © 2016 The Authors. Contrast Media & Molecular Imaging published by John Wiley & Sons Ltd.

Comparison of Intravoxel Incoherent Motion Parameters across MR Imagers and Field Strengths: Evaluation in Upper Abdominal Organs

Purpose To determine the reproducibility of intravoxel incoherent motion (IVIM) parameters measured in upper abdominal organs with magnetic resonance (MR) imagers from different vendors and with different field strengths. Materials and Methods This prospective study was approved by the independent ethics committees of Kanton Bern and Kanton Zurich, and signed informed consent was obtained from all participants. Abdominal diffusion-weighted images in 10 healthy men (mean age, 37 years ± 8 [standard deviation]) were acquired by using 1.5- and 3.0-T MR imagers from three different vendors. Two readers independently delineated regions of interest that were used to measure IVIM parameters (diffusion coefficient [Dt], perfusion fraction [Fp], and pseudodiffusion coefficient [Dp]) in the left and right lobes of the liver, and in the pancreas, spleen, renal cortex, and renal medulla. Measurement reproducibility between readers was assessed with intraclass correlation coefficients (ICCs). Variability across MR imagers was analyzed by using between- and within-subject coefficients of variation (CVs) and analysis of variance (ANOVA). Results Between-reader reproducibility was high for Dt (ICC, 94.6%), intermediate for Fp (ICC, 81.7%), and low for Dp (ICC, 69.5%). Between- and within-subject CVs of Dt were relatively high (>20%) in the left lobe of the liver and relatively low (<10%) in the renal cortex and renal medulla. CVs generally exceeded 15% for Fp values and 20% for Dp. ANOVA indicated significant differences (P < .05) between MR imagers. Conclusion IVIM parameters in the upper abdomen may differ substantially across MR imagers. (©) RSNA, 2015 Online supplemental material is available for this article.

PI-RADS Prostate Imaging - Reporting and Data System: 2015, Version 2

The Prostate Imaging - Reporting and Data System Version 2 (PI-RADS™ v2) is the product of an international collaboration of the American College of Radiology (ACR), European Society of Uroradiology (ESUR), and AdMetech Foundation. It is designed to promote global standardization and diminish variation in the acquisition, interpretation, and reporting of prostate multiparametric magnetic resonance imaging (mpMRI) examination, and it is based on the best available evidence and expert consensus opinion. It establishes minimum acceptable technical parameters for prostate mpMRI, simplifies and standardizes terminology and content of reports, and provides assessment categories that summarize levels of suspicion or risk of clinically significant prostate cancer that can be used to assist selection of patients for biopsies and management. It is intended to be used in routine clinical practice and also to facilitate data collection and outcome monitoring for research.

Impact of the calculation algorithm on biexponential fitting of diffusion-weighted MRI in upper abdominal organs

PURPOSE

To compare the variability, precision, and accuracy of six different algorithms (Levenberg-Marquardt, Trust-Region, Fixed-Dp , Segmented-Unconstrained, Segmented-Constrained, and Bayesian-Probability) for computing intravoxel-incoherent-motion-related parameters in upper abdominal organs.

METHODS

Following the acquisition of abdominal diffusion-weighted magnetic resonance images of 10 healthy men, six distinct algorithms were employed to compute intravoxel-incoherent-motion-related parameters in the left and right liver lobe, pancreas, spleen, renal cortex, and renal medulla. Algorithms were evaluated regarding inter-reader and intersubject variability. Comparability of results was assessed by analyses of variance. The algorithms' precision and accuracy were investigated on simulated data.

RESULTS

A Bayesian-Probability based approach was associated with very low inter-reader variability (average Intraclass Correlation Coefficients: 96.5-99.6%), the lowest inter-subject variability (Coefficients of Variation [CV] for the pure diffusion coefficient Dt : 3.8% in the renal medulla, 6.6% in the renal cortex, 10.4-12.1% in the left and right liver lobe, 15.3% in the spleen, 15.8% in the pancreas; for the perfusion fraction Fp : 15.5% on average; for the pseudodiffusion coefficient Dp : 25.8% on average), and the highest precision and accuracy. Results differed significantly (P < 0.05) across algorithms in all anatomical regions.

