Christoph Wald

Report of a national conference on liver allocation in patients with hepatocellular carcinoma in the United States.

A national conference was held to better characterize the long‐term outcomes of liver transplantation (LT) for patients with hepatocellular carcinoma (HCC) and to assess whether it is justified to continue the policy of assigning increased priority for candidates with early‐stage HCC on the transplant waiting list in the United States. The objectives of the conference were to address specific HCC issues as they relate to liver allocation, develop a standardized pathology report form for the assessment of the explanted liver, develop more specific imaging criteria for HCC designed to qualify LT candidates for automatic Model for End‐Stage Liver Disease (MELD) exception points without the need for biopsy, and develop a standardized pretransplant imaging report form for the assessment of patients with liver lesions. At the completion of the meeting, there was agreement that the allocation policy should result in similar risks of removal from the waiting list and similar transplant rates for HCC and non‐HCC candidates. In addition, the allocation policy should select HCC candidates so that there are similar posttransplant outcomes for HCC and non‐HCC recipients. There was a general consensus for the development of a calculated continuous HCC priority score for ranking HCC candidates on the list that would incorporate the calculated MELD score, alpha‐fetoprotein, tumor size, and rate of tumor growth. Only candidates with at least stage T2 tumors would receive additional HCC priority points. Liver Transpl 16:262–278, 2010.

New OPTN/UNOS Policy for Liver Transplant Allocation: Standardization of Liver Imaging, Diagnosis, Classification, and Reporting of Hepatocellular Carcinoma

A new liver allocation policy featuring improved imaging criteria for hepatocellular carcinoma exceptions has been developed and approved by the Organ Procurement and Transplantation Network–United Network for Organ Sharing, in late 2011; radiologists in accredited transplantation centers in the United States are now challenged to implement the policy.

Long-Term Follow-up After an Initial Episode of Diverticulitis: What Are the Predictors of Recurrence?

PURPOSE: The purpose of our study was to determine the clinical and CT predictors of recurrent disease after a first episode of diverticulitis that was successfully managed nonoperatively. METHODS: We retrospectively analyzed 954 consecutive patients who presented to our institution with diverticulitis from 2002 to 2008. Patients were identified with International Classification of Diseases, 9th Revision/Current Procedural Terminology codes. Patients were excluded if they had subsequent colectomy based on the first attack (n = 81), or if the attack they had between 2002 and 2008 was not their first attack (n = 201). We evaluated CT variables chosen by a panel of expert gastrointestinal radiologists. These radiologists reviewed the available published literature for CT imaging characteristics thought to predict diverticulitis severity. CT variables (n = 20) were determined by prospective reevaluation of scans by blinded study radiologists. Clinical variables (n = 43) were coded based on a retrospective chart review. Univariate analysis of variables in relation to recurrent disease was performed by a log-rank test of Kaplan-Meier estimates. Multivariate analysis was performed using Cox proportional hazards modeling. Variables with P < .2 on univariate analysis were included in a stepwise selection algorithm. RESULTS: The study population included 672 patients; mean age, 61 ± 15 years; mean follow-up, 42.8 ± 24 months. The index presentation of diverticulitis was most commonly located in the sigmoid colon (72%), followed by descending colon (33%), right colon (5%), and transverse colon (3%). Overall recurrence at 5 years was 36% by (95% CI 31.4%–40.6%) Kaplan-Meier estimate. Complicated recurrence (fistula, abscess, free perforation) occurred in 3.9% (95% CI 2.2%–5.6%) of patients at 5 years by Kaplan-Meier estimate. Family history of diverticulitis (HR 2.2, 95% CI 1.4–3.2), length of involved colon >5 cm (HR 1.7, 95% CI 1.3–2.3), and retroperitoneal abscess (HR 4.5, 95% CI 1.1–18.4) were associated with diverticulitis recurrence. Right colon disease (HR 0.27, 95% CI 0.09–0.86) was associated with freedom from recurrence. CONCLUSION: Although diverticulitis recurrence is common following an initial attack that has been managed medically, complicated recurrence is uncommon. Patients who present with a family history of diverticulitis, long segment of involved colon, and/or retroperitoneal abscess are at higher risk for recurrent disease. Patients who present with right-sided diverticulitis are at low risk for recurrent disease. These findings should be taken into consideration when counseling patients regarding the potential benefits of prophylactic colectomy.

