Rickhesvar P. Mahraj

Indications and approach to surgical resection of lung metastases.

Pulmonary metastasectomy is a curative option for selected patients with cancer spread to the lungs. Complete surgical removal of pulmonary metastases can improve survival and is recommended under certain criteria. Specific issues that require consideration in a multidisciplinary setting when planning pulmonary metastasectomy include: adherence to established indications for resection, the surgical strategy including the use of minimally invasive techniques, pulmonary parenchyma preservation, and the role of lymphadenectomy. J. Surg. Oncol. 2010;102:187–195.

Interbronchoscopist Variability in Endobronchial Path Selection: A Simulation Study

BACKGROUND Endobronchial path selection is important for the bronchoscopic diagnosis of focal lung lesions. Path selection typically involves mentally reconstructing a three-dimensional path by interpreting a stack of two-dimensional (2D) axial plane CT scan sections. The hypotheses of our study about path selection were as follows: (1) bronchoscopists are inaccurate and overly confident when making endobronchial path selections based on 2D CT scan analysis; and (2) path selection accuracy and confidence improve and become better aligned when bronchoscopists employ path-planning methods based on virtual bronchoscopy (VB). METHODS Studies of endobronchial path selection comparing three path-planning methods (ie, the standard 2D CT scan analysis and two new VB-based techniques) were performed. The task was to navigate to discrete lesions located between the third-order and fifth-order bronchi of the right upper and middle lobes. Outcome measures were the cumulative accuracy of making four sequential path selection decisions and self-reported confidence (1, least confident; 5, most confident). Both experienced and inexperienced bronchoscopists participated in the studies. RESULTS In the first study involving a static paper-based tool, the mean (+/- SD) cumulative accuracy was 14 +/- 3% using 2D CT scan analysis (confidence, 3.4 +/- 1.3) and 49 +/- 15% using a VB-based technique (confidence, 4.2 +/- 1.1; p = 0.0001 across all comparisons). For a second study using an interactive computer-based tool, the mean accuracy was 40 +/- 28% using 2D CT scan analysis (confidence, 3.0 +/- 0.3) and 96 +/- 3% using a dynamic VB-based technique (confidence, 4.6 +/- 0.2). Regardless of the experience level of the bronchoscopist, use of the standard 2D CT scan analysis resulted in poor path selection accuracy and misaligned confidence. Use of the VB-based techniques resulted in considerably higher accuracy and better aligned decision confidence. CONCLUSIONS Endobronchial path selection is a source of error in the bronchoscopy workflow. The use of VB-based path-planning techniques significantly improves path selection accuracy over use of the standard 2D CT scan section analysis in this simulation format.

Modern Management of Chylous Leak Following Head and Neck Surgery: A Discussion of Percutaneous Lymphangiography-Guided Cannulation and Embolization of the Thoracic Duct

High-output chylous leak beyond 5 to 7 days of conservative medical treatment should be treated promptly to avoid the risk for nutritional and imunologic depletion. Given the effectiveness and low morbidity of this minimally invasive treatment, this is a reasonable first option before surgical repair of thoracic duct leak not responsive to conservative medical treatment.

The quality of 3D reconstructions from 1.0 and 1.5 pitch helical and conventional CT.

PURPOSE CT data are commonly used to create 3D images. For this purpose, thin and overlapped slices are desirable. Helical (spiral) CT offers the ability to adjust the slice reconstruction interval from 0 to 100%. However, its use in 1.0 and 1.5 pitch helical CT and 3D imaging, especially with respect to surface detail, is relatively untested. METHODS Ten objects selected for their varying size, shape, and density were scanned (fourth generation Picker PQ2000) by contiguous 2,4 and 8 mm conventional and helical sequences. The latter were obtained with a pitch of both 1.0 and 1.5 and were reconstructed into a 3D image with 0-75% overlapping of the reconstructed slices. Each of the 24 different sequences per scanned object was reconstructed into identical sets (projections) of 3D images displayed on color film. The 24 3D image sets for each object were submitted to six blinded radiologists who separately ranked them from best to worst. RESULTS 3D reconstructions obtained from CT scans with a thinner slice thickness, half-field (15 cm FOV), and helical technique were rated as statistically superior. The 1.0 and 1.5 helical sequences obtained with a 4 or 8 mm slice thickness scored statistically better than 3D reconstructions from equivalent conventional scans. Overlapping of the reconstructed helical slices by 25-75% generally improved the quality of the 3D reconstruction. CONCLUSION Helical CT with either a 1.0 or a 1.5 pitch offers the ability to obtain higher quality 3D reconstructions than from comparable conventional CT scans.