CONCLUSION

The Bayesian-Probability algorithm should be preferred when computing intravoxel-incoherent-motion-related parameters in upper abdominal organs.

Metastases in normal-sized pelvic lymph nodes: detection with diffusion-weighted MR imaging

PURPOSE

To prospectively assess the diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging in the detection of pelvic lymph node metastases in patients with prostate and/or bladder cancer staged as N0 with preoperative cross-sectional imaging.

MATERIALS AND METHODS

This study was approved by an independent ethics committee. Written informed consent was obtained from all patients. Patients with no enlarged lymph nodes on preoperative cross-sectional images who were scheduled for radical resection of the primary tumor and extended pelvic lymph node dissection were enrolled. All patients were examined with a 3-T MR unit, and examinations included conventional and DW MR imaging of the entire pelvis. Image analysis was performed by three independent readers blinded to any clinical information. Metastases were diagnosed on the basis of high signal intensity on high b value DW MR images and morphologic features (shape, border). Histopathologic examination served as the standard of reference. Sensitivity and specificity were calculated, and bias-corrected 95% confidence intervals (CIs) were obtained with the bootstrap method. The Fleiss and Cohen κ and median test were applied for statistical analyses.

RESULTS

A total of 4846 lymph nodes were resected in 120 patients. Eighty-eight lymph node metastases were found in 33 of 120 patients (27.5%). Short-axis diameter of these metastases was less than or equal to 3 mm in 68, more than 3 mm to 5 mm in 13, more than 5 mm to 8 mm in five; and more than 8 mm in two. On a per-patient level, the three readers correctly detected metastases in 26 (79%; 95% CI: 64%, 91%), 21 (64%; 95% CI: 45%, 79%), and 25 (76%; 95% CI: 60%, 90%) of the 33 patients with metastases, with respective specificities of 85% (95% CI: 78%, 92%), 79% (95% CI: 70%, 88%), and 84% (95% CI: 76%, 92%). Analyzed according to hemipelvis, lymph node metastases were detected with histopathologic examination in 44 of 240 pelvic sides (18%); the three readers correctly detected these on DW MR images in 26 (59%; 95% CI: 45%, 73%), 19 (43%; 95% CI: 27%, 57%), and 28 (64%; 95% CI: 47%, 78%) of the 44 cases.

CONCLUSION

DW MR imaging enables noninvasive detection of small lymph node metastases in normal-sized nodes in a substantial percentage of patients with prostate and bladder cancer diagnosed as N0 with conventional cross-sectional imaging techniques.

Living renal allograft transplantation: diffusion-weighted MR imaging in longitudinal follow-up of the donated and the remaining kidney

PURPOSE

To determine whether diffusion-weighted (DW) magnetic resonance (MR) imaging in living renal allograft donation allows monitoring of potential changes in the nontransplanted remaining kidney of the donor because of unilateral nephrectomy and changes in the transplanted kidney before and after transplantation in donor and recipient, respectively, and whether DW MR parameters are correlated in the same kidney before and after transplantation.

MATERIALS AND METHODS

The study protocol was approved by the local ethics committee; written informed consent was obtained. Thirteen healthy kidney donors and their corresponding recipients prospectively underwent DW MR imaging (multiple b values) in donors before donation and in donors and recipients at day 8 and months 3 and 12 after donation. Total apparent diffusion coefficient (ADCT) values were determined; contribution of microcirculation was quantified in perfusion fraction (FP). Longitudinal changes of diffusion parameters were compared (repeated-measures one-way analysis of variance with post hoc pairwise comparisons). Correlations were tested (linear regression).