Performance of ACR Lung-RADS in a Clinical CT Lung Screening Program

PURPOSE The aim of this study was to assess the effect of applying ACR Lung-RADS in a clinical CT lung screening program on the frequency of positive and false-negative findings. METHODS Consecutive, clinical CT lung screening examinations performed from January 2012 through May 2014 were retroactively reclassified using the new ACR Lung-RADS structured reporting system. All examinations had initially been interpreted by radiologists credentialed in structured CT lung screening reporting following the National Comprehensive Cancer Networks Clinical Practice Guidelines in Oncology: Lung Cancer Screening (version 1.2012), which incorporated positive thresholds modeled after those in the National Lung Screening Trial. The positive rate, number of false-negative findings, and positive predictive value were recalculated using the ACR Lung-RADS-specific positive solid/part-solid nodule diameter threshold of 6 mm and nonsolid (ground-glass) threshold of 2 cm. False negatives were defined as cases reclassified as benign under ACR Lung-RADS that were diagnosed with malignancies within 12 months of the baseline examination. RESULTS A total of 2,180 high-risk patients underwent baseline CT lung screening during the study interval; no clinical follow-up was available in 577 patients (26%). ACR Lung-RADS reduced the overall positive rate from 27.6% to 10.6%. No false negatives were present in the 152 patients with >12-month follow-up reclassified as benign. Applying ACR Lung-RADS increased the positive predictive value for diagnosed malignancy in 1,603 patients with follow-up from 6.9% to 17.3%. CONCLUSIONS The application of ACR Lung-RADS increased the positive predictive value in our CT lung screening cohort by a factor of 2.5, to 17.3%, without increasing the number of examinations with false-negative results.

Improved Survival After Live Donor Adult Liver Transplantation (LDALT) Using Right Lobe Grafts: Program Experience and Lessons Learned

We present our program experience with 85 live donor adult liver transplantation (LDALT) procedures using right lobe grafts with five simultaneous live donor kidney transplants using different donors performed over a 6‐year period. After an ‘early’ 2‐year experience of 25 LDALT procedures, program improvements in donor and recipient selection, preoperative imaging, donor and recipient surgical technique and immunosuppressive management significantly reduced operative mortality (16% vs. 3.3%, p = 0.038) and improved patient and graft 1‐year survival in recipients during our ‘later’ experience with the next 60 cases (January 2001 and March 2005; patient survival: early 70.8% vs. later 92.7%, p = 0.028; graft survival: Early 64% vs. later 91.1%, p = 0.019, respectively). Overall patient and graft survival were 82% and 80%. There was a trend for less postoperative complications (major and minor) with program experience (early 88% vs. later 66.7%; p = 0.054) but overall morbidity remained at 73.8%. Biliary complications (cholangitis, disruption, leak or stricture) were not influenced by program experience (early 32% vs. later 38%). Liver volume adjusted to 100% of standard liver volume (SLV) within 1 month post‐transplant. Despite a high rate of morbidity after LDALT, excellent patient and graft survival can be achieved with program experience.

Imaging diagnosis and staging of hepatocellular carcinoma

Jeong Min Lee, Franco Trevisani, Valerie Vilgrain, and Christoph Wald Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; Unit of Medical Symptomatology, Department of Clinical Medicine, University of Bologna, Bologna, Italy; Department of Radiology, Beaujon Hospital, Université Paris 7, Assistance Publique–Hôpitaux de Paris, Paris, France; and Lahey Clinic Medical Center, Tufts University Medical School, Burlington, MA

Initial experience with a free, high-volume, low-dose CT lung cancer screening program.

The National Lung Screening Trial demonstrated a significant mortality benefit for patients at high risk for lung cancer undergoing serial low-dose CT. Currently, the National Comprehensive Cancer Network and several United States-based professional associations recommend CT Lung screening for high-risk patients. In the absence of established reimbursement, the authors modeled and implemented a free low-dose CT lung cancer screening program to provide equitable access to all eligible patients. Elements of the program reported in this article include a decentralized referral network, centralized program coordination, structured reporting, and a patient data management system. The experience and initial results observed in this clinical setting closely match the performance metrics of the National Lung Screening Trial with regard to cancer detection and incidental findings rates. To eliminate health care disparities a vigorous lobbying effort will be needed to expedite reimbursement and make CT lung screening equally available to all patients at high-risk.

