Abdominal MRI on a Commercial 0.55T System: Initial Evaluation and Comparison to Higher Field Strengths.

RATIONALE AND OBJECTIVES: This study aims to assess the quality of abdominal MR images acquired on a commercial 0.55T scanner and compare these images with those acquired on conventional 1.5T/3T scanners in both healthy subjects and patients. MATERIALS AND METHODS: Fifteen healthy subjects and 52 patients underwent abdominal Magnetic Resonance Imaging at 0.55T. Images were also collected in healthy subjects at 1.5T, and comparison 1.5/3T images identified for 28 of the 52 patients. Image quality was rated by two radiologists on a 4-point Likert scale. Readers were asked whether they could answer the clinical question for patient studies. Wilcoxon signed-rank test was used to test for significant differences in image ratings and acquisition times, and inter-reader reliability was computed. RESULTS: The overall image quality of all sequences at 0.55T were rated as acceptable in healthy subjects. Sequences were modified to improve signal-to-noise ratio and reduce artifacts and deployed for clinical use; 52 patients were enrolled in this study. Radiologists were able to answer the clinical question in 52 (reader 1) and 46 (reader 2) of the patient cases. Average image quality was considered to be diagnostic (>3) for all sequences except arterial phase FS 3D T1w gradient echo (GRE) and 3D magnetic resonance cholangiopancreatography for one reader. In comparison to higher field images, significantly lower scores were given to 0.55T IP 2D GRE and arterial phase FS 3D T1w GRE, and significantly higher scores to diffusion-weighted echo planar imaging at 0.55T; other sequences were equivalent. The average scan time at 0.55T was 54 ± 10 minutes vs 36 ± 11 minutes at higher field strengths (P < .001). CONCLUSION: Diagnostic-quality abdominal MR images can be obtained on a commercial 0.55T scanner at a longer overall acquisition time compared to higher field systems, although some sequences may benefit from additional optimization.

Imaging findings of the injured in the massive Beirut blast.

PURPOSE: (1) Describe imaging utilization and findings within two weeks of the 2020 Beirut blast according to the mechanism of injury, (2) determine the appropriate imaging modality per organ/system, and (3) describe changes in the workflow of a radiology department to deal with massive crises. MATERIALS AND METHODS: Two hundred sixty patients presented to the largest emergency department in Beirut and underwent imaging within 2 weeks of the blast. In this retrospective study, patients were divided into early (1) and late (2) imaging groups. Patients' demographic, outcome, type and time of imaging studies, body parts imaged, and mechanism and types of injuries were documented. RESULTS: Two hundred five patients in group 1 underwent 502 and 55 patients in group 2 underwent 145 imaging studies. Tertiary blast injuries from direct impact and falling objects were the most common type of injuries followed by secondary (shrapnel) injuries. Both types of injuries affected mostly the head and neck and upper extremities. Plain radiographs were adequate for the extremities and CT for the head and neck. A regularly updated and practiced emergency plan is essential to mobilize staff and equipment and efficiently deliver radiology services during crises. CONCLUSION: Because the powerful Beirut blast occurred at the port located in the periphery of the city, most injuries seen on imaging were of the upper extremities and head and neck caused by the severe blast wind or penetrating shrapnel and resulted from people using their arms to protect their heads and bodies from direct impact and falling objects.

Quality assessment of routine brain imaging at 0.55 T: initial experience in a clinical workflow.