Automatic definition of the central-chest lymph-node stations

PurposeLung cancer remains the leading cause of cancer death in the United States. Central to the lung-cancer diagnosis and staging process is the assessment of the central-chest lymph nodes. This assessment requires two steps: (1) examination of the lymph-node stations and identification of diagnostically important nodes in a three-dimensional (3D) multidetector computed tomography (MDCT) chest scan; (2) tissue sampling of the identified nodes. We describe a computer-based system for automatically defining the central-chest lymph-node stations in a 3D MDCT chest scan.MethodsAutomated methods first construct a 3D chest model, consisting of the airway tree, aorta, pulmonary artery, and other anatomical structures. Subsequent automated analysis then defines the 3D regional nodal stations, as specified by the internationally standardized TNM lung-cancer staging system. This analysis involves extracting over 140 pertinent anatomical landmarks from structures contained in the 3D chest model. Next, the physician uses data mining tools within the system to interactively select diagnostically important lymph nodes contained in the regional nodal stations.ResultsResults from a ground-truth database of unlabeled lymph nodes identified in 32 MDCT scans verify the system’s performance. The system automatically defined 3D regional nodal stations that correctly labeled 96% of the database’s lymph nodes, with 93% of the stations correctly labeling 100% of their constituent nodes.ConclusionsThe system accurately defines the regional nodal stations in a given high-resolution 3D MDCT chest scan and eases a physician’s burden for analyzing a given MDCT scan for lymph-node station assessment. It also shows potential as an aid for preplanning lung-cancer staging procedures.

Mandatory Assignment of Modified Wells Score Before CT Angiography for Pulmonary Embolism Fails to Improve Utilization or Percentage of Positive Cases.

OBJECTIVE The objective of our study was to determine the impact of embedding a pretest probability rule that is required during the computerized physician order-entry (CPOE) process on the appropriateness of CT angiography (CTA) of the pulmonary arteries for the diagnosis of pulmonary embolism (PE) in the emergency department (ED). MATERIALS AND METHODS Data were obtained from the electronic medical records of all adults who visited the ED from October 17, 2010, through October 17, 2012 (n = 96,507). The primary outcome was the appropriateness of pulmonary CTA. Logistic regression was used to test whether rates of appropriate use, overuse, and underuse of pulmonary CTA improved significantly after the implementation of the decision support tool when controlling for other patient characteristics. RESULTS Pulmonary CTA was appropriately used in 67.2% of patients with a modified Wells score of ≥ 4, a positive d-dimer test result, or both. CTA was overused in 19.3% of patients and underused in 13.5% of patients. Each additional month after the start of the intervention was associated with a 4-percentage point increase in the odds that the modified Wells score would indicate CTA had been used appropriately (odds ratio [OR] = 1.04; 95% CI, 1.01-1.07) and significantly lowered the odds of overuse of CTA (OR = 0.93; 95% CI, 0.90-0.96) based on the modified Wells score. These changes were not associated with any significant alteration in the level of CTA utilization or the positivity rate. CONCLUSION The addition of a mandatory field in the CPOE record was associated with a significant improvement in the appropriate ordering of pulmonary CTA but did not change the PE positive rate or CTA utilization. It seems likely that physicians gradually inflated the modified Wells scores in spite of the fact that a threshold modified Wells score was not required to perform pulmonary CTA.

Utility of low mA 1.5 pitch helical versus conventional high mA abdominal ct

The objective of this study was to evaluate the utility of a low mA 1.5 pitch helical versus conventional high mA conventional technique in abdominal computed tomography (CT). Twenty-five patients who had both a conventional high mA (> 300) and a 1.5 pitch low mA (80-125) helical CT within 3 months were selected for inclusion in the study. Patients were excluded who had a significant change in pathology between the two studies. The other parameters (injection rate, contrast type and volume, and filming window/level) were constant. The studies were randomized and blinded to five separate experienced readers who graded the studies by a variety of normal anatomical structures and pathological criteria. Overview questions also assessed noise, resolution, contrast, and overall quality. The abdominal wall/retroperitoneum and hiatal hernias were statistically better visualized on the conventional high mA studies. However, for all other normal anatomical and pathological sites, there was equivalent or better visualization on the helical versus the conventional CT examinations. The resolution of the helical studies was graded statistically better than the high mA conventional CT scans as was the amount of noise present on the images. While there was some advantage for conventional high mA CT with respect to contrast enhancement and low contrast sensitivity, these differences were not statistically significant. It appears from the data of this study that a low mA technique in evaluating the abdomen may be a useful option in performing routine abdominal CT. The radiation dose savings to the patient is significant and there appears to be little degradation of image quality using a low mA 1.5 helical versus mA conventional CT technique.

