Clinical correlations of small bowel CT and contrast radiology findings in Crohn's disease.

BACKGROUNDS AND OBJECTIVE: Aim of the present study was to evaluate the clinical correlates of small bowel CT patterns in patients with Crohn's disease (CD), as compared to barium studies and endoscopic findings, as far as parameters of disease activity are concerned. MATERIAL AND METHODS: Thirty five patients with pathologically proven CD were studied by means of helical single detector CT (13) or multidetector CT (22), after administration of low density contrast by mouth (13) or by nasojeunal tube (22). Eight hours later, all patients were studied with barium administered by mouth (13) or with barium and methilcellulose administered by nasojeunal tube (22). Clinical activity was assessed by CDAI score, ESR, CRP, alpha1 glycoprotein and fibrinogen levels. In twenty one patients, colonoscopy was also performed. RESULTS: Sensitivity of small bowel CT versus endoscopy was of 88% while sensitivity of barium studies was of 77% versus endoscopic findings, and it reached 100% for the combination of both exams. We found positive correlations between the detection at CT of "target sign" and a CDAI score > 150 or abnormal values of CRP, ESR, alpha1 glycoprotein. Abnormal ESR or fibrinogen levels were correlated with the detection of fistulas at CT scans. The diameter of enlarged mesenteric lymph nodes was correlated with alpha1 glycoprotein values. No similar correlations were detected for contrast radiology findings. DISCUSSION: This study underscores the clinical usefulness of performing small bowel CT in adjunct to conventional diagnostic studies in Crohn's disease patients. CT findings (either by oral route or nasojeunal tube) correlate with parameters of disease activity.

Magnetic resonance pancreatography (MRP): morphology and function.

MRCP is able to non-invasively assess the pancreatic ducts, with moderate/high agreement with ERCP: There is however a high number of false negative results, mainly due to the small size of the main pancreatic duct, especially in the tail, and side branches. Secretin stimulates the exocrine pancreas with accumulation of fluid and bicarbonates in the ductal system, and subsequent enlargement. This increase in caliber improves the assessment of the morphology of pancreatic ducts and their abnormalities. MRCP accuracy in assessing ductal abnormalities, improves after secretin administration. Furthermore, dynamic MRCP during secretin administration is also able to afford the functional evaluation of the pancreatic flow dynamics. Papillary stenosis, either idiopathic or due to Santorinicele, is easily diagnosed by means of S-MRCP. Furthermore a noninvasive assessment of the pancreatic exocrine reserve can be performed with dynamic MRCP during secretin administration.

Imaging of acute pancreatitis.

Pancreatitis is one of the most complex and clinically challenging of all abdominal disorders. It is classified according to clinical, morphologic and histologic criteria. The primary role of radiologic imaging in patients with suspected pancreatitis is to confirm or exclude the clinical diagnosis of pancreatitis. Second, if possible, the cause of the disease is established with the assessment of disease severity and detection of complications. Imaging can also provide guidance for percutaneous therapy. Sonography in acute pancreatitis is a good screening test in patients with suspected biliary pancreatitis and a mild clinical course. Contrast-enhanced CT is preferred for patients with acute pancreatitis because it can accurately diagnose and stage the disease and the necessary information for percutaneous management is provided. The diagnosis of acute pancreatitis on MRI relies on the presence of morphologic and peripancreatic changes. Pancreatic necrosis and complications of acute pancreatitis such as hemorrhage, pseudocysts or abscesses are well-examined by MRI.

Imaging of chronic pancreatitis.

Chronic pancreatitis is characterized by progressive, irreversible morphologic changes whose most common cause is excessive alcohol intake. Radiologic imaging plays a major role in the diagnosis, staging of disease severity, detection of complications and selection of treatment options. The sensitivity of US ranges from 60% to 70% while its specificity is higher reaching 80%-90% in the detection of abnormalities of main pancreatic duct. As for CT, its sensitivity and specificity in the diagnosis of chronic pancreatitis, in recent studies is 74% and 85% respectively. The performance of Magnetic Resonance cholangiopancreatography was shown to be enhanced by secretin stimulation with better visualization of ductal and parenchymal changes. However, endoscopic retrograde cholangiopancreatography is the most sensitive indicator of the presence and extent of the disease. Ductal abnormalities can be used to classify chronic pancreatitis.

High resolution spiral computed tomography of the pancreas.