RESULTS

ADCT values in nontransplanted kidney of donors increased from a preexplantation value of (188 ± 9 [standard deviation]) to (202 ± 11) × 10(-5) mm(2)/sec in medulla and from (199 ± 11) to (210 ± 13) × 10(-5) mm(2)/sec in cortex 1 week after donation (P < .004). Medullary, but not cortical, ADCT values stayed increased up to 1 year. ADCT values in allografts in recipients were stable. Compared with values obtained before transplantation in donors, the corticomedullary difference was reduced in allografts (P < .03). Cortical ADCT values correlated with estimated glomerular filtration rate in recipients (R = 0.56, P < .001) but not donors. Cortical ADCT values in the same kidney before transplantation in donors correlated with those in recipients on day 8 after transplantation (R = 0.77, P = .006). FP did not show significant changes.

CONCLUSION

DW MR imaging depicts early adaptations in the remaining nontransplanted kidney of donors after nephrectomy. All diffusion parameters remained constant in allograft recipients after transplantation. This method has potential monitoring utility, although assessment of clinical relevance is needed.

Diffusion-weighted MR imaging of upper abdominal organs: field strength and intervendor variability of apparent diffusion coefficients

PURPOSE

To determine the variability of apparent diffusion coefficient (ADC) values in various anatomic regions in the upper abdomen measured with magnetic resonance (MR) systems from different vendors and with different field strengths.

MATERIALS AND METHODS

Ten healthy men (mean age, 36.6 years ± 7.7 [standard deviation]) gave written informed consent to participate in this prospective ethics committee-approved study. Diffusion-weighted (DW) MR imaging was performed in each subject with 1.5- and 3.0-T MR systems from each of three vendors at two institutions. Two readers independently measured ADC values in seven upper abdominal regions (left and right liver lobe, gallbladder, pancreas, spleen, and renal cortex and medulla). ADC values were tested for interobserver differences, as well as for differences related to field strength and vendor, with repeated-measures analysis of variance; coefficients of variation (CVs) and variance components were calculated.

RESULTS

Interreader agreement was excellent (intraclass coefficient, 0.876). ADC values were (77.5-88.8) ×10(-5) mm(2)/sec in the spleen and (250.6-278.5) ×10(-5) mm(2)/sec in the gallbladder. There were no significant differences between ADC values measured at 1.5 T and those measured at 3.0 T in any anatomic region (P >.10 for all). In two of seven regions at 1.5 T (left and right liver lobes, P < .023) and in four of seven regions at 3.0 T (left liver lobe, pancreas, and renal cortex and medulla, P < .008), intervendor differences were significant. CVs ranged from 7.0% to 27.1% depending on the anatomic location.

CONCLUSION

Despite significant intervendor differences in ADC values of various anatomic regions of the upper abdomen, ADC values of the gallbladder, pancreas, spleen, and kidney may be comparable between MR systems from different vendors and between different field strengths.

Does quantification of USPIO uptake-related signal loss allow differentiation of benign and malignant normal-sized pelvic lymph nodes?

Ultrasmall superparamagnetic iron oxide (USPIO) particles are promising contrast media, especially for molecular and cellular imaging besides lymph node staging owing to their superior NMR efficacy, macrophage uptake and lymphotropic properties. The goal of the present prospective clinical work was to validate quantification of signal decrease on high-resolution T(2)-weighted MR sequences before and 24-36 h after USPIO administration for accurate differentiation between benign and malignant normal-sized pelvic lymph nodes. Fifty-eight patients with bladder or prostate cancer were examined on a 3 T MR unit and their respective lymph node signal intensities (SI), signal-to-noise (SNR) and contrast-to-noise (CNR) were determined on pre- and post-contrast 3D T(2)-weighted turbo spin echo (TSE) images. Based on histology and/or localization, USPIO-uptake-related SI/SNR decrease of benign vs malignant and pelvic vs inguinal lymph nodes was compared. Out of 2182 resected lymph nodes 366 were selected for MRI post-processing. Benign pelvic lymph nodes showed a significantly higher SI/SNR decrease compared with malignant nodes (p < 0.0001). Inguinal lymph nodes in comparison to pelvic lymph nodes presented a reduced SI/SNR decrease (p < 0.0001). CNR did not differ significantly between benign and malignant lymph nodes. The receiver operating curve analysis yielded an area under the curve of 0.96, and the point with optimal accuracy was found at a threshold value of 13.5% SNR decrease. Overlap of SI and SNR changes between benign and malignant lymph nodes were attributed to partial voluming, lipomatosis, histiocytosis or focal lymphoreticular hyperplasia. USPIO-enhanced MRI improves the diagnostic ability of lymph node staging in normal-sized lymph nodes, although some overlap of SI/SNR-changes remained. Quantification of USPIO-dependent SNR decrease will enable the validation of this promising technique with the final goal of improving and individualizing patient care.

