Paul Knechtges

ACR Colon Cancer Committee White Paper: Status of CT Colonography 2009

PURPOSE To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC). METHODS Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness. RESULTS Successful validation trials in screening cohorts both in the United States with ACRIN and in Germany demonstrated sensitivity > or = 90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp > or = 6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort. CONCLUSION Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.

Recommendations for MRI-based contouring of gross tumor volume and organs at risk for radiation therapy of pancreatic cancer

PURPOSE Local recurrence is a common and morbid event in patients with unresectable pancreatic adenocarcinoma. A more conformal and targeted radiation dose to the macroscopic tumor in nonmetastatic pancreatic cancer is likely to reduce acute toxicity and improve local control. Optimal soft tissue contrast is required to facilitate delineation of a target and creation of a planning target volume with margin reduction and motion management. Magnetic resonance imaging (MRI) offers considerable advantages in optimizing soft tissue delineation and is an ideal modality for imaging and delineating a gross tumor volume (GTV) within the pancreas, particularly as it relates to conformal radiation planning. Currently, no guidelines have been defined for the delineation of pancreatic tumors for radiation therapy treatment planning. Moreover, abdominal MRI sequences are complex and the anatomy relevant to the radiation oncologist can be challenging. The purpose of this study is to provide recommendations for delineation of GTV and organs at risk (OARs) using MRI and incorporating multiple MRI sequences. METHODS AND MATERIALS Five patients with pancreatic cancer and 1 healthy subject were imaged with MRI scans either on 1.5T or on 3T magnets in 2 separate institutes. The GTV and OARs were contoured for all patients in a consensus meeting. RESULTS An overview of MRI-based anatomy of the GTV and OARs is provided. Practical contouring instructions for the GTV and the OARs with the aid of MRI were developed and included in these recommendations. In addition, practical suggestions for implementation of MRI in pancreatic radiation treatment planning are provided. CONCLUSIONS With this report, we attempt to provide recommendations for MRI-based contouring of pancreatic tumors and OARs. This could lead to better uniformity in defining the GTV and OARs for clinical trials and in radiation therapy treatment planning, with the ultimate goal of improving local control while minimizing morbidity.

Assessment of treatment response during chemoradiation therapy for pancreatic cancer based on quantitative radiomic analysis of daily CTs: An exploratory study

Purpose In an effort for early assessment of treatment response, we investigate radiation induced changes in quantitative CT features of tumor during the delivery of chemoradiation therapy (CRT) for pancreatic cancer. Methods Diagnostic-quality CT data acquired daily during routine CT-guided CRT using a CT-on-rails for 20 pancreatic head cancer patients were analyzed. On each daily CT, the pancreatic head, the spinal cord and the aorta were delineated and the histograms of CT number (CTN) in these contours were extracted. Eight histogram-based radiomic metrics including the mean CTN (MCTN), peak position, volume, standard deviation (SD), skewness, kurtosis, energy and entropy were calculated for each fraction. Paired t-test was used to check the significance of the change of specific metric at specific time. GEE model was used to test the association between changes of metrics over time for different pathology responses. Results In general, CTN histogram in the pancreatic head (but not in spinal cord) changed during the CRT delivery. Changes from the 1st to the 26th fraction in MCTN ranged from -15.8 to 3.9 HU with an average of -4.7 HU (p<0.001). Meanwhile the volume decreased, the skewness increased (less skewed), and the kurtosis decreased (less peaked). The changes of MCTN, volume, skewness, and kurtosis became significant after two weeks of treatment. Patient pathological response is associated with the changes of MCTN, SD, and skewness. In cases of good response, patients tend to have large reductions in MCTN and skewness, and large increases in SD and kurtosis. Conclusions Significant changes in CT radiomic features, such as the MCTN, skewness, and kurtosis in tumor were observed during the course of CRT for pancreas cancer based on quantitative analysis of daily CTs. These changes may be potentially used for early assessment of treatment response and stratification for therapeutic intensification.

