Tasneem Lalani

Role of Computed Tomography and Magnetic Resonance Imaging for Deep Venous Thrombosis and Pulmonary Embolism

Abstract—During the 1990s, computed tomography (CT) and magnetic resonance (MR) imaging underwent extensive technological advancement and expanded clinical use in patients with venous thromboembolic disease, particularly with regard to evaluation of the pulmonary vasculature. In many institutions, helical (spiral) CT pulmonary angiography has become the initial imaging study of choice to evaluate patients with suspected pulmonary embolism, supplanting ventilation/perfusion scintigraphy. In addition, CT venography of the pelvis and lower extremities is often incorporated into the CT angiography protocol to identify or exclude concurrent deep venous thrombosis. MR pulmonary angiography and MR venography are second-line diagnostic tools because of their higher cost, limited availability, and other logistical constraints. As the technology improves and becomes more widely available, MR imaging may play a greater role in the evaluation of patients with venous thromboembolic disease.

ACR appropriateness Criteria® right lower quadrant pain - Suspected appendicitis

The most common cause of acute right lower quadrant (RLQ) pain requiring surgery is acute appendicitis (AA). This narratives focus is on imaging procedures in the diagnosis of AA, with consideration of other diseases causing RLQ pain. In general, Computed Tomography (CT) is the most accurate imaging study for evaluating suspected AA and alternative etiologies of RLQ pain. Data favor intravenous contrast use for CT, but the need for enteric contrast when intravenous contrast is used is not strongly favored. Radiation exposure concerns from CT have led to increased investigation in minimizing CT radiation dose while maintaining diagnostic accuracy and in using algorithms with ultrasound as a first imaging examination followed by CT in inconclusive cases. In children, ultrasound is the preferred initial examination, as it is nearly as accurate as CT for the diagnosis of AA in this population and without ionizing radiation exposure. In pregnant women, ultrasound is preferred initially with MRI as a second imaging examination in inconclusive cases, which is the majority.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Computed tomography diagnosis of ischemia and complete obstruction in small bowel obstruction: A systematic review

This review was designed to describe the diagnostic performance of computed tomography (CT) in assessing bowel ischemia and complete obstruction in small bowel obstruction (SBO). AMEDLINEsearch (1966-2004) identi.ed 15 studies dealing with the CT diagnosis of ischemia and complete obstruction in SBO. Ischemia was defined by operative findings, and complete obstruction was defined by enteroclysis or operative findings. Aggregated sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated. Eleven of 15 studies reported on the CT diagnosis of ischemia in SBO based on 743 patients. The aggregated performance characteristics of CTfor ischemia in SBO were sensitivity of 83% (range, 63–100%), specificity of 92% (range, 61–100%), PPV of 79% (range, 69–100%), and NPV of 93% (range, 33.3-100%). Seven of 15 studies evaluated the CT classification of complete obstruction based on 408 patients. The aggregated performance characteristics of CT for complete obstruction were sensitivity of 92% (range, 81–100%), specificity of 93% (range, 68–100%), PPV of 91% (range, 84–100%), and NPV of 93% (range, 76–100%). This review demonstrates the high sensitivity of CT for ischemia in the setting of SBO and suggests that a CT scan finding of partial SBO is likely to refiect a clinical condition that will resolve without surgical intervention.

