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Evidence-based Practice in Radiology: Steps 3 and 4—Appraise and Apply Diagnostic Radiology Literature¹

¹ From the Department of Radiology, Massachusetts General Hospital, Boston, Mass. Received October 12, 2005; revision requested November 14; revision received December 19; accepted January 19, 2006; final version accepted February 3. Address correspondence to the author, Department of Radiology, St Vincent's University Hospital, Elm Park, Dublin 4, Ireland (e-mail: j.dodd{at}st-vincents.ie).

View larger version (29K): [in this window] [in a new window] [Download PPT slide]   Figure 1a: MeSH terms in a search strategy with PubMed. (a) Clicking Preview/Index tab (arrow a) opens search box in all fields (arrow b). (b) Typing indirect CT venography in the search box and clicking the Index tab (arrow c) opens a list of possible MeSH terms (arrow d). Clicking most appropriate term will highlight it. Different search words can be typed in the search box. Clicking AND and OR tabs (arrow e) adds highlighted MeSH term to the Preview search. Individual searches can then be combined in PICO format. (c) Possible search strategy with MeSH terms. First search with indirect CT venography yields 13 articles (arrow f). Second search with tomography, x ray computed yields 161 371 articles (arrow g). Combining searches yields 10 articles (arrow h). Including only reports in English yields nine articles (arrow i). Such strategies result in more focused and relevant article retrieval.

View larger version (39K): [in this window] [in a new window] [Download PPT slide]   Figure 1b: MeSH terms in a search strategy with PubMed. (a) Clicking Preview/Index tab (arrow a) opens search box in all fields (arrow b). (b) Typing indirect CT venography in the search box and clicking the Index tab (arrow c) opens a list of possible MeSH terms (arrow d). Clicking most appropriate term will highlight it. Different search words can be typed in the search box. Clicking AND and OR tabs (arrow e) adds highlighted MeSH term to the Preview search. Individual searches can then be combined in PICO format. (c) Possible search strategy with MeSH terms. First search with indirect CT venography yields 13 articles (arrow f). Second search with tomography, x ray computed yields 161 371 articles (arrow g). Combining searches yields 10 articles (arrow h). Including only reports in English yields nine articles (arrow i). Such strategies result in more focused and relevant article retrieval.

View larger version (32K): [in this window] [in a new window] [Download PPT slide]   Figure 1c: MeSH terms in a search strategy with PubMed. (a) Clicking Preview/Index tab (arrow a) opens search box in all fields (arrow b). (b) Typing indirect CT venography in the search box and clicking the Index tab (arrow c) opens a list of possible MeSH terms (arrow d). Clicking most appropriate term will highlight it. Different search words can be typed in the search box. Clicking AND and OR tabs (arrow e) adds highlighted MeSH term to the Preview search. Individual searches can then be combined in PICO format. (c) Possible search strategy with MeSH terms. First search with indirect CT venography yields 13 articles (arrow f). Second search with tomography, x ray computed yields 161 371 articles (arrow g). Combining searches yields 10 articles (arrow h). Including only reports in English yields nine articles (arrow i). Such strategies result in more focused and relevant article retrieval.

View larger version (6K): [in this window] [in a new window] [Download PPT slide]   Figure 2: Possible search strategies with the PICO format. The search can be customized to suit different requirements. If time is limited, searching MeSH terms across the row will result in a small retrieval of the most important articles but may miss some relevant ones. If more time is available or a search is required to encompass all important articles on a topic, the search can be widened by inserting more column MeSH terms. This will result in a larger retrieval of important articles but may include some less relevant ones.

View larger version (27K): [in this window] [in a new window] [Download PPT slide]   Figure 3a: Use of GCPs to achieve clinical resolution (solid lines = positive result, dashed lines = negative result). Posttest probability for a positive result is derived by drawing a vertical line up to the solid curved line and then across to the y-axis. Posttest probability for a negative result is derived by drawing a vertical line up to the dotted curved line and then across to the y-axis. (a) GCP for D-dimer test. For a patient with a high pretest probability of PE, the prevalence is 78% (solid arrow). Posttest probability for a positive D-dimer result is 85% (open arrow), which warrants further investigation. (b) This posttest probability is then applied as pretest probability to the GCP for CT pulmonary angiography (solid arrow). If the result is positive, posttest probability is 99% (open arrow) and PE is confirmed. If the result is negative, posttest probability is 30% (curved arrow), which is not low enough to exclude disease (further investigation warranted). (c) This posttest probability is then applied as pretest probability to the GCP for indirect CT venography (solid arrow). If the result is positive, posttest probability of DVT is greater than 72% (open arrow) and diagnosis is confirmed. If the result is negative, posttest probability of DVT is less than 5% (curved arrow) and the diagnosis is excluded.

View larger version (28K): [in this window] [in a new window] [Download PPT slide]   Figure 3b: Use of GCPs to achieve clinical resolution (solid lines = positive result, dashed lines = negative result). Posttest probability for a positive result is derived by drawing a vertical line up to the solid curved line and then across to the y-axis. Posttest probability for a negative result is derived by drawing a vertical line up to the dotted curved line and then across to the y-axis. (a) GCP for D-dimer test. For a patient with a high pretest probability of PE, the prevalence is 78% (solid arrow). Posttest probability for a positive D-dimer result is 85% (open arrow), which warrants further investigation. (b) This posttest probability is then applied as pretest probability to the GCP for CT pulmonary angiography (solid arrow). If the result is positive, posttest probability is 99% (open arrow) and PE is confirmed. If the result is negative, posttest probability is 30% (curved arrow), which is not low enough to exclude disease (further investigation warranted). (c) This posttest probability is then applied as pretest probability to the GCP for indirect CT venography (solid arrow). If the result is positive, posttest probability of DVT is greater than 72% (open arrow) and diagnosis is confirmed. If the result is negative, posttest probability of DVT is less than 5% (curved arrow) and the diagnosis is excluded.

View larger version (27K): [in this window] [in a new window] [Download PPT slide]   Figure 3c: Use of GCPs to achieve clinical resolution (solid lines = positive result, dashed lines = negative result). Posttest probability for a positive result is derived by drawing a vertical line up to the solid curved line and then across to the y-axis. Posttest probability for a negative result is derived by drawing a vertical line up to the dotted curved line and then across to the y-axis. (a) GCP for D-dimer test. For a patient with a high pretest probability of PE, the prevalence is 78% (solid arrow). Posttest probability for a positive D-dimer result is 85% (open arrow), which warrants further investigation. (b) This posttest probability is then applied as pretest probability to the GCP for CT pulmonary angiography (solid arrow). If the result is positive, posttest probability is 99% (open arrow) and PE is confirmed. If the result is negative, posttest probability is 30% (curved arrow), which is not low enough to exclude disease (further investigation warranted). (c) This posttest probability is then applied as pretest probability to the GCP for indirect CT venography (solid arrow). If the result is positive, posttest probability of DVT is greater than 72% (open arrow) and diagnosis is confirmed. If the result is negative, posttest probability of DVT is less than 5% (curved arrow) and the diagnosis is excluded.