Utilizing the 5S Methodology for Radiology Workstation Design: Applying Lean Process Improvement Methods

p s t a o w n b fl The Toyota Production System, also known as Lean, is a quality improvement methodology developed by Toyota over the past 50 years to transform the automotive manufacturing process. This methodology has been tailored with success to health care environments [1]. Lean is a collection of tools coupled with an overall philosophy to deliver value by reducing waste through continuous improvement. Waste has a broad definition as anything that does not add value to a process [2]. Radiologists spend on average more than 8 hours a day in front of computers. Small inefficiencies, such as poor ergonomics, software application layouts, or desktop clutter, can lead to significant time loss and even potential injury. In one study of 73 radiologists in 2008, 58% reported repetitive stress symptoms, and 38% had prior diagnoses of repetitive stress syndrome [3]. Considering that diagnostic radiologists spend the majority of their time at their workstations, this is an area where the principles of 5S can be effectively used with only minimal investments of time and resources. In patient care, the value added of a diagnostic radiologist is largely defined by rendering accurate, timely diagnoses and reports. For radiologists, waste is any distraction that does not contribute to patient care (eg, time spent acclimating to different, unstandardized workstations or searching for frequently used information). Working in a clean, organized, and predictable environment can allow radiologists to spend more time with their eyes on the images and, ultimately, adding value to patient care.

Correlation of ADC With Pathological Treatment Response for Radiation Therapy of Pancreatic Cancer

PURPOSE: To investigate the feasibility of using apparent diffusion coefficient (ADC) to assesspathological treatment response in pancreatic ductal adenocarcinoma (PDAC) following neoadjuvant chemoradiation (nCR). MATERIALS/METHODS: MRI and pathological data collected for 25patients with resectable and borderline resectable PDAC following nCR were retrospectively analyzed. Pre- and post-nCR mean ADC values in the tumors were compared using Wilcoxon matched pairs test. Correlation of pathological treatment response and ADC values was assessed using Pearson’s correlation coefficient test and receiver-operating-curve (ROC) analysis. RESULTS: The average mean and standard deviation (SD) of the ADC values for all the patients analyzed were significantly higher in post-nCR (1.667±0.161×10-3) compared with those prior to nCR (1.395±0.136×10-3 mm2/sec), (P<0.05). The mean ADC values after nCR were significantly correlated with the pathological responses (r=-0.5172); P=0.02. The area under the curve (AUC) of the ADC values for differentiating G1, G2 and G3 pathological responses, using ROC analysis, was found to be 0.6310 and P=0.03. CONCLUSION: Changes of pre- and post-treatment ADC values significantly correlated with pathological treatment response for PDAC patients treated with chemoradiation therapy, indicating that the ADC could be used to assesstreatment response for PDAC.

Clinical Conundrum: Killian-Jamieson Diverticulum with Paraesophageal Hernia.

Killian-Jamieson diverticulum is a outpouching of the lateral cervical esophageal wall adjacent to the insertion of the recurrent laryngeal to the larynx and is much less common in clinical practice than Zenkers Diverticulum. Surgical management of Killian-Jamieson diverticulum requires open transcervical diverticulectomy due to the proximity of the recurrent laryngeal nerve to the base of the pouch. We present a case of a Killian-Jamieson diverticulum associated with a concurrent large type III paraesophageal hernia causing significant solid-food dysphagia, post-prandial regurgitation of solid foods, and chronic cough managed with open transcervical diverticulectomy and laparoscopic paraesophageal hernia repair with Nissen fundoplication.

Pancreatic gross tumor volume contouring on computed tomography (CT) compared with magnetic resonance imaging (MRI): Results of an international contouring conference

PURPOSE Accurate identification of the gross tumor volume (GTV) in pancreatic adenocarcinoma is challenging. We sought to understand differences in GTV delineation using pancreatic computed tomography (CT) compared with magnetic resonance imaging (MRI). METHODS AND MATERIALS Twelve attending radiation oncologists were convened for an international contouring symposium. All participants had a clinical and research interest in pancreatic adenocarcinoma. CT and MRI scans from 3 pancreatic cases were used for contouring. CT and MRI GTVs were analyzed and compared. Interobserver variability was compared using Dices similarity coefficient (DSC), Hausdorff distances, and Jaccard indices. Mann-Whitney tests were used to check for significant differences. Consensus contours on CT and MRI scans and constructed count maps were used to visualize the agreement. Agreement regarding the optimal method to determine GTV definition using MRI was reached. RESULTS Six contour sets (3 from CT and 3 from MRI) were obtained and compared for each observer, totaling 72 contour sets. The mean volume of contours on CT was significantly larger at 57.48 mL compared with a mean of 45.76 mL on MRI, P = .011. The standard deviation obtained from the CT contours was significantly larger than the standard deviation from the MRI contours (P = .027). The mean DSC was 0.73 for the CT and 0.72 for the MRI (P = .889). The conformity index measurement was similar for CT and MRI (P = .58). Count maps were created to highlight differences in the contours from CT and MRI. CONCLUSIONS Using MRI as a primary image set to define a pancreatic adenocarcinoma GTV resulted in smaller contours compared with CT. No differences in DSC or the conformity index were seen between MRI and CT. A stepwise method is recommended as an approach to contour a pancreatic GTV using MRI.