The purpose of this study was to assess the quality of clinical brain imaging in healthy subjects and patients on an FDA-approved commercial 0.55 T MRI scanner, and to provide information about the feasibility of using this scanner in a clinical workflow. In this IRB-approved study, brain examinations on the scanner were prospectively performed in 10 healthy subjects (February-April 2022) and retrospectively derived from 44 patients (February-July 2022). Images collected using the following pulse sequences were available for assessment: axial DWI (diffusion-weighted imaging), apparent diffusion coefficient maps, 2D axial fluid-attenuated inversion recovery images, axial susceptibility-weighted images (both magnitude and phase), sagittal T1 -weighted (T1w) Sampling Perfection with Application Optimized Contrast images, sagittal T1w MPRAGE (magnetization prepared rapid gradient echo) with contrast enhancement, axial T1w turbo spin echo (TSE) with and without contrast enhancement, and axial T2 -weighted TSE. Two readers retrospectively and independently evaluated image quality and specific anatomical features in a blinded fashion on a four-point Likert scale, with a score of 1 being unacceptable and 4 being excellent, and determined the ability to answer the clinical question in patients. For each category of image sequences, the mean, standard deviation, and percentage of unacceptable quality images (<2) were calculated. Acceptable (rating ≥ 2) image quality was achieved at 0.55 T in all sequences for patients and 85% of the sequences for healthy subjects. Radiologists were able to answer the clinical question in all patients scanned. In total, 50% of the sequences used in patients and about 60% of the sequences used in healthy subjects exhibited good (rating ≥ 3) image quality. Based on these findings, we conclude that diagnostic quality clinical brain images can be successfully collected on this commercial 0.55 T scanner, indicating that the routine brain imaging protocol may be deployed on this system in the clinical workflow.

Metreleptin therapy for nonalcoholic steatohepatitis: Open-label therapy interventions in two different clinical settings.

BACKGROUND: Recombinant leptin therapy reverses nonalcoholic steatohepatitis (NASH) in leptin-deficient lipodystrophy. We inquired if leptin therapy would improve nonalcoholic steatohepatitis in more common forms of this heterogeneous condition. METHODS: Nine male patients with relative leptin deficiency (level < 25th percentile of body mass index- and gender-matched United States population) and biopsy-proven NASH and 23 patients with partial lipodystrophy and NASH were recruited for two distinctive open-label trials. Participants received leptin therapy in the form of metreleptin for 12 months. The primary endpoints were the global nonalcoholic steatohepatitis scores from paired liver biopsies scored blindly. FINDINGS: Of 9 participants recruited in the relative leptin deficiency treatment study, 7 completed 12-months of therapy. Mean global NASH scores were reduced from 8 ± 3 to 5 ± 2 (range: from 1 to 6, P = 0.004). In the partial lipodystrophy study, 19 of 22 subjects completed 12 months of treatment, and 18 completed a second liver biopsy. Global NASH scores also reduced significantly from 6 ± 2 to 5 ± 2 (range: from -2 to 4, P = 0.008). In both studies, the predominant changes were in steatosis and hepatic injury scores. CONCLUSION: Our findings show that patients with NASH associated with both relative leptin deficiency and partial lipodystrophy have reductions in hepatic steatosis and injury in response to exogenous leptin therapy. Moreover, leptin deficiency may have regulatory effects in mediating fat deposition and ensuing injury in the liver.TRIAL REGISTRATION. ClinicalTrials.gov NCT00596934 and NCT01679197.

Management of patients with high-risk and advanced prostate cancer in the Middle East: resource-stratified consensus recommendations.

PURPOSE: Prostate cancer care in the Middle East is highly variable and access to specialist multidisciplinary management is limited. Academic tertiary referral centers offer cutting-edge diagnosis and treatment; however, in many parts of the region, patients are managed by non-specialists with limited resources. Due to many factors including lack of awareness and lack of prostate-specific antigen (PSA) screening, a high percentage of men present with locally advanced and metastatic prostate cancer at diagnosis. The aim of these recommendations is to assist clinicians in managing patients with different levels of access to diagnostic and treatment modalities. METHODS: The first Advanced Prostate Cancer Consensus Conference (APCCC) satellite meeting for the Middle East was held in Beirut, Lebanon, November 2017. During this meeting a consortium of urologists, medical oncologists, radiation oncologist and imaging specialists practicing in Lebanon, Syria, Iraq, Kuwait and Saudi Arabia voted on a selection of consensus questions. An additional workshop to formulate resource-stratified consensus recommendations was held in March 2019. RESULTS: Variations in practice based on available resources have been proposed to form resource-stratified recommendations for imaging at diagnosis, initial management of localized prostate cancer requiring therapy, treatment of castration-sensitive/naïve advanced prostate cancer and treatment of castration-resistant prostate cancer. CONCLUSION: This is the first regional consensus on prostate cancer management from the Middle East. The following recommendations will be useful to urologists and oncologists practicing in all areas with limited access to specialist multi-disciplinary teams, diagnostic modalities and treatment resources.

