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Everything you need to know about Computed Tomography (CT) & CT Scanning

3D and Workflow: Misdiagnosis and Use of 3D Imaging Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ 3D and Workflow ❯ Misdiagnosis and Use of 3D Imaging

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  • Errors on CT of the Body in the ER Setting
    Poor patient prep
    Poor selection of scan protocol
    Lack of interaction of the technologists and the Radiologist.
    Mis-reads of CT scans (false positive or negative)
  • “Another common situation that may produce errors is the inadequate flow of intravenously injected contrast material. Consequently, adequate catheter access and a flow rate of intravenous contrast of 3.5 ml/second higher should be established, as such conditions will help for the correct identification of vascular injuries. In fact, in polytrauma patients, the correct characterization of such injuries is crucial; the site of vascular contrast extravasation (blush) must be identified and the nature of the extravasation must be characterized.”
    Errors in imaging patients in the emergency setting.
    Pinto A, Reginelli A, Pinto F et al.
    Br J Radiol 2016; 89: 20150914.
  • “Injuries of the diaphragm are not common and represent 5% of missed injuries, half of which are not recognized in the first 24 h after the traumatic event. Diagnosis of the injured diaphragm is particularly difficult, resulting in a late diagnosis, and some studies have reported that the sensitivity CT examination for the diagnosis of fractures of the diaphragm is relatively low (50–73%).”
    Errors in imaging patients in the emergency setting.
    Pinto A, Reginelli A, Pinto F et al.
    Br J Radiol 2016; 89: 20150914.
  • “Technical parameters of CT scans (region of interest, use of a contrast agent and scanning timing) differ according to the clinical suspected diseases, and if performed under in- appropriate conditions, CT images will not provide appropriate information for diagnosis. Thus, to avoid missing positive CT findings, in addition to careful readings, radiologists need to obtain such patient information from clinicians.”
    Errors in imaging patients in the emergency setting.
    Pinto A, Reginelli A, Pinto F et al.
    Br J Radiol 2016; 89: 20150914.
  • “Liver metastases without sufficient contrast enhancement, those in patients with hepatic steatosis, those in subcapsular locations, and those found at examinations for indications other than to assess for tumors were significantly more likely to be overlooked.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “CT is often used to image not only liver metastases but also a wide range of potential sites of extrahepatic disease during the same examination. Consequently, CT is recommended as part of the initial workup of many tumors and subsequent surveillance for metastatic disease after a diagnosis of primary cancer. During CT interpretation, however, liver metastases in the early stages are occasionally overlooked, and the best chance to treat them is lost.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “There are many types of error in diagnostic radiology, but two broad categories have been identified: perceptual errors (those in which an important abnormality is missed on images) and cognitive errors (those in which the abnormality is visually detected but the meaning or importance of the finding is not correctly understood or appreciated). Perceptual errors are also thought to be the main cause of overlooked liver metastases, especially in patients with known malignant tumors.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “We investigated the imaging character- istics of liver metastases overlooked at contrast-enhanced CT. The results showed that missed lesions were significantly associated with lower CNR, subcapsular location, hepatic steatosis, and examination indication other than assessment of malignant tumors.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “In this study, missed lesions were significantly associated with subcapsular location. A prior study showed that a common cause of perceptual errors is the location of a finding, and radiologists tend to overlook findings in the periphery of the locations of interest. We may misinterpret subcapsular liver metastases as soft tissue outside the liver because of the thin boundary with background liver. We also may have a tendency to unconsciously focus on the central area of the liver.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “Missed lesions were significantly associat- ed with examinations performed for indica- tions other than survey of malignant tumors. We may not spend more time and energy to find liver metastases after making the first finding during the examination. This is known as satisfaction of search, the second most common type of diagnostic error.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “The causes of overlooking metastases, like the causes of missing other lesions, are mul- tifactorial, extremely subjective, and difficult to analyze. They cannot be separated from the interpretation environment of radiologists, such as fatigue, anxiety, and lack of concentration. Knowledge of the specific imaging characteristics that we describe may help radiologists detect liver metastases correctly.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • “In summary, we performed a retrospective study to investigate the imaging characteristics of liver metastases overlooked at contrast-enhanced CT. We conclude that liver metastases without sufficient contrast, those in a subcapsular location, those in patients with hepatic steatosis, and those on scans ob- tained for indications other than survey of malignant tumors may have a tendency to be overlooked. We should keep these points in mind when looking for liver metastases at contrast-enhanced CT.”
    Imaging Characteristics of Liver Metastases Overlooked at Contrast-Enhanced CT
    Naka H et al.
    AJR 2019; 212:782–787
  • " 3D imaging has matured to become routinely applied in clinical practice. However, despite progress and refinements in organ or structure segmentation, there is a long way to go to obtain fully automatic segmentation of any organ. Although 3D images of bony structures can be obtained by a single mouse click, 3D images of other organs are still time demanding and often require manual adjustments for exact delineation of organs and pathological structures."
    Three-dimensional imaging: Past, present and future
    Fishman EK, Bluemke DA, Soyer P
    Diagnostic and Interventional Imaging
    Volume 97, Issue 3, March 2016, Pages 283-285
  • "With advances in computer hardware especially with advanced graphics processing unit development, the capabilities of low cost post-processing will continue to evolve and 3D imaging has a promising future."
    Three-dimensional imaging: Past, present and future
    Fishman EK, Bluemke DA, Soyer P
    Diagnostic and Interventional Imaging
    Volume 97, Issue 3, March 2016, Pages 283-285
  • "Maximum intensity projection (MIP) imaging involves selecting the highest attenuation voxels in a data set and then incorporating these high-attenuation voxels into a 2D image. MIP imaging is optimized for evaluating vascular anatomy, while volume rendering allows for optimal visualization of the soft tissues, bony structures, and vasculature in a single image and is the most appropriate 3D technique for demonstrating complex relationships between vessels and adjacent organs."
    Three-dimensional imaging: Past, present and future
    Fishman EK, Bluemke DA, Soyer P
    Diagnostic and Interventional Imaging
    Volume 97, Issue 3, March 2016, Pages 283-285
  • "Volume rendering requires a more complex computer algorithm. It analyzes the content of each voxel within a data set, assigns a specific color and transparency based on its underlying attenuation, and subsequently presents the data in a 3D display. 3D imaging is now perceived as a valuable adjunct to 2D images for preoperative evaluation of myriad surgical procedures."
    Three-dimensional imaging: Past, present and future
    Fishman EK, Bluemke DA, Soyer P
    Diagnostic and Interventional Imaging
    Volume 97, Issue 3, March 2016, Pages 283-285
  • 1987 and what has changed?
     
