Noncontrast techniques such as DWI have been used to evaluate evidence for CD. There is growing literature examining its promise in detecting active disease versus quiescent disease for complication evaluation and disease monitoring, although many of the studies involve DWI in the context of enterography technique [77]. One study without enterography technique [48] reported a sensitivity of 49% to 82% and specificity of 85% to 93% for DWI, although lower specificities have been reported at meta- analysis [78]. Overall, DWI appears to have moderate sensitivity but low specificity, leading to increased false positives for disease activity [77]. Thus, the current consensus is that noncontrast only techniques such as DWI can Crohn Disease be done, but there is likely improved performance with the information gained from post IV contrast series. This reason, as well as the lack of a bowel distention optimization protocol, makes standard MRI without IV contrast less useful in this clinical variant. US Abdomen and Pelvis Transabdominal US can be effective option in CD [84,85]. However, in this variant, it may not be optimal given that areas of the abdomen may not be assessed because of shadowing bowel. However, there is emerging literature that US may be useful in therapy monitoring of CD patients [114,115]. In addition, contrast-enhanced US may be helpful in distinguishing between inflammatory and fibrotic disease [95]. Patient factors such as obesity and guarding may not allow adequate compression with the US probe or large amounts of shadowing gas may obscure bowel, preventing an optimal examination. Location also affects diagnosis in which higher sensitivities for terminal ileal involvement are seen compared to more proximal small bowel [87]. False positive diagnoses of abscesses are more likely at US [97]. Radiography Abdomen Radiographs of the abdomen are limited in the evaluation for CD.
Crohn Disease. Noncontrast techniques such as DWI have been used to evaluate evidence for CD. There is growing literature examining its promise in detecting active disease versus quiescent disease for complication evaluation and disease monitoring, although many of the studies involve DWI in the context of enterography technique [77]. One study without enterography technique [48] reported a sensitivity of 49% to 82% and specificity of 85% to 93% for DWI, although lower specificities have been reported at meta- analysis [78]. Overall, DWI appears to have moderate sensitivity but low specificity, leading to increased false positives for disease activity [77]. Thus, the current consensus is that noncontrast only techniques such as DWI can Crohn Disease be done, but there is likely improved performance with the information gained from post IV contrast series. This reason, as well as the lack of a bowel distention optimization protocol, makes standard MRI without IV contrast less useful in this clinical variant. US Abdomen and Pelvis Transabdominal US can be effective option in CD [84,85]. However, in this variant, it may not be optimal given that areas of the abdomen may not be assessed because of shadowing bowel. However, there is emerging literature that US may be useful in therapy monitoring of CD patients [114,115]. In addition, contrast-enhanced US may be helpful in distinguishing between inflammatory and fibrotic disease [95]. Patient factors such as obesity and guarding may not allow adequate compression with the US probe or large amounts of shadowing gas may obscure bowel, preventing an optimal examination. Location also affects diagnosis in which higher sensitivities for terminal ileal involvement are seen compared to more proximal small bowel [87]. False positive diagnoses of abscesses are more likely at US [97]. Radiography Abdomen Radiographs of the abdomen are limited in the evaluation for CD.