Local recurrence after retropubic radical prostatectomy for prostate cancer does not exclusively occur at the anastomotic site

What's known on the subject? and what does the study add?: Local recurrence after radical prostatectomy (RP) for clinically organ-confined prostate cancer is largely assumed to occur at the anastomotic site, as reflected in European and North American guidelines for adjuvant and salvage radiotherapy after RP. However, the exact site of local recurrence often remains undetermined. The present study shows that roughly one out of five patients with local recurrence after RP has histologically confirmed tumour deposits at the resection site of the vas deferens, clearly above the anastomotic site. This should be considered when offering 'blind' radiotherapy to the anastomotic site in patients with biochemical recurrence alone.

OBJECTIVE

To determine the anatomical pattern of local recurrence and the corresponding clinical and pathological variables of patients treated with retropubic radical prostatectomy (RRP).

PATIENTS AND METHODS

In all, 41 patients with biopsy confirmed local recurrence after extended pelvic lymph node dissection and RRP performed between January 1992 and December 2009 at a single tertiary referral academic centre were retrospectively studied. The site of local recurrence as assessed on computed tomography or magnetic resonance imaging was reviewed. Two sites were identified: the vesicourethral anastomotic site and the cranial resection margin of the surgical bed, where the vas deferens was transected and clipped. Age and serum prostate-specific antigen (PSA) level at RRP, pathological tumour and nodal stage, Gleason score, tumour location, surgical margin status, age and serum PSA level at the time of local recurrence, and time to diagnosis of local recurrence were assessed for the two sites and compared with the chi-square or Wilcoxon rank sum tests as appropriate.

RESULTS

Local recurrence occurred at the anastomotic site in 31/41 (76%) patients and at the resection site of the vas deferens in nine of 41 (22%) patients. One patient had distinct lesions at both sites. There was no significant difference in any of the clinical and pathological variables between patients with local recurrence in the former and latter site.

CONCLUSION

Most local recurrences after RRP occur exclusively at the anastomotic site. However, 22% of locally recurrent cases had tumour at the resection site of the vas deferens. This should be taken into account when considering adjuvant or salvage radiation therapy.

Ultrasmall superparamagnetic particles of iron oxide allow for the detection of metastases in normal sized pelvic lymph nodes of patients with bladder and/or prostate cancer

AIM

Lymph node metastases influence prognosis and outcome in patients with bladder and prostate cancer. Cross sectional imaging criteria are limited in detecting metastases in normal sized lymph nodes. This prospective study assessed the diagnostic accuracy of ultrasmall superparamagnetic particles of iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) for the detection of metastases in normal sized lymph nodes using extended pelvic lymph node dissection (ePLND) and histopathology as the reference standard.

METHODS

Seventy-five patients (bladder cancer, n=19, prostate cancer n=48, both, n=8) were examined using 3T MR before and after USPIO-administration. A preoperative reading with two readers in consensus and a second postoperative reading with three independent blinded readers were performed. Results were correlated with histopathology and diagnostic accuracies were calculated for all readings.