MRI evaluation of the placenta from normal variants to abnormalities of implantation and malignancies.

Even though the placenta has been known for millennia, it is still considered one of the most complex and least understood human organs. Imaging of the placenta is gaining attention due to its impact on fetal and maternal outcomes. MRI plays a vital role in evaluation of inconclusive cases by ultrasonography. It enables precise mapping of placental abnormalities for proper multidisciplinary planning and management. In this article we provide a comprehensive in-depth review of the role of antenatal MR in evaluating "The Placenta." We will describe the protocols and techniques used for MRI of the placenta, review anatomy of the placenta, describe MRI features of major placental abnormalities including those related to position, depth of implantation, hemorrhage, gestational trophoblastic neoplasia, and retained products of conception and discuss the added value of MRI in the management and preoperative planning of such abnormalities. Level of Evidence: 3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1702-1717.

Iron-Containing Abdominal Pathologies: Exploiting Magnetic Susceptibility Artifact on Dual-Echo Gradient-Echo Magnetic Resonance Imaging.

A multitude of pathologic entities involve abnormal iron deposition in the abdomen. These lesions demonstrate decreased signal on longer magnetic resonance sequences with longer echo time due to T2* effect. Dual-echo gradient-echo sequences demonstrate increased susceptibility artifact with longer echo sequences. In this article, the spectrum of iron-containing abdominal pathologies is illustrated, with their characteristic distributions. Included is a brief discussion of the physics of magnetic resonance imaging of iron-containing lesions.

Diagnostic accuracy of MRI with extracellular vs. hepatobiliary contrast material for detection of residual hepatocellular carcinoma after locoregional treatment.

PURPOSE: To compare the diagnostic accuracy of extracellular gadolinium-based contrast-enhanced MRI (Gd-MRI) and gadoxetic acid-enhanced MRI (EOB-MRI) for the assessment of hepatocellular carcinoma (HCC) response to locoregional therapy (LRT) using explant correlation as the reference standard. METHODS: Forty-nine subjects with cirrhosis and HCC treated with LRT who underwent liver MRI using either Gd-MRI (n = 26) or EOB-MRI (n = 23) within 90 days of liver transplantation were included. Four radiologists reviewed the MR images blinded to histology to determine the size and percentage of viable residual HCC using a per-lesion explant reference standard. Sensitivities, specificities, accuracies, and agreement with histology for the detection residual HCC were calculated. RESULTS: Gd-MRI had greater agreement with histology (ICC: 0.98 [0.95-0.99] vs. 0.80 [0.63-0.90]) and greater sensitivity for viable HCC (76% [13/17 50-93%] vs. 58% [7/12; 28-85%]) than EOB-MRI; specificities were similar (84% [16/19; 60-97%] vs. 85% [23/27; 66-96%]). Areas under ROC curves for detecting residual viable tumor were 0.80 (0.64-0.92) for Gd-MRI and 0.72 (0.55-0.85) for EOB-MRI. Gd-MRI had greater inter-rater agreement than EOB-MRI for determining the size of residual viable HCC (ICC: 0.96 [0.92-0.98] vs. 0.85 [0.72-0.92]). CONCLUSION: Gd-MRI may be more accurate and precise than EOB-MRI for the assessment of viable HCC following LRT.