  • “Axial and coronal reformations of 64-section multidetector row CT have equal sensitivity and specificity for the diagnosis of acute abdominal pathology. However, coronal reformations improved the diagnostic confidence for all readers but most significantly for the least experienced. Therefore, radiology departments with residents should consider routinely generating coronal images in patients with acute abdominal pain.”
    Acute abdomen: Added diagnostic value of coronal reformations with 64-slice multidetector row computed tomography.
    Zangos S et al.
    Acad Radiol. 2007 Jan;14(1):19-27.
  • “For the most inexperienced reader, the coronal reformations were helpful in 95% of cases, while for the most experienced reader, the coronal reformations were helpful in 35% of the cases. The coronal images were deemed helpful in an average of 62.3% of the cases for the four readers. However, diagnosing subtle pathology in the abdominal wall was difficult on coronal reformations alone. Overall, coronal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal abdominal structures and in the diagnosis of abdominal pathology.”
    Acute abdomen: Added diagnostic value of coronal reformations with 64-slice multidetector row computed tomography.
    Zangos S et al.
    Acad Radiol. 2007 Jan;14(1):19-27.
  • “Acute traumatic intracranial abnormality was detected on axial scans in 45 patients. Subtle findings were confirmed on coronal and sagittal CT reformations in ten cases, and these were undetected initially on axial CT. Coronal and sagittal reformations confirmed subtle findings in 18.2% (10/55) of the cases (P = 0.001). Indeterminate neuroimaging findings confirmed by coronal and sagittal CT head reformations include tentorial and interhemispheric fissure subdural hemorrhage, subarachnoid hemorrhage, and inferior frontal and temporal lobe contusions. Coronal and sagittal CT head reformations improve the sensitivity and diagnostic confidence in the clinical setting of acute trauma. Overall, coronal and sagittal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal structures and in the diagnosis of acute abnormality.”
    Subtle pathology detection with multidetector row coronal and sagittal CT reformations in acute head trauma.
    Emerg Radiol. 2010 Mar;17(2):97-102
    Zacharia TT, Nguyen DT.
  • “Coronal and sagittal CT head reformations improve the sensitivity and diagnostic confidence in the clinical setting of acute trauma. Overall, coronal and sagittal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal structures and in the diagnosis of acute abnormality.”
    Subtle pathology detection with multidetector row coronal and sagittal CT reformations in acute head trauma.
    Emerg Radiol. 2010 Mar;17(2):97-102
    Zacharia TT, Nguyen DT.
  • “Sixteen-section multi-detector row CT transverse and coronal reformations are equally sensitive and specific for diagnosis of appendicitis. Coronal reformations improve confidence in visualization of appendix (whether diseased or normal) and in diagnosis or exclusion of appendicitis.”
    Acute appendicitis: added diagnostic value of coronal reformations from isotropic voxels at multi-detector row CT.
    Paulson EK et al.
    Radiology. 2005 Jun;235(3):879-85.
  • “Mean sensitivity and specificity for all three readers together were 96% and 95% for transverse reformations alone and 95% and 94% for combined transverse and coronal reformations (not significant), respectively. Visualization rates for portion or all of appendix were higher for combined transverse and coronal reformations than for transverse reformations alone (higher mean confidence scores: 0.23 higher [P < .009] and 0.51 higher [P < .001], respectively). In patients without appendicitis, transverse and coronal reformations together enhanced confidence in exclusion of wall thickening, distention, and fluid (lower confidence scores: 0.21 lower [P < .001], 0.17 lower [P < .01], 1.00 lower [P < .001], respectively). Combined transverse and coronal reformations enhanced confidence in identification of appendix in mean of 57 patients. Combined transverse and coronal scans helped exclude appendicitis in mean of 38 patients and aided diagnosis of it in 15.”
    Acute appendicitis: added diagnostic value of coronal reformations from isotropic voxels at multi-detector row CT.
    Paulson EK et al.
    Radiology. 2005 Jun;235(3):879-85.
