Spiral CT colonography in inflammatory bowel disease

Virtual Colonoscopy in Colorectal Cancer Screening

Colorectal cancer is the third most commonly diagnosed tumor in both males and females in the United States. Current modalities for colorectal cancer screening include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Virtual colonoscopy is a promising new method for assessing the entire colon. Vining and Gelfand first described this technique in 1994. Since then, virtual colonoscopy has been shown to be extremely safe and well tolerated by patients. Indications for virtual colonoscopy include screening for polyps, incomplete or failed colonoscopy, and preoperative assessment of the colon proximal to an occlusive cancer or even redundant fixed or stenotic colon that cannot be endoscopically traversed. Virtual colonoscopy may dramatically increase patient participation in screening programs, leading to early diagnosis of colorectal cancer. Although virtual colonoscopy seems a potentially attractive screening method for colorectal cancer, the cost-effectiveness of this method is yet to be determined.

Differential Diagnosis of Colonic Strictures: Pictorial Review with Illustrations from Computed Tomography Colonography

Strictures of the colon can lead to significant morbidity requiring surgical management. The etiology of strictures is broad and generally categorized as benign, malignant, or pseudostrictures. Computed tomography (CT) is a crucial imaging modality in the assessment and characterization of colonic pathologies but colonoscopy remains the diagnostic gold standard. However, in the setting of incomplete colonoscopy due to strictures, the imaging features of CT will be relied on. This review will focus on the CT features of different colon pathologies leading to strictures and will be illustrated with images from 10 years of experience with CT colonography at our institutions from 2002-2012 (Hotel Dieu Hospital, Queen's University and Mount Sinai Hospital, University of Toronto).

Water enema multidetector CT technique and imaging of diverticulitis and chronic inflammatory bowel diseases

BACKGROUND

Water enema multidetector computed tomography (WE-MDCT) is currently considered the most accurate imaging modality to provide high-resolution multiplanar visualisation of the colonic wall and surrounding structures.

METHODS

This pictorial review presents our experience with WE-MDCT applications outside colorectal tumour staging, particularly for investigating diverticular disease and chronic inflammatory bowel diseases. A detailed explanation of the technique is provided, including patient preparation, the acquisition protocol, and study interpretation.

RESULTS

WE-MDCT allows accurate preoperative visualisation of diverticular disease, acute and complicated diverticulitis. Ulcerative, indeterminate, or Crohn's colitis can be assessed including longitudinal distribution, mural thickening and enhancement patterns, pseudopolyps, associated perivisceral changes, adjacent organ involvement, and features suggesting carcinoma. Elective WE-MDCT represents a useful complementary technique in patients with impossible, incomplete, or inconclusive endoscopy, can allow study of a stricture's features and the upstream bowel, and helps planning medical, endoscopic, or surgical treatments.

CONCLUSION

Urgent WE-MDCT with limited or no bowel preparation may prove useful in acutely symptomatic patients, as it may obviate a risky or contraindicated endoscopy, can determine disease severity, and allows making correct therapeutic choices.

TEACHING POINTS

• Water enema multidetector CT provides high-resolution multiplanar visualisation of the colonic wall. • WE-MDCT allows accurate visualisation of diverticular disease, acute and complicated diverticulitis. • In chronic inflammatory bowel diseases WE-MDCT depicts the distribution, mural and perivisceral changes. • Elective WE-MDCT usefully complements incomplete endoscopy to assess strictures and upstream colon. • Urgent WE-MDCT with limited or no bowel preparation in acute diseases may obviate endoscopy.

Initial experience with computed tomographic colonography applied for noncolorectal cancerous conditions

PURPOSE

The aim of this study was to asses retrospectively the performance of computed tomography colonography (CTC) for noncolorectal cancerous conditions.

MATERIAL AND METHODS

A total of 44 patients with non-colorectal cancerous conditions underwent CTC. We researched the indications for CTC or present illness and evaluated the CTC imaging findings. We assessed whether diagnosis by CTC reduced conventional colonoscopic examinations.