Evidence Supporting LI-RADS Major Features for CT- and MR Imaging-based Diagnosis of Hepatocellular Carcinoma: A Systematic Review.

The Liver Imaging Reporting and Data System (LI-RADS) standardizes the interpretation, reporting, and data collection for imaging examinations in patients at risk for hepatocellular carcinoma (HCC). It assigns category codes reflecting relative probability of HCC to imaging-detected liver observations based on major and ancillary imaging features. LI-RADS also includes imaging features suggesting malignancy other than HCC. Supported and endorsed by the American College of Radiology (ACR), the system has been developed by a committee of radiologists, hepatologists, pathologists, surgeons, lexicon experts, and ACR staff, with input from the American Association for the Study of Liver Diseases and the Organ Procurement Transplantation Network/United Network for Organ Sharing. Development of LI-RADS has been based on literature review, expert opinion, rounds of testing and iteration, and feedback from users. This article summarizes and assesses the quality of evidence supporting each LI-RADS major feature for diagnosis of HCC, as well as of the LI-RADS imaging features suggesting malignancy other than HCC. Based on the evidence, recommendations are provided for or against their continued inclusion in LI-RADS. © RSNA, 2017 Online supplemental material is available for this article.

Imaging Findings Within the First 12 Months of Hepatocellular Carcinoma Treated With Stereotactic Body Radiation Therapy.

PURPOSE: To correlate the imaging findings of treated hepatocellular carcinoma (HCC) after stereotactic body radiation therapy (SBRT) with explant pathology and alpha-fetoprotein (AFP) response. METHODS AND MATERIALS: From 2007 to 2015, of 146 patients treated with liver SBRT for Barcelona Clinic Liver Cancer stage A hepatocellular carcinoma, 10 were identified with inclusion criteria and had regular interval follow-up magnetic resonance imaging/triple phase computed tomography and explant pathology or declining AFP values for radiology-pathology response correlation. Reference standards for successful response were >90% necrosis on explant pathology or pretreatment AFP >75 ng/mL normalizing to <10 ng/mL within 1 year after SBRT without other treatment. Subjects were treated with 24 to 50 Gy in 3 to 5 fractions. Multiphasic magnetic resonance imaging or computed tomography performed at 3, 6, 9, and 12 months after SBRT was compared with pretreatment imaging by 2 expert radiologists. Descriptive statistics were calculated. RESULTS: There were 10 subjects with 10 treated HCCs, classified as 3 Organ Procurement and Transplantation Network (OPTN) 5a, 4 OPTN 5b, and 3 OPTN 5x. All had successfully treated HCCs, according to explant pathology or declining AFP. Four of 10 HCCs had persistent central arterial hyperenhancement 3 to 12 months after SBRT; persistent wash-out was common up to 12 months (9 of 10). Of 10 treated HCCs, 9 exhibited decreased size at 12 months. Liver parenchyma adjacent to the lesion showed early (3-6 months) hyperemia followed by late (6-12 months) capsular retraction and delayed enhancement. No patient had a significant decline in liver function. CONCLUSIONS: In the absence of increasing size, persistent central arterial hyperenhancement and wash-out can occur within the first 12 months after SBRT in successfully treated HCCs and may not represent residual viable tumor. Liver parenchyma adjacent to the treated lesion showed inflammation followed by fibrosis, without significant change in hepatic function. Until a radiologic signature of tumor control is determined, freedom from local progression seems to be the best measure of HCC control after SBRT.

Effect of Gadoxetate Disodium on Arterial Phase Respiratory Waveforms Using a Quantitative Fast Fourier Transformation-Based Analysis.