Segmentation of artifacts and anatomy in CT metal artifact reduction

PURPOSE Metal objects present in x-ray computed tomography (CT) scans are accompanied by physical phenomena that render CT projections inconsistent with the linear assumption made for analytical reconstruction. The inconsistencies create artifacts in reconstructed images. Metal artifact reduction algorithms replace the inconsistent projection data passing through metals with estimates of the true underlying projection data, but when the data estimates are inaccurate, secondary artifacts are generated. The secondary artifacts may be as unacceptable as the original metal artifacts; therefore, better projection data estimation is critical. This research uses computer vision techniques to create better estimates of the underlying projection data using observations about the appearance and nature of metal artifacts. METHODS The authors developed a method of estimating underlying projection data through the use of an intermediate image, called the prior image. This method generates the prior image by segmenting regions of the originally reconstructed image, and discriminating between regions that are likely to be metal artifacts and those that are likely to represent anatomical structures. Regions identified as metal artifact are replaced with a constant soft-tissue value, while structures such as bone or air pockets are preserved. This prior image is reprojected (forward projected), and the reprojections guide the estimation of the underlying projection data using previously published interpolation techniques. The algorithm is tested on head CT test cases containing metal implants and compared against existing methods. RESULTS Using the new method of prior image generation on test images, metal artifacts were eliminated or reduced and fewer secondary artifacts were present than with previous methods. The results apply even in the case of multiple metal objects, which is a challenging problem. The authors did not observe secondary artifacts that were comparable to or worse than the original metal artifacts, as sometimes occurred with the other methods. The accuracy of the prior was found to be more critical than the particular interpolation method. CONCLUSIONS Metals produce predictable artifacts in CT images of the head. Using the new method, metal artifacts can be discriminated from anatomy, and the discrimination can be used to reduce metal artifacts.

Coronary CTA assessment of coronary anomalies

Coronary anomalies occur in <1% of the general population and can range from a benign incidental finding to the cause of sudden cardiac death. The coronary anomalies are classified here according to the traditional grouping into those of origin and course, intrinsic arterial anatomy, and termination. Classic coronary anomalies of origin and course include those in which a coronary artery originates from the contralateral aortic sinus or the pulmonary artery with anomalous course. Single coronary artery anomalies, in which single coronary artery branches to supply the entire coronary tree, are also included in this category. Anomalies of intrinsic arterial anatomy are a broad class that includes myocardial bridges, coronary ectasia and aneurysms, subendocardial coursing arteries, and coronary artery duplication. Coronary anomalies of termination are those in which a coronary artery terminates in a fistulous connection to a great vessel or cardiac chamber. In the case of those anomalies associated with a risk of sudden cardiac death, the relevant imaging features on CT angiography (CTA) associated with poorer prognosis are reviewed. Recent guidelines and appropriateness criteria favor the use of coronary CTA for the evaluation of coronary anomalies. Although invasive angiography has historically been used to diagnose coronary anomalies, multidetector CT imaging techniques have now become an accurate noninvasive alternative. Cardiac CTA provides excellent spatial and temporal resolution, allowing accurate anatomical assessment of these anomalies.

Variability of Standard Liver Volume Estimation Versus Software-Assisted Total Liver Volume Measurement

The estimation of the standard liver volume (SLV) is an important component of the evaluation of potential living liver donors and the surgical planning for resection for tumors. At least 16 different formulas for estimating SLV have been published in the worldwide literature. More recently, several proprietary software‐assisted image postprocessing (SAIP) programs have been developed to provide accurate volume measurements based on the actual anatomy of a specific patient. Using SAIP, we measured SLV in 375 healthy potential liver donors and compared the results to SLV values that were estimated with the previously published formulas and each donors demographic and anthropomorphic data. The percentage errors of the 16 SLV formulas versus SAIP varied by more than 59% (from −21.6% to +37.7%). One formula was not statistically different from SAIP with respect to the percentage error (−1.2%), and another formula was not statistically different with respect to the absolute liver volume (18 mL). More than 75% of the estimated SLV values produced by these 2 formulas had percentage errors within ±15%, and the formulas provided good predictions within acceptable agreement (±15%) on scatter plots. Because of the wide variability, care must be taken when a formula is being chosen for estimating SLV, but the 2 aforementioned formulas provided the most accurate results with our patient demographics. Liver Transpl, 2012.