RESULTS

A total of 2993 lymph nodes were examined histopathologically. Fifty-four metastatic nodes were found in 20/75 patients (26.7%). The first reading had a sensitivity of 55.0%, specificity of 85.5%, positive predictive value (PPV) of 57.9%, negative predictive value (NPV) of 83.9%, and diagnostic accuracy (DA) of 77.3% on a per patient level. The second reading had a mean sensitivity of 58.3%, specificity of 83.0%, PPV of 58.0%, NPV of 84.4% and DA of 76.4% on a per patient level. The majority of missed metastases were smaller than 5mm in short axis diameter.

CONCLUSIONS

USPIO-enhanced MRI in bladder and prostate cancer patients allows detection of metastases in normal sized lymph nodes and might guide the surgeon to remove suspicious lymph nodes not included in standard PLND.

Therapy response with diffusion MRI: an update

The efficiency of an oncological treatment regimen is often assessed by morphological criteria such as tumour size evaluated by cross-sectional imaging, or by laboratory measurements of plasma biomarkers. Because these types of measures typically allow for assessment of treatment response several weeks or even months after the start of therapy, earlier response assessment that provides insight into tumour function is needed. This is particularly urgent for the evaluation of newer targeted therapies and for fractionated therapies that are delivered over a period of weeks to allow for a change of treatment in non-responding patients. Diffusion-weighted MRI (DW-MRI) is a non-invasive imaging tool that does not involve radiation or contrast media, and is sensitive to tissue microstructure and function on a cellular level. DW-MRI parameters have shown sensitivity to treatment response in a growing number of tumour types and organ sites, with additional potential as predictive parameters for treatment outcome. A brief overview of DW-MRI principles is provided here, followed by a review of recent literature in which DW-MRI has been used to monitor and predict tumour response to various therapeutic regimens.

Diffusion-weighted MR imaging including bi-exponential fitting for the detection of recurrent or residual tumour after (chemo)radiotherapy for laryngeal and hypopharyngeal cancers

OBJECTIVES

To assess whether diffusion-weighted magnetic resonance imaging (DW-MRI) including bi-exponential fitting helps to detect residual/recurrent tumours after (chemo)radiotherapy of laryngeal and hypopharyngeal carcinoma.

METHODS

Forty-six patients with newly-developed/worsening symptoms after (chemo)radiotherapy for laryngeal/hypopharyngeal cancers were prospectively imaged using conventional MRI and axial DW-MRI. Qualitative (visual assessment) and quantitative analysis (mono-exponentially: total apparent diffusion coefficient [ADC(T)], and bi-exponentially: perfusion fraction [F(P)] and true diffusion coefficient [ADC(D)]) were performed. Diffusion parameters of tumour versus post-therapeutic changes were compared, with final diagnosis based on histopathology and follow-up. Mann-Whitney U test was used for statistical analysis.

RESULTS

Qualitative DW-MRI combined with morphological images allowed the detection of tumour with a sensitivity of 94% and specificity 100%. ADC(T) and ADC(D) values were lower in tumour with values 120 ± 49 × 10(-5) mm(2)/s and 113 ± 50 × 10(-5) mm(2)/s, respectively, compared with post-therapeutic changes with values 182 ± 41 × 10(-5) mm(2)/s (P < 0.0002) and 160 ± 47 × 10(-5) mm(2)/s (P < 0.003), respectively. F(P) values were significantly lower in tumours than in non-tumours (13 ± 9% versus 31 ± 16%, P < 0.0002), with F(P) being the best quantitative parameter for differentiation between post-therapeutic changes and recurrence.

CONCLUSIONS

DW-MRI in combination with conventional MRI substantially improves detection and exclusion of tumour in patients with laryngeal and hypopharyngeal cancers after treatment with (chemo)radiotherapy on both qualitative and quantitative analysis, with F(P) being the best quantitative parameter in this context.

