Tab. 1.
Indications for a given imaging modality as per the category of abdominal pathology
| Ultrasound | CEUS | CT | MRI | |
|---|---|---|---|---|
| Abdominal emergencies (non-traumatic) | First-line imaging technique | Technique of choice if US is inconclusive | Can be used, as an alternative to CT in selected cases (e.g. suspicion of acute appendicitis), especially in children or young patients | |
| Abdominal emergencies (traumatic) | First-line imaging technique in low-energy trauma limited to the abdomen; FAST technique for the detection of hemoperitoneum, particularly useful in unstable patients | Improves the sensitivity of US in detecting parenchymal trauma and active hemorrhage | First-line imaging technique in high-energy trauma | |
| Jaundice | First-line imaging technique. Confirms the obstructive cause of jaundice by showing bile duct dilatation | Can be used as a substitute ifMRI is not available. Low sensitivity for bile duct calculi | Technique of choice if US is inconclusive | |
| Urinary symptoms | First-line imaging technique. Confirms the presence of hydronephrosis | Technique of choice for the diagnosis of renal or ureteral calculi | ||
| Palpable abnormality (abdominal mass or organomegaly) | First-line imaging technique for confirming hepato- or splenomegaly. Can be used to exclude an abdominal mass in order to avoid excessive irradiation by CT | Technique of choice for characterizing an abdominal mass discovered by US or clinical examination. | Can be used as a substitute for CT in selected cases. Technique of choice for characterizing pelvic masses. | |
| Elevated liver enzymes | Imaging technique of choice for diagnosing and characterization of diffuse liver disease | Complementary to US; can be used to quantify diffuse liver disease | ||
| Staging and evaluation of already known oncologic disease | Used in the characterization of indeterminate liver lesions seen on CT | Technique of choice, both for baseline imaging and also for follow-up | Used complementary to CT for the characterization of indeterminate lesions, particularly focal liver lesions | |
| Evaluation of suspected congenital abnormalities | First-line imaging technique, both ante-and postnatal | Used in the characterization of complex urinary tract malformations | Better characterization of abnormalities, incompletely evaluated by US. Can be used both ante-and postnatally | |
| Pre- and post-transplantation evaluation | Can be used in the follow-up of transplanted patients in order to avoid excessive irradiation | Improves US sensitivity in depicting vascular complications in the transplanted patient | Technique of choice due to its better suitability in assessing vascular structures | |
| Guiding of interventional procedures | Technique of choice | Can be used to improve US-guided procedures (e.g. avoid the punction of the necrotized area in necrotic tumors) | Second-line technique in cases when UScannotguide the procedure (lesion not identifiable by US, or vascular/digestive interpositions) | |
| Evaluation of peritoneal and retroperitoneal fluid | First-line imaging technique, both ante-and postnatal | Used in the characterization of complex urinary tract malformations | Better characterization of abnormalities, incompletely evaluated by US. Can be used both ante-and postnatally | |
| Postoperative complications | First-line imaging technique | Can be used for better characterization of abnormalities, such as collections or free fluid, discovered by ultrasound, for characterization of inconclusive US findings or in cases of discrepancy between US and the clinical status of the patient | ||
| Follow-up of liver cirrhosis and characterization of liver nodules in the cirrhotic liver | First-line imaging technique, used for the detection of liver nodules on the cirrhotic liver | Characterization of liver nodules discovered by routine US | Characterization of liver nodules discovered by routine US | Characterization of liver nodules discovered by routine US |
| Evaluation of abdominal vessels | Can be used in the follow-up of ectatic abdominal aorta to avoid overirradiation | Technique of choice for the initial characterization and follow-up of abdominal aortic aneurysms | ||
| Characterization of incidentally discovered focal liver lesions | In experienced centers, it can represent the first-line imaging technique for characterization of focal liver lesions | Substitute to MRI in cases when MRI is not available or not feasible | Technique of choice in cases of inconclusive CEUS findings | |
| Liver infections | First-line imaging technique for the detection of liver abscess or hydatid cyst | It can be used, as a second-line imaging technique for the differentiation between infectious lesions and other focal liver lesions | It can be used, as a second-line imaging technique for the differentiation between infectious lesions and other focal liver lesions | It can be used, as a second-line imaging technique for the differentiation between infectious lesions and other focal liver lesions |
| Evaluation of pancreatic tumors | Endoscopic US can be used complementary to CT as a second-line technique to evaluate inconclusive CT findings | Technique of choice for staging pancreatic tumors | It can be used to clarify inconclusive CT findings, particularly in the case of cystic pancreatic tumors | |
| Inflammatory bowel disease | US and MRI have complementary roles in the initial evaluation and in the subsequent follow-up of patients with inflammatory bowel disease | CTcan be used as a substitute for MRI due to its better spatial resolution; its usage should be limited to cases when MRI is not available or not feasible due to the fact that patients with IBD are in most cases adolescents or young adults and it is recommended to avoid irradiation in those patients | US and MRI have complementary roles in the initial evaluation and in the subsequent follow-up of patients with inflammatory bowel disease | |
| Local staging of rectal tumors | Endoscopic US can be used complementary to MRI for the characterization of rectal wall invasion (differentiation between T1/T2/T3a tumors) | Technique of choice for local staging of rectal cancer; evaluation for distant metastases is done by CT as for every abdominal or pelvic malignancy | ||
| Perianal fistulas | Technique of choice for the evaluation of perianal fistulas |