OBJECTIVE: The purpose of this study is to investigate the effect of gadoxetate disodium administration on arterial phase respiratory waveforms. SUBJECTS AND METHODS: From 2013 to 2015, 107 subjects undergoing liver MRI with either gadoxetate disodium (10 mL diluted 1:1 with saline; injection rate, 2 mL/s; n = 40) or gadobenate dimeglumine (0.2 mL/kg; maximum, 20 mL; injection rate, 2 mL/s; n = 67) were enrolled. Respiratory waveforms obtained during unenhanced and dynamic contrast-enhanced phases were filtered by a physicist, who was blinded to contrast agent and imaging phase, to eliminate electronic and cardiac noise using fast Fourier transformation. The average root-mean-square difference of two intrasubject control phases (unenhanced and late dynamic) was termed D1, and the root-mean-square deviation of the arterial phase referent to the control record mean was termed D2. D1, D2, and their difference were compared across agents with the Mann-Whitney U test. Bland-Altman plots were generated for D1 and D2 values. RESULTS: D1 values were similar for both agents (mean [± SD], 232 ± 203 for gadoxetate vs 201 ± 230 for gadobenate; p = 0.48), indicating similar intercohort baseline breath-holding capability. D2 was greater and more variable for the gadoxetate cohort (438 ± 381) than for the gadobenate cohort (167 ± 167; p < 0.001), indicating larger and more unpredictable respiratory waveform deviations isolated to the arterial phase (subject-level rate, 48% [19/40] for gadoxetate vs 1% [1/67] for gadobenate; p < 0.001). Aberrant respiratory waveform peaks in the arterial phase were usually associated with transient tachypnea (mean maximum arterial phase respiratory rate for the gadoxetate cohort, 27 breaths/min; range, 11-40 breaths/min). CONCLUSION: Fixed-dose gadoxetate disodium (10 mL; 1:1 dilution with 10 mL of saline; injection rate, 2 mL/s) transiently reduces breath-holding capacity during the arterial phase and is accompanied by brief transient tachypnea.

Reinterpretation of Outside Hospital MRI Abdomen Examinations in Patients With Cirrhosis: Is the OPTN Mandate Necessary?

OBJECTIVE: The objective of our study was to determine the relevance of a policy mandating reinterpretation of outside abdominal MRI examinations in patients with cirrhosis at risk for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A random subset (n = 125) of consecutive outside-hospital MRI abdomen examinations (n = 473) performed in subjects with cirrhosis and reinterpreted at a tertiary care center by one of 11 fellowship-trained radiologists was included. The original and reinterpreted reports were compared in consensus by two hepatobiliary imaging experts; one hepatologist determined the clinical impact. Each was blinded to outcome. The primary outcome was discrepancies relevant to the Organ Procurement and Transplantation Network (OPTN), including diagnosis of HCC and exceeding the Milan criteria for transplantation. Rates were compared with the McNemar test. RESULTS: HCC was diagnosed in 34% (43/125) of reinterpretations; of these, 44% (19/43) were concordant, 42% (18/43) originally were considered suspicious but not diagnostic of HCC, and 14% (6/43) were discordant. The Milan criteria were exceeded in 21% (26/125) of reinterpretations; of these, 73% (19/26) were concordant and 27% (7/26) were discordant. Overall, 10% (12/125) of subjects had a discrepant diagnosis of HCC, and 10% (12/125) of subjects had discrepant Milan status; 26% (11/43) of masses diagnosed to be HCC had been biopsied at the original institution. Original reports were significantly more likely to be missing major details (26% [32/125] vs 0.8% [1/125], p < 0.001) or difficult to understand (18% [23/125] vs 0.8% [1/125], p < 0.001). Predicted clinical management differed in 50% (62/125) of reinterpretations. CONCLUSION: The OPTN mandate for expert interpretation of liver MRI in patients with cirrhosis appears justified.

Imaging in Patients with Cirrhosis: Current Evidence.