  • “ In patients without appendicitis, transverse and coronal reformations together enhanced confidence in exclusion of wall thickening, distention, and fluid (lower confidence scores: 0.21 lower [P < .001], 0.17 lower [P < .01], 1.00 lower [P < .001], respectively). Combined transverse and coronal reformations enhanced confidence in identification of appendix in mean of 57 patients. Combined transverse and coronal scans helped exclude appendicitis in mean of 38 patients and aided diagnosis of it in 15.”
    Acute appendicitis: added diagnostic value of coronal reformations from isotropic voxels at multi-detector row CT.
    Paulson EK et al.
    Radiology. 2005 Jun;235(3):879-85.
  • “ Acute appendicitis is the most common cause of abdominal pain requiring urgent surgery in the United States. The clinical diagnosis can be difficult in patients with atypical presentations and, over the past several decades, computed tomography (CT) has been increasingly utilized to improve diagnostic accuracy. Helical CT has proven to be an excellent tool in the work-up of acute abdominal pain with a diagnostic accuracy for acute appendicitis of 93-99%. However, occasionally there are equivocal or false positive or negative cases, often due to non-visualization of the appendix. The development of multi-detector row CT and recent advancements in reconstruction software has allowed rapid, high-resolution imaging of the entire abdomen and pelvis resulting in multiplanar reformations (MPR) with a spatial resolution similar to that of the axial plane. This article reviews the utility of CT in suspected acute appendicitis and the potential added diagnostic value of coronal reformations in confirming or excluding the diagnosis.”
  • “Helical CT has proven to be an excellent tool in the work-up of acute abdominal pain with a diagnostic accuracy for acute appendicitis of 93-99%. However, occasionally there are equivocal or false positive or negative cases, often due to non-visualization of the appendix. The development of multi-detector row CT and recent advancements in reconstruction software has allowed rapid, high-resolution imaging of the entire abdomen and pelvis resulting in multiplanar reformations (MPR) with a spatial resolution similar to that of the axial plane. This article reviews the utility of CT in suspected acute appendicitis and the potential added diagnostic value of coronal reformations in confirming or excluding the diagnosis.”
    MDCT of acute appendicitis: value of coronal reformations.
    Neville AM, Paulson EK
    Abdom Imaging. 2009 Jan-Feb;34(1):42-8.
  • “Advancements in MDCT technology and improvements in 3D software have significantly improved our ability to detect and characterize pancreatic pathologic disorders. However, we consistently see avoidable errors made by interpreting CT radiologists. These include failure to identify a mass, misdiagnosis of extrapancreatic structures as pancreatic neoplasms, and mischaracterization of a lesion as malignant when it is in fact benign.”
    MDCT of the Abdomen: Common Misdiagnosis at a Busy Academic Center
    Horton KM, Johnson PT, Fishman EK
    AJR 2010;194:660-667s
  • “All suspected pancreatic lesions should be evaluated using thin collimation arterial and portal venous phase acquisitions, and interpretation requires review with interactive multiplanar reconstruction and 3D rendering, even if no lesion is detected on the axial scans. The 3D imaging is especially useful in distinguishing pancreatic from peripancreatic structures and for detecting subtle lesions, as well as for accurate staging of vascular encasement.”
    MDCT of the Abdomen: Common Misdiagnosis at a Busy Academic Center
    Horton KM, Johnson PT, Fishman EK
    AJR 2010;194:660-667s
  • 3D Imaging
    Common Misdiagnosis in Body CT: Solutions
     - The need to be aware of pitfalls in general helps you avoid those pitfalls
     - Moving to routine review of non-axial plane imaging. Even a cursory look at coronal and sagittal images will be useful
     - New workflow patterns with next generation workflow and software that incorporate “advanced visualization tools” and make them “standard visualization tools”.
  • Common Misdiagnosis in Body CT
     - Unsuspected pulmonary embolism
     - Gastric tumors especially toward the fundus
     - Etiology of biliary tract obstruction (stone)
     - Pancreatic tumor detection
     - Renal tumors especially in the upper/lower pole
     - Small bowel tumor detection
     - Mesenteric vascular pathology
     - Musculoskeletal pathology
  • “ At our busy academic institution, we have noticed repeated examples of certain misdiagnosis, even by experienced abdominal imagers, both in our own department and at outside institutions. This is likely related to many factors. Discussed here are a variety of common diagnostic errors on body CT examinations.”