Computed tomography (CT) is a very useful tool in the assessment of pancreatic disease. Searching for subtle signs, as in chronic pancreatitis or staging of adenocarcinoma, high spatial and contrast resolution is needed. The high resolution computed tomography (HRCT) technique for pancreatic scans, and its evolution from dynamic CT to multislice spiral CT, is described. 2D and 3D dimensional reconstructions are depicted and their role in diagnosis is focused. Together with spatial resolution, contrast enhancement protocols are discussed, aimed to achieve optimal contrast between the lesion and normal parenchyma.

Staging of pancreatic ductal adenocarcinoma with spiral CT and MRI.

Detection of pancreatic adenocarcinoma is crucial for accurate staging both with spiral CT and dynamic MRI; consequently an accurate technique is required and so-called pancreatic phase is recognized as the best one for tumor conspicuity. For vascular involvement optimal results have been achieved in assessing unresectability; vein involvement seems more difficult to be defined as it is sustained by a different spread compared to arterial involvement. Grading of vessel circumference contact represents the best tool in "venous" staging, but shape deformation and collateral veins dilation are also important signs. Lymph node staging is less accurate, lacking in specificity, but spiral CT demonstrated better results if compared with dynamic MRI. Assessment of liver metastases has been improved by the advent of spiral CT and dynamic contrast enhanced MRI, while peritoneal staging seems to be unaffected. In conclusion, both spiral CT and dynamic contrast enhanced MRI are accurate in pancreatic adenocarcinoma staging, mainly for vessels and liver involvement; no definite differences have been established, because only a few studies have compared them both with state-of-art techniques. Therefore standardized multicentric trials are desirable. Up to now, the choice of which technique to employ should be based on local expertise; moreover, the aggressive approach of surgical equipes should be kept in mind.

Role of diagnostic imaging in abdominal lymphadenopathy.

Abdominal lymph node chains and route of lymph drainage of various organs (stomach, duodenum, liver, gallbladder, pancreas, small intestine, appendix, blind intestine, colon rectum) are analyzed according to their location. The role of conventional radiology and diagnostic imaging is evaluated in the study of abdominal lymphatic system with particular reference to lymphangiography and the new procedures of sonography, CT and MRI. Present methods used in inflammatory abdominal lymphadenopathy with special attention to tuberculous lymphadenitis, liver cirrhosis, neoplastic abdominal lymphadenopathy, colorectal and pancreatic cancer, are illustrated. Combined modality imaging is considered in gastric cancer based on the evolution of the classification of gastric lymph nodes. The role of sonography, endoscopic ultrasonography, spiral CT and MRI is assessed in gastric cancer N staging. A retrospective study is analyzed and perspectives for the application of a new CT protocol are proposed. PET potentialities in the study of abdominal lymph nodes are examined.

CT enterography with polyethylene glycol solution vs CT enteroclysis in small bowel disease.

OBJECTIVE: The aim of the study is to compare CT enterography with polyethylene glycol solution (PEG-CT) with CT enteroclysis (CT-E) in patients with suspected small bowel disease. METHODS: 145 patients underwent abdominal contrast-enhanced 16-row multidetector CT after administration of 2000 ml of PEG by mouth (n = 75) or after administration of 2000 ml of methylcellulose by nasojejunal tube (n = 70). Small bowel distension, luminal and extraluminal findings were evaluated and compared with small bowel follow-through examination in 60 patients, double contrast enema in 50, surgery in 25 and endoscopy in 35. Statistical evaluation was carried out by χ² testing. For both techniques we have also calculated the effective dose and the equivalent dose in a standard patient. RESULTS: Crohn's disease was diagnosed in 64 patients, neoplasms in 16, adhesions in 6. Distension of the jejunum was better with CT-E than PEG-CT (p<0.05: statistically significant difference). No significant difference was present for others sites (p>0.05). Evaluation of pathological ileal loops was good with both techniques. The values of sensitivity, specificity and diagnostic accuracy were respectively 94%, 100% and 96% with CT-E, and 93%, 94% and 93% with PEG-CT. The effective dose for PEG-CT was less than the dose for the CT-E (34.7 mSv vs 39.91 mSv). CONCLUSION: PEG-CT shows findings of Crohn's disease as well as CT-E does, although CT-E gives better bowel distension, especially in the jejunum, and has higher specificity than PEG-CT.