There have been major changes in the management and reporting of hepatocellular carcinoma (HCC) in the last decade. Cross-sectional imaging is now pivotal in the management of cirrhotic patients, in particular in the diagnosis and staging of HCC. Although diagnostic systems have become relatively well developed, approximately one-third of HCC nodules may have an atypical appearance, necessitating ancillary testing, close follow-up, or biopsy. The introduction of standardized diagnostic and reporting systems has improved communication between radiologists and clinicians, but there remains substantial disagreement between radiologists in feature assignment and nodule characterization.

Predicting the likelihood of a persistent bile duct stone in patients with suspected choledocholithiasis: accuracy of existing guidelines and the impact of laboratory trends.

BACKGROUND: Existing guidelines aim to stratify the likelihood of choledocholithiasis to guide the use of ERCP versus a lower-risk diagnostic study such as EUS, MRCP, or intraoperative cholangiography. OBJECTIVE: To assess the performance of existing guidelines in predicting choledocholithiasis and to determine whether trends in laboratory parameters improve diagnostic accuracy. DESIGN: Retrospective cohort study. SETTING: Tertiary-care hospital. PATIENTS: Hospitalized patients presenting with suspected choledocholithiasis over a 6-year period. INTERVENTIONS: Assessment of the American Society for Gastrointestinal Endoscopy (ASGE) guidelines, its component variables, and laboratory trends in predicting choledocholithiasis. MAIN OUTCOME MEASUREMENTS: The presence of choledocholithiasis confirmed by EUS, MRCP, or ERCP. RESULTS: A total of 179 (35.9%) of the 498 eligible patients met ASGE high-probability criteria for choledocholithiasis on initial presentation. Of those, 99 patients (56.3%) had a stone/sludge on subsequent confirmatory test. Of patients not meeting high-probability criteria on presentation, 111 (34.8%) had a stone/sludge. The overall accuracy of the guidelines in detecting choledocholithiasis was 62.1% (47.4% sensitivity, 73% specificity) based on data available at presentation. The accuracy was unchanged when incorporating the second set of liver chemistries obtained after admission (63.2%), suggesting that laboratory trends do not improve performance. LIMITATIONS: Retrospective study, inconsistent timing of the second set of biochemical markers. CONCLUSION: In our cohort of patients, existing choledocholithiasis guidelines lacked diagnostic accuracy, likely resulting in overuse of ERCP. Incorporation of laboratory trends did not improve performance. Additional research focused on risk stratification is necessary to meet the goal of eliminating unnecessary diagnostic ERCP.

Respiratory motion artifact affecting hepatic arterial phase MR imaging with gadoxetate disodium is more common in patients with a prior episode of arterial phase motion associated with gadoxetate disodium.

PURPOSE: To determine, in a dual-center setting, whether patients who experience transient severe motion ( TSM transient severe motion ) in the arterial phase during gadoxetate disodium-enhanced magnetic resonance (MR) imaging are at higher risk for a subsequent episode of TSM transient severe motion than patients who do not have TSM transient severe motion during initial gadoxetate disodium administration. MATERIALS AND METHODS: Institutional review board approval was obtained for this retrospective, multi-institutional HIPAA-compliant study. The requirement for informed consent was waived. One hundred seventy patients each underwent two MR imaging examinations with bolus injection of gadoxetate disodium at one of two sites. Three radiologists reviewed the examinations at each site for TSM transient severe motion , based on severe arterial phase motion, despite minimal motion in the other dynamic phases. The occurrence rate of TSM transient severe motion in the second examination was compared between patients who had TSM transient severe motion in their first examination and those who did not by using the χ(2) or Fisher exact test, as appropriate. Relative risks and 95% confidence intervals ( CI confidence interval s) were calculated. RESULTS: TSM transient severe motion rates in second examinations were significantly higher for patients who had TSM transient severe motion in their first examination: site 1, 67% (six of nine) vs 4% (three of 69) (P < .0001); site 2, 60% (three of five) vs 6% (five of 87) (P < .005); and both sites, 64% (nine of 14) vs 5% (eight of 156) (P < .0001). Relative risks were 15 for site 1 (95% CI confidence interval : 5, 51), 10 for site 2 (95% CI confidence interval : 3, 32), and 13 for both sites (95% CI confidence interval : 6, 27). CONCLUSION: Patients who experience TSM transient severe motion during gadoxetate disodium-enhanced MR imaging are at significantly and substantially higher risk for TSM transient severe motion in the next gadoxetate disodium-enhanced examination compared with patients who do not have TSM transient severe motion during their initial gadoxetate disodium administration.