ACR appropriateness criteria® pretreatment staging of colorectal cancer

Because virtually all patients with colonic cancer will undergo some form of surgical therapy, the role of preoperative imaging is directed at determining the presence or absence of synchronous carcinomas or adenomas and local or distant metastases. In contrast, preoperative staging for rectal carcinoma has significant therapeutic implications and will direct the use of radiation therapy, surgical excision, or chemotherapy. CT of the chest, abdomen, and pelvis is recommended for the initial evaluation for the preoperative assessment of patients with colorectal carcinoma. Although the overall accuracy of CT varies directly with the stage of colorectal carcinoma, CT can accurately assess the presence of metastatic disease. MRI using endorectal coils can accurately assess the depth of bowel wall penetration of rectal carcinomas. Phased-array coils provide additional information about lymph node involvement. Adding diffusion-weighted imaging to conventional MRI yields better diagnostic accuracy than conventional MRI alone. Transrectal ultrasound can distinguish layers within the rectal wall and provides accurate assessment of the depth of tumor penetration and perirectal spread, and PET and PET/CT have been shown to alter therapy in almost one-third of patients with advanced primary rectal cancer. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Relationship between Non-Small Cell Lung Cancer Fluorodeoxyglucose Uptake at Positron Emission Tomography and Surgical Stage with Relevance to Patient Prognosis

Purpose: Because the tumor stage is the most significant prognostic factor for non-small cell lung cancer (NSCLC) and given that NSCLC [18F]fluorodeoxyglucose (18F-FDG) uptake appears to have prognostic significance, we examined the relationship between NSCLC 18F-FDG uptake and surgical stage. Experimental Design: One hundred seventy-eight patients with a proven diagnosis of NSCLC were enrolled, then imaged with 18F-FDG positron emission tomography and their disease thoroughly staged. Primary tumor size at computed tomography and 18F-FDG uptake were compared to overall tumor stage and to T, N, and M stage descriptors. Tumor uptake was quantitated by maximum pixel-standardized uptake value (maxSUV) and then partial volume corrected for lesion size using recovery coefficients. Results: A significant difference in tumor size was associated with tumors of different TNM stage, T status, N status, or M status. Similarly, the primary tumor maxSUV was significantly associated with TNM stage, T status, and M status. However, we observed no significant difference in the partial-volume-corrected tumor maxSUV for different stages; different T, N, or M descriptors; tumors without evidence of spread (N0M0) versus tumors with nodal spread (N1,2,3M0); or tumors without spread (N0M0) versus all others. Conclusions: We found an association between tumor stage and 18F-FDG maxSUV, but this relationship disappeared after correction of tumor uptake for lesion size. Therefore, if partial-volume-corrected 18F-FDG uptake is prognostic of NSCLC outcome, it is not on the basis of a relationship with tumor stage but through a different mechanism.

Dandy-Walker malformation complex: correlation between ultrasonographic diagnosis and postmortem neuropathology.

OBJECTIVE: This autopsy-based study was designed to evaluate sonographic and neuropathologic findings of fetuses diagnosed prenatally with Dandy-Walker malformation complex. METHODS: The retrospective study encompassed a series of 44 autopsy cases from 2 tertiary referral centers with a prenatal ultrasound diagnosis of Dandy-Walker malformation complex between 1995 and 2003. Ultrasound and pathology data from the cases and from age-matched controls were reviewed in a blinded manner. An unequivocal diagnosis of Dandy-Walker malformation complex from ultrasonography or pathology archival images required significant hypoplasia or aplasia of the cerebellar vermis. RESULTS: Neuropathologic examination failed to confirm the prenatal diagnosis of Dandy-Walker malformation complex in 59% (26/44, 95% confidence interval [CI] 44–72) of the cases. After standardized reevaluation of high quality archival sonograms and pathology images, concordance remained poor at 55% (6/11 cases, 95% CI 28–79). Sonographic features that favored concordance included marked enlargement of the cisterna magna (≥ 10 mm), complete aplasia of the vermis, and a trapezoid-shaped gap between the cerebellar hemispheres. This latter finding contrasted with a keyhole-shaped gap in fetuses with no cerebellar neuropathology. CONCLUSION: Correlation between a prenatal ultrasound diagnosis of Dandy-Walker malformation complex and autopsy neuropathology findings is poor. Unequivocal prenatal sonographic diagnosis of Dandy-Walker malformation complex should be reserved for cases with the classic findings of Dandy-Walker malformation, including enlargement of the cisterna magna, aplasia of the vermis, and a trapezoid-shaped, rather than keyhole-shaped, interhemispheric gap. LEVEL OF EVIDENCE: III