RESULTS

A total of 47 examinations were performed in 44 patients. The indications for CTC or a present illness were as follows: 15 patients with impossible or incomplete colonoscopy, 7 with diverticular disease, 6 with malignancy (noncolorectal cancer), 6 with Crohn's disease, 4 suspected to have a submucosal tumor on colonoscopy, 2 with ischemic colitis, and 4 with various other diseases. Colonic findings were diagnosed on CTC in 36 examinations, and extracolonic findings were identified in 35 of 44 patients. In all, 17 patients had undergone colonoscopy previously, 9 (52.9%) of whom did not require further colonoscopy by CTC. Five patients underwent colonoscopy after CTC.

CONCLUSION

The indications for CTC were varied for patients with noncolorectal cancerous conditions. CTC examinations could be performed safely. Unlike colonoscopy or CT without preparation, CTC revealed colonic and extracolonic findings and may reduce the indication of colonoscopy in patients with noncolorectal cancerous conditions.

Role of CT colonography in inflammatory bowel disease

CT colonography (CTC), or virtual colonoscopy, is a non-invasive imaging method that uses CT data sets combined with specialized imaging software to examine the colon. CTC is not used routinely in patients with inflammatory bowel disease (IBD). However, investigating contemporarily the colon, other abdominal organs and the peritoneum with CTC is at times useful in patients with IBD, especially when other diagnostic tools fail. Furthermore, since symptoms of colorectal cancer sometimes superimpose to those of inflammatory disease, it may happen to image patients with IBD incidentally. If clinical signs are suggestive for inflammatory disease, exam technique should be modified accordingly and distinguishing radiological findings searched for.

[Experience with CT colonography (virtual colonoscopy) from the view of gastroenterologists]

Colonoscopy is a golden standard in the diagnostics of intraluminal diseases of the large intestine. Its advantage is the possibility of histological sampling (biopsy) and therapeutical interventions. In case of technical difficulties (stenosis, severe inflammation, diverticulosis, anatomical alterations) or lack of informed consent of the patient double contrast colonography is the routine diagnostic tool for the examination of the entire large intestine. The spread of the use of colon capsule as a novelty is keeping us waiting. A very important criteria is the adjudication of the expansion of the intestinal disease to the surrounding and distant organs. The correct diagnostics are the base of therapy planning. CT colonography as a standardizable imaging method can give information at once about the intraluminal aberrations, the spread to the surroundings and the abdominal status. The rapid, minimal invasive technology without sedation using multidetector CTs makes the method widely applicable.

AIMS

The authors search for the locus of CT colonography in the diagnostics of non-malignant diseases of the large intestine, in the screening of colorectal carcinoma and during tumor staging.

METHOD

Data of 92 males (mean age: 61.2+/-12.3 years) and 146 females (mean age 61.4+/-12.5 years) were collected after CT colonography had been performed at Zala County Hospital between September 2002 and January 2007. Indications, protocols and results determining further business have been reviewed.

RESULTS

The reason of CT colonography was the failure of colonoscopy in 29% of the 238 patients. In 45/238 patients (19%) stricture of the colon, in 23/238 cases (10%) pain, lack of compliance and technical difficulties were the reasons of failure. In 60% of the remaining 23 persons organic intestinal diseases were diagnosed. In 151 cases (63%) the lack of informed consent for colonoscopy was the reason of radiological examinations, pathological aberrations were found in every second patient. Aiming to learn the method, CT colonography was performed after total colonoscopy in 19/238 patients after informed consent.

CONCLUSIONS

CT colonography is a useful tool in the algorithm of diagnostics of colorectal diseases in the case of lack of performing total colonoscopy.

Antiglycan antibodies as serological markers in the differential diagnosis of inflammatory bowel disease

BACKGROUND

The objective of the study was to evaluate the diagnostic accuracy of recently developed antiglycan serological tests in clinical practice for the diagnosis of Crohn's disease.

METHODS

This study was a cohort analysis of both clinical and biochemical parameters of patients with diagnosed inflammatory bowel disease compared with those in a control population. Antiglycan antibodies were determined using commercially available enzyme immunoassays. The setting was the outpatient unit of the gastroenterology department of a large, tertiary-care referral academic hospital. Participants were 214 consecutive patients, enrolled over a 5-month period, including 116 with Crohn's disease and 53 with ulcerative colitis, as well as 45 with other gastrointestinal diseases and 51 healthy controls.