A pilot study of diffusion-weighted MRI in patients undergoing neoadjuvant chemoradiation for pancreatic cancer.

PURPOSE: In the current study we examined the ability of diffusion MRI (dMRI) to predict pathologic response in pancreatic cancer patients receiving neoadjuvant chemoradiation. METHODS: We performed a prospective pilot study of dMRI in patients with resectable pancreatic cancer. Patients underwent dMRI prior to neoadjuvant chemoradiation. Surgical specimens were graded according to the percent tumor cell destruction. Apparent diffusion coefficient (ADC) maps were used to generate whole-tumor derived ADC histogram distributions and mean ADC values. The primary objective of the study was to correlate ADC parameters with pathologic and CT response. RESULTS: Ten of the 12 patients enrolled on the study completed chemoradiation and had surgery. Three were found to be unresectable at the time of surgery and no specimen was obtained. Out of the 7 patients who underwent pancreaticoduodenectomy, 3 had a grade III histopathologic response (> 90% tumor cell destruction), 2 had a grade IIB response (51% to 90% tumor cell destruction), 1 had a grade IIA response (11% to 50% tumor cell destruction), and 1 had a grade I response (> 90% viable tumor). Median survival for patients with a grade III response, grade I-II response, and unresectable disease were 25.6, 18.7, and 6.1 months, respectively. There was a significant correlation between pre-treatment mean tumor ADC values and the amount of tumor cell destruction after chemoradiation with a Pearson correlation coefficient of 0.94 (P = .001). Mean pre-treatment ADC was 161 × 10(- 5) mm(2)/s (n = 3) in responding patients (> 90% tumor cell destruction) compared to 125 × 10(- 5) mm(2)/s (n = 4) in non-responding patients (> 10% viable tumor). CT imaging showed no significant change in tumor size in responders or non-responders. CONCLUSIONS: dMRI may be useful to predict response to chemoradiation in pancreatic cancer. In our study, tumors with a low ADC mean value at baseline responded poorly to standard chemoradiation and would be candidates for intensified therapy.

Imaging techniques for the diagnosis of hepatocellular carcinoma and the evaluation of response to treatment.

Imaging plays a critical role in the diagnosis of hepatocellular carcinoma (HCC). In the USA, non-invasive imaging based diagnosis of HCC has largely replaced biopsy because of the high specificity and positive predictive value of imaging features for HCC. Because of the important role of imaging and the need to promote standardization of the management of HCC, several imaging-based algorithms for the diagnosis of HCC in at-risk patients have been developed.Imaging also plays a vital role in the assessment of HCC response to locoregional therapies (LRT) such as ablative and endovascular therapies. Standard imaging response criteria of solid tumors that rely solely on change in tumor size for determination of therapeutic success are not applicable to HCC undergoing LRT. Therefore, several systems have been developed over the years to objectively evaluate HCC response to LRT.In this review, we will describe major and ancillary imaging features of HCC, how these features are incorporated into the various imaging based algorithms, discuss the differences between algorithms, and address the emerging role of new imaging techniques and contrast agents in the diagnosis of HCC. We will also discuss the importance of assessment of HCC response to LRT, describe patterns of imaging response to the various therapies including newer volumetric and functional response measures, and examine and compare proposed response criteria of HCC to LRT.