Multiplanar image reconstruction and 3D imaging using a musculoskeletal phantom: conventional versus helical CT.

PURPOSE Our goal was to perform a detailed comparison of the relative performances of helical CT (pitches 1.0, 1.5, and 2.0) and conventional (overlapped and nonoverlapped) CT in detailed 3D and MPR musculoskeletal imaging. METHOD A specially designed bone fragment phantom was imaged with multiple slice thicknesses using conventional (overlapped and nonoverlapped) and helical (varying pitch and slice index) CT. Studies were randomized, blinded, and graded using predetermined criteria by 10 radiologists. Statistical analysis included an assessment of raw image scores, a separate testing using duplicate copies of the conventional images as gold standards, and a multivariate model based upon the results of both scoring systems. RESULTS When assessing raw scores of the images, conventional scans were consistently scored more favorably than helical studies. Decreasing the slice index improved conventional CT studies and helical studies with a pitch of 1.0, but showed no effect on helical studies with a pitch of > 1.0. When using the conventional studies as gold standards, the helical studies were consistently graded as poorer than conventional overlapped and nonoverlapped studies. CONCLUSION For detailed musculoskeletal 3D and MPR work, helical CT may not adequately compare with conventional CT and offers no discernible advantage, particularly for pitches of > 1.0.

Comparison of 1.0-, 1.5-, and 2.0-pitch abdominal helical computed tomography in evaluation of normal structures and pathologic lesions.

RATIONALE AND OBJECTIVES The authors performed a comprehensive prospective clinical trial comparing 1.0-, 1.5-, and 2.0-pitch abdominal helical computed tomography (CT) in the evaluation of normal and pathologic structures/lesions. METHODS Seventy-five consecutive patients were randomized by computer into one of three equal groups: helical CT pitch 1.0, 1.5, and 2.0. The imaging parameters and contrast enhancement of all 75 patients were kept constant. The 75 studies were masked, placed into a randomized order, and evaluated by five separate experienced radiologists who rated visualization of 25 normal structures and up to five pathologic findings per patient using a scale of 1 (not seen) to 5 (very well seen/very sharp margins). RESULTS There were no statistical differences in 1.0- and 1.5-pitch abdominal CT scans when assessing the display of normal and pathologic lesions. In addition, helical pitch 1.0 and 1.5 studies were equivalent for both normal and pathologic structures/lesions, whereas equivalency was not demonstrated for helical pitch 2.0 studies. Overall study assessment questions again found equivalency between helical 1.0- and 1.5-pitch studies. CONCLUSIONS Abdominal CT performed with pitches of 1.0 and 1.5 are equivalent. Because of its advantages, we advocate the routine use of an extended pitch (1.5) in routine abdominal CT. Further studies are required to evaluate the usefulness of the helical 2.0-pitch technique.

Quantitative analysis of the central-chest lymph nodes based on 3D MDCT image data

Lung cancer is the leading cause of cancer death in the United States. In lung-cancer staging, central-chest lymph nodes and associated nodal stations, as observed in three-dimensional (3D) multidetector CT (MDCT) scans, play a vital role. However, little work has been done in relation to lymph nodes, based on MDCT data, due to the complicated phenomena that give rise to them. Using our custom computer-based system for 3D MDCT-based pulmonary lymph-node analysis, we conduct a detailed study of lymph nodes as depicted in 3D MDCT scans. In this work, the Mountain lymph-node stations are automatically defined by the system. These defined stations, in conjunction with our systems image processing and visualization tools, facilitate lymph-node detection, classification, and segmentation. An expert pulmonologist, chest radiologist, and trained technician verified the accuracy of the automatically defined stations and indicated observable lymph nodes. Next, using semi-automatic tools in our system, we defined all indicated nodes. Finally, we performed a global quantitative analysis of the characteristics of the observed nodes and stations. This study drew upon a database of 32 human MDCT chest scans. 320 Mountain-based stations (10 per scan) and 852 pulmonary lymph nodes were defined overall from this database. Based on the numerical results, over 90% of the automatically defined stations were deemed accurate. This paper also presents a detailed summary of central-chest lymph-node characteristics for the first time.