ACR Appropriateness Criteria® on Crohn's Disease

In the past decade, new therapeutic agents have been developed that permit gastroenterologists to treat virtually all forms of Crohns disease. The success of these treatments depends on an accurate diagnosis of the nature and extent of disease. Fortunately, radiologists now possess a powerful arsenal of imaging techniques to guide the choice of therapy. This article discusses the usefulness of both traditional and newer imaging techniques in the management of Crohns disease and its various clinical presentations.

ACR Appropriateness Criteria ® on Colorectal Cancer Screening

Colorectal cancer remains one of the most common causes of cancer death in this country. This malignancy is ideally suited for screening because the detection and removal of the precursor adenomatous polyp can prevent most colorectal cancers from ever forming. The choice of a test for screening involves consideration of various individual parameters, including patient age and the presence of risk factors for the development of colorectal cancer. Computed tomographic colonography (CTC) has emerged as the leading imaging technique for colorectal cancer screening in average-risk individuals on the basis of the evidence presented in this paper. The double-contrast barium enema is an alternative imaging test that is appropriate particularly when CTC is not available. In 2008, the American Cancer Society guideline for colorectal cancer screening was revised jointly with the US Multi-Society Task Force on Colorectal Cancer and the ACR to include CTC every 5 years as an option for average-risk individuals. Computed tomographic colonography is also the preferred test for colon evaluation after an incomplete colonoscopy. Imaging tests including CTC and the double-contrast barium enema are usually not indicated for colorectal cancer screening in high-risk patients with polyposis syndromes or inflammatory bowel disease. This paper presents the new colorectal cancer imaging test ratings and is the result of evidence-based consensus by the ACR Appropriateness Criteria Expert Panel on Gastrointestinal Imaging.

ACR Appropriateness Criteria Crohn Disease

Crohn disease is a chronic inflammatory disorder involving the gastrointestinal tract, characterized by episodic flares and times of remission. Underlying structural damage occurs progressively, with recurrent bouts of inflammation. The diagnosis and management of this disease process is dependent on several clinical, laboratory, imaging, endoscopic, and histologic factors. In recent years, with the maturation of CT enterography, and MR enterography, imaging has played an increasingly important role in relation to Crohn Disease. In addition to these specialized examination modalities, ultrasound and routine CT have potential uses. Fluoroscopy, radiography, and nuclear medicine may be less beneficial depending on the clinical scenario. The imaging modality best suited to evaluating this disease may change, depending on the target population, severity of presentation, and specific clinical situation. This document presents seven clinical scenarios (variants) in both the adult and pediatric populations and rates the appropriateness of the available imaging options. They are summarized in a consolidated table, and the underlying rationale and supporting literature are presented in the accompanying narrative. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria® Colorectal Cancer Screening

Colorectal cancer is the third leading cause of cancer deaths in the United States. Most colorectal cancers can be prevented by detecting and removing the precursor adenomatous polyp. Individual risk factors for the development of colorectal cancer will influence the particular choice of screening tool. CT colonography (CTC) is the primary imaging test for colorectal cancer screening in average-risk individuals, whereas the double-contrast barium enema (DCBE) is now considered to be a test that may be appropriate, particularly in settings where CTC is unavailable. Single-contrast barium enema has a lower performance profile and is indicated for screening only when CTC and DCBE are not available. CTC is also the preferred test for colon evaluation following an incomplete colonoscopy. Imaging tests including CTC and DCBE are not indicated for colorectal cancer screening in high-risk patients with polyposis syndromes or inflammatory bowel disease. This paper presents the updated colorectal cancer imaging test ratings and is the result of evidence-based consensus by the ACR Appropriateness Criteria Expert Panel on Gastrointestinal Imaging. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.