    MDCT of the Abdomen: Common Misdiagnosis at a Busy Academic Center
    Horton KM, Johnson PT, Fishman EK
    AJR 2010; 194:660-667
  • “ For each diagnostic error, we explore the reasons for the misdiagnosis and provide experience based advise to avoid these mistakes.”

    MDCT of the Abdomen: Common Misdiagnosis at a Busy Academic Center
    Horton KM, Johnson PT, Fishman EK
    AJR 2010; 194:660-667
  • “ At some point, multiplanar reconstructions will become the standard of care, as opposed to a supplemental display technique.”

    MDCT of the Abdomen: Common Misdiagnosis at a Busy Academic Center
    Horton KM, Johnson PT, Fishman EK
    AJR 2010; 194:660-667
  • 3D Imaging

    "Isotropic scanning of the abdomen and pelvis allows creation of reformats with similar image quality as similar slice thickness axial source images. These reformats are of sufficient quality to form the basis of clinical interpretation."

    Isotropic CT Examination of Abdomen and Pelvis: Diagnostic Quality of Reformat
    Sandrasegaran K et al.
    Acad Radiol 2006; 13:1338-1343
  • "These reformats may be used as the basis of routine image interpretation, changing the long established tradition of using only axial images for reporting."

    Isotropic CT Examination of Abdomen and Pelvis: Diagnostic Quality of Reformat
    Sandrasegaran K et al.
    Acad Radiol 2006; 13:1338-1343
  • "The sensitivity for diagnosing appendicitis based on the coronal images alone was 96%, the specificity was 100% and the accuracy was 98%. Coronal reformations decreased the number of images by 19%. CT diagnosis of appendicitis based on the coronal images is accurate."

    MDCT diagnosis of appendicitis using only coronal reformations
    Yaghmai V et al.
    Emerg Radiol (2007) 14:167-172 (4MDCT Scanner)
  • "The sensitivity for diagnosing appendicitis based on the coronal images alone was 96%, the specificity was 100% and the accuracy was 98%. CT diagnosis of appendicitis based on the coronal images is accurate."

    MDCT diagnosis of appendicitis using only coronal reformations
    Yaghmai V et al.
    Emerg Radiol (2007) 14:167-172 (4MDCT Scanner)
  • 3D technology :

    "Unsuspected mesenteric arterial abnormality may elude diagnosis when axial MDCT sections are interpreted without 3D renderings."

    Unsuspected Mesenteric Arterial Abnormality: Comparison of MDCT Axial Sections to Interactive 3D Rendering
    Chen JK, Johnson PT, Horton KM, Fishman EK
    AJR 2007;189:807-813
  • "In the era of isotropic data, perhaps the new standard of care will be to review all MDCT data sets in 3D mode to exclude any unsuspected vascular abnormality."

    Unsuspected Mesenteric Arterial Abnormality: Comparison of MDCT Axial Sections to Interactive 3D Rendering
    Chen JK, Johnson PT, Horton KM, Fishman EK
    AJR 2007;189:807-813
© 1999-2019 Elliot K. Fishman, MD, FACR. All rights reserved.