Diffusion-weighted MR imaging in the head and neck

Extracranial applications of diffusion-weighted (DW) magnetic resonance (MR) imaging are gaining increasing importance, including in head and neck radiology. The main indications for performing DW imaging in this relatively small but challenging region of the body are tissue characterization, nodal staging, therapy monitoring, and early detection of treatment failure by differentiating recurrence from posttherapeutic changes. Lower apparent diffusion coefficients (ADCs) have been reported in the head and neck region of adults and children for most malignant lesions, as compared with ADCs of benign lesions. For nodal staging, DW imaging has shown promise in helping detect lymph node metastases, even in small (subcentimeter) nodes with lower ADCs, as compared with normal or reactive nodes. Follow-up of early response to treatment is reflected in an ADC increase in the primary tumor and nodal metastases; whereas nonresponding lesions tend to reveal only a slight increase or even a decrease in ADC during follow-up. Optimization and standardization of DW imaging technical parameters, comparison of DW images with morphologic images, and increasing experience, however, are prerequisites for successful application of this challenging technique in the evaluation of various head and neck pathologic conditions.

Three-year follow-up of human transplanted kidneys by diffusion-weighted MRI and blood oxygenation level-dependent imaging

PURPOSE

To prospectively determine the 3-year stability and potential changes of functional parameters in renal allograft recipients obtained from diffusion-weighted imaging (DWI) and blood oxygenation level-dependent (BOLD) MRI.

MATERIALS AND METHODS

Nine renal allograft recipients underwent DWI and BOLD-MRI twice, once 7 ± 3 months after transplantation, and again 32 ± 2 months after the first MRI. DWI yielded an apparent diffusion coefficient (ADC) and the perfusion contribution (F(P) ). BOLD imaging yielded R2, providing an estimation of renal oxygenation. Coefficients of variation between (CV(b) ) and within subjects (CV(w) ) were calculated.

RESULTS

The parameters were stable after 32 months in eight of the nine patients, who had well-functioning allografts. Mean diffusion values were very similar in the first and second scan. CV(w) and CV(b) for ADC values were less than 3.5% and 5.9%, respectively, in cortex and medulla, but were higher for F(P) (15%-18%). CV(w) and CV(b) of R2 were also low (medulla: CV(w) = 10.8%, CV(b) = 11.4%; cortex: CV(w) and CV(b) = 7.2%). R2 increased significantly (P = 0.035) in cortex but not in medulla, suggesting reduced cortical oxygen content. One subject with decreased glomerular filtration rate demonstrated strongly altered parameters.

CONCLUSION

In the absence of graft dysfunction, DWI and BOLD imaging yield consistent results over 3 years in stable human renal allograft recipients.

Potential and limitations of diffusion-weighted magnetic resonance imaging in kidney, prostate, and bladder cancer including pelvic lymph node staging: a critical analysis of the literature

CONTEXT

Diagnosis, staging, and treatment monitoring are still suboptimal for most genitourinary tumours. Diffusion-weighted magnetic resonance imaging (DW-MRI) has already shown promise as a noninvasive imaging modality in the early detection of microstructural and functional changes in several pathologies of various organs.

OBJECTIVE

To assess the potential and limitations of DW-MRI in the management of patients with kidney, prostate, and bladder cancer.

EVIDENCE ACQUISITION

A nonsystematic literature search using the Medline/PubMed and Embase databases for full-length papers reporting on DW-MRI for kidney, prostate, and bladder cancer was performed up to August 1, 2011. Only those articles with complete data reporting on DW-MRI applications with potential implications in solving commonly encountered clinical challenges relating to tumour detection, staging, and treatment monitoring were finally examined.