RESULTS

Anti-Saccharomyces cerevisiae antibodies showed the best performance (54% sensitivity and 88%-95% specificity for Crohn's disease). Among patients with negative anti-Saccharomyces antibodies, 19 (34%) had high titers of at least another tested antiglycan antibody. Anti-Saccharomyces and anti-laminaribioside antibodies were associated with disease involving the small bowel and with penetrating or stricturing phenotype. Anti-laminaribioside was significantly higher in patients with a familial history of inflammatory bowel disease.

CONCLUSIONS

The new proposed serological markers are significantly associated with Crohn's disease, with low sensitivity but good specificity. About one third of anti-Saccharomyces-negative patients may be positive for at least 1 of those markers. Antiglycan antibodies appear to be associated with characteristic localization and phenotype of the disease.

CT colonoscopy in inflammatory bowel disease

Virtual colonoscopy is used worldwide for the detection of colon polyps, but this technique has not been used much for the evaluation of inflammatory bowel diseases. The advent of multidetector-computed tomography and the use of high quality 3D and virtual images opened up the opportunity to assess these patients with this non-invasive technique. Early and late colonic changes are illustrated.

Pitfalls in Multi–Detector Row CT Colonography: A Systematic Approach

Thin-section multi-detector row computed tomographic (CT) colonography is a powerful tool for the detection and classification of colonic lesions. However, each step in the process of a CT colonographic examination carries the potential for misdiagnosis. Suboptimal patient preparation, CT scanning protocol deficiencies, and perception and interpretation errors can lead to false-positive and false-negative findings, adversely affecting the diagnostic performance of CT colonography. These problems and pitfalls can be overcome with a variety of useful techniques and observations. A relatively clean, dry, and well-distended colon can be achieved with careful patient preparation, thereby avoiding the problem of residual stool and fluid. Knowledge of the morphologic and attenuation characteristics of common colonic lesions and artifacts can help identify bulbous haustral folds, impacted diverticula, an inverted appendiceal stump, or mobile polyps, any of which may pose problems for the radiologist. A combined two-dimensional and three-dimensional imaging approach is recommended for each colonic finding. A thorough knowledge of the various pitfalls and pseudolesions that may be encountered at CT colonography, along with use of dedicated problem-solving techniques, will help the radiologist differentiate between definite colonic lesions and pseudolesions.

Virtual colonoscopy-induced perforation in a patient with Crohn's disease

We report a case of sigmoid colon perforation in a patient with Crohn's disease undergoing computed-tomographic (CT) colonography. A 70-year-old patient with Crohn's disease with terminal ileitis and sigmoid stricture underwent CT colonography after incomplete conventional colonoscopy. During the procedure, the colon was inflated by air insufflation and the patient developed abdominal pain with radiological evidence of retroperitoneal and intraperitoneal free gas. Hartmann's operation was performed. This case highlights that CT colonography is not risk-free. The risk of perforation may be higher in patients with inflammatory bowel disease.

Virtual colonoscopy-induced perforation in a patient with Crohn’s disease

We report a case of sigmoid colon perforation in a patient with Crohn’s disease undergoing computed-tomographic (CT) colonography. A 70-year-old patient with Crohn’s disease with terminal ileitis and sigmoid stricture underwent CT colonography after incomplete conventional colonoscopy. During the procedure, the colon was inflated by air insufflation and the patient developed abdominal pain with radiological evidence of retroperitoneal and intraperitoneal free gas. Hartmann’s operation was performed. This case highlights that CT colonography is not risk-free. The risk of perforation may be higher in patients with inflammatory bowel disease.

CT colonography: techniques, indications, findings

Computed tomographic colonography (CTC) is a minimally invasive technique for imaging the entire colon. Based on a helical thin-section CT of the cleansed and air-distended colon, two-dimensional and three-dimensional projections are used for image interpretation. Several clinical improvements in patient preparation, technical advances in CT, and new developments in evaluation software have allowed CTC to develop into a powerful diagnostic tool. It is already well established as a reliable diagnostic tool in symptomatic patients. Many experts currently consider CTC a comparable alternative to conventional colonoscopy, although there is still debate about its sensitivity for the detection of colonic polyps in a screening population. This article summarizes the main indications, the current techniques in patient preparation, data acquisition and data analysis as well as imaging features for common benign and malignant colorectal lesions.