Fistula between the Jejunum and the Inferior Vena Cava after Esophagojejunal Anastomosis

Fistulas between the luminal gastrointestinal tract and vascular structures can result from a variety of etiologies. While there have been reports of fistulas between the inferior vena cava and the duodenum, we report the first case to our knowledge of a fistula between the jejunum and the inferior vena cava after esophagojejunal anastomosis for recurrent esophageal adenocarcinoma.

Appropriate magnetic resonance imaging techniques for gross tumor volume delineation in external beam radiation therapy of locally advanced cervical cancer

Background Accurate delineation of the gross tumor volumes (GTV) is a prerequisite for precise radiotherapy planning and delivery. Different MRI sequences have different advantages and limitations in their ability to discriminate primary cervical tumor from normal tissue. The purpose of this work is to determine appropriate MRI techniques for GTV delineation for external-beam radiation therapy of locally advanced cervical cancer (LACC). Materials and Methods GTVs were delineated on the MRI, CT, and PET images acquired for 23 LACC patients in treatment positions to obtain GTVs on CT (GTV-CT), on various MRI sequences including T1 (GTV-T1), T2 (GTV-T2), T1 with fat suppression and contrast (GTV-T1F+), DWI-ADC (GTV-ADC) and on PET were generated using the threshold of 40% of maximum SUV (GTV-SUV40%) as well as SUV of 2.5 (GTV-SUV2.5). MRI, CT and PET were registered for comparison. The GTVs defined by MRI were compared using the overlap ratio (OR) and relative volume ratio (RVR). The union of GTV-T2 and GTV-ADC was generated to represent the MRI-based GTV (GTV-MRI). Results The differences between GTV-T2 and other MRI GTVs are significant (P < 0.05). The average ORs for GTV-T1, GTV-T1F+, and GTV-ADC related to GTV-T2 were 86.3%, 81.6%, and 61.6% with the corresponding average RVRs 113.8%, 112.3% and 77.2%, respectively. There is no significant difference between GTV-T1 and GTV-T1F+. GTV-ADC was generally smaller than GTV-T2, however, encompassed suspicious regions that are uncovered in GTV-T2 (up to 16% of GTV-T2) because of different imaging mechanisms. There was significant difference between GTV-MRI, GTV-SUV2.5, GTV-SUV40%, and GTV-CT. On average, GTV-MRI is 18.4% smaller than GTV-CT. Conclusions MRI provides improved visualization of disease over CT or PET for cervical cancer. The GTV from the union of GTV-T2 and GTV-ADC provides a reasonable GTV including tumor region defined anatomically and functionally with MRI and substantially reduces the conventional GTV defined on CT.

Quality Indicators for CT Colonography

Computed tomography (CT) colonography (CTC) provides a minimally invasive examination for the detection of colorectal neoplasia. After the first validation screening trials in early 2000, this technique has begun to transition from academic centers to community practice; however, the lack of reimbursement remains a current barrier. This chapter discusses the recommended, standardized techniques for performing and reporting CTC based on the American College of Radiology (ACR) practice parameters. These guidelines discuss current indications and contraindications, qualifications of interpreting physicians, specification of the examination techniques including low-dose techniques and stool tagging, and communication of results using the CTC reporting and data system (C-RADS) reporting structure for colonic and extra-colonic findings. In addition, this chapter introduces the development of CTC quality metrics, which include both process and outcome measures. The start of the ACR data registry for instituting a cyclical quality improvement program into clinical practice is also discussed.