EVIDENCE SYNTHESIS

For kidney tumours DW-MRI is a reasonable alternative to conventional cross-sectional imaging to detect and characterise focal renal lesions, especially in patients with impaired renal function. For prostate cancer, DW-MRI applied in addition to conventional T2-weighted and contrast-enhanced magnetic resonance imaging (MRI) improves tumour detection and localisation. In addition, it has shown promise for the assessment of tumour aggressiveness and for treatment monitoring during active surveillance, radiation therapy, and focal therapy. For bladder cancer, DW-MRI may improve the performance of conventional T2-weighted and contrast-enhanced MRI in the work-up of bladder cancer, helping to differentiate non-muscle-invasive from muscle-invasive tumours. For pelvic lymph nodes, initial results showed the potential to improve nodal staging of prostate and bladder cancer compared with conventional cross-sectional imaging.

CONCLUSIONS

DW-MRI holds promise to ameliorate the management of patients with kidney, prostate, and bladder cancer including pelvic lymph node staging. Current limitations include the lack of standardisation of the technique across multiple centres and the still limited expertise.

Diffusion-weighted MR imaging of native and transplanted kidneys

Applications of diffusion-weighted (DW) magnetic resonance (MR) imaging outside the brain have gained increasing importance in recent years. Owing to technical improvements in MR imaging units and faster sequences, the need for noninvasive imaging without contrast medium administration, mainly in patients with renal insufficiency, can be met successfully by applying this technique. DW MR imaging is quantified by the apparent diffusion coefficient (ADC), which provides information on diffusion and perfusion simultaneously. By using a biexponential fitting process of the DW MR imaging data, these two entities can be separated, because this type of fitting process can serve as an estimate of both the perfusion fraction and the true diffusion coefficient. DW MR imaging can be applied for functional evaluation of the kidneys in patients with acute or chronic renal failure. Impairment of renal function is accompanied by a decreased ADC. Acute ureteral obstruction leads to perfusion and diffusion changes in the affected kidney, and renal artery stenosis results in a decreased ADC. In patients with pyelonephritis, diffuse or focal changes in signal intensity are seen on the high-b-value images, with increased signal intensity corresponding to low signal intensity on the ADC map. The feasibility and reproducibility of DW MR imaging in patients with transplanted kidneys have already been demonstrated, and initial results seem to be promising for the assessment of allograft deterioration. Overall, performance of renal DW MR imaging, presuming that measurements are of high quality, will further boost this modality, particularly for early detection of diffuse renal conditions, as well as more accurate characterization of focal renal lesions.

Diffusion-weighted MRI in head and neck radiology: applications in oncology

Extracranial application of diffusion-weighted magnetic resonance imaging (MRI) has gained increasing importance in recent years. As a result of technical advances, this new non-invasive functional technique has also been applied in head and neck radiology for several clinical indications. In cancer imaging, diffusion-weighted MRI can be performed for tumour detection and characterization, monitoring of treatment response as well as the differentiation of recurrence and post-therapeutic changes after radiotherapy. Even for lymph node staging promising results have been reported recently. This review article provides overview of potential applications of diffusion-weighted MRI in head and neck with the main focus on its applications in oncology.

Predicting and monitoring cancer treatment response with diffusion-weighted MRI

An imaging biomarker that would provide for an early quantitative metric of clinical treatment response in cancer patients would provide for a paradigm shift in cancer care. Currently, nonimage based clinical outcome metrics include morphology, clinical, and laboratory parameters, however, these are obtained relatively late following treatment. Diffusion-weighted MRI (DW-MRI) holds promise for use as a cancer treatment response biomarker as it is sensitive to macromolecular and microstructural changes which can occur at the cellular level earlier than anatomical changes during therapy. Studies have shown that successful treatment of many tumor types can be detected using DW-MRI as an early increase in the apparent diffusion coefficient (ADC) values. Additionally, low pretreatment ADC values of various tumors are often predictive of better outcome. These capabilities, once validated, could provide for an important opportunity to individualize therapy thereby minimizing unnecessary systemic toxicity associated with ineffective therapies with the additional advantage of improving overall patient health care and associated costs. In this report, we provide a brief technical overview of DW-MRI acquisition protocols, quantitative image analysis approaches and review studies which have implemented DW-MRI for the purpose of early prediction of cancer treatment response.