Inflammatory chronic disease of the colon: how to image

Inflammatory bowel disease, including Crohn's disease and UC, is a chronic disorder of the gastrointestinal tract. The inflammatory process in UC is confined to the mucosa and submucosa and it involves only the colon. In contrast, in Crohn's disease the inflammation process extends through the bowel wall layers and it can involve any part of gastrointestinal tract. Moreover, inflammatory bowel disease of the colon may be associated with complications, such as toxic megacolon, fulminant colitis, acute bleeding, fistulas and abscesses. Radiographic imaging studies are useful for the diagnosis of inflammatory bowel disease, and may be used to assess the extent and severity of disease, rule out complications, and monitor the response to therapy. The double-contrast barium study is a valuable technique for diagnosing inflammatory bowel disease colonic alterations, even in patients with early mucosal abnormalities. The earliest finding of UC is characterized by a fine granular appeareance of the colonic mucosa, usually involving the rectosigmoid junction. In chronic UC double-contrast enema may reveal marked colonic shortening with tubular narrowing of the bowel and loss of haustration. The earliest radiographics findings of Crohn's disease are represented by aphthous ulcers. As disease progresses, aphthous ulcers may enlarge and coalesce to form stellate or linear areas of ulceration. In advanced Crohn's disease, transmural ulceration may lead to the development of fissures, sinus tracts, fistulas, and abscesses. Cross sectional studies such as computed tomography, magnetic resonance imaging and sometimes ultrasound, are useful alternative tools not only in the assessment of bowel wall abnormalities, but also for the assessment of extraluminal alterations in patients with advanced disease.

Evaluation of contrast-enhanced computed tomographic colonography in detection of local recurrent colorectal cancer

AIM: To evaluate the diagnostic accuracy, sensitivity, specificity of contrast-enhanced computed tomographic colonography in detecting local recurrence of colorectal cancer.

METHODS: From January 2000 to December 2004, 434 patients after potentially curative resection for invasive colorectal cancer were followed up for a period ranging from 20 to 55 mo. Eighty of the four hundred and thirty-four patients showing strong clinical evidence for recurring colorectal cancer during the last follow-up were enrolled in this study. Each patient underwent contrast-enhanced computed tomographic colonography and colonoscopy on the same day. Any lesions, biopsies, identified during the colonoscopic examination, immediate complications and the duration of the procedure were recorded. The results of contrast-enhanced computed tomographic colonography were evaluated by comparing to those of colonoscopy, surgical finding, and clinical follow-up.

RESULTS: Contrast-enhanced computed tomographic colonography had a sensitivity of 100%, a specificity of 83% and an overall accuracy of 94% in detecting local recurrent colorectal cancer.

CONCLUSION: Conventional colonoscopy and contrast-enhanced tomographic colonography can complement each other in detecting local recurrence of colorectal cancer.

Multi-detector CT-colonography in inflammatory bowel disease: prospective analysis of CT-findings to high-resolution video colonoscopy

AIM

Prospective analysis of multi-detector CT-colonography (MDCTC) in patients with inflammatory bowel disease (IBD) compared to high-resolution video-endoscopy (HRVC).

MATERIALS AND METHODS

Twenty-one patients (mean age 49.6 years) with Crohn's disease or ulcerative colitis underwent MDCTC (Somatom Volume Zoom, Siemens, Erlangen; 1mm collimation, Pitch 8, 100 mAs, 120 kVp). HRVC was performed within 2 h after MDCTC. MDCTC was analyzed by two blinded readers. MDCTC-findings including bowel wall alterations and extraintestinal changes were compared to results of HRVC.

RESULTS

Over-all-sensitivity was 100% for endoluminal lesions with correct diagnosis of two cancers. Acute and chronic IBD were correctly identified by MDCTC in 63.6%, and 100%, respectively, with a specificity of 75%, and 100%. Sensitivity, specificity, positive and negative predictive values of MDCTC for diagnosis of acute and chronic disease were best for chronic disease. Sensitivity was worst for acute ulcerative colitis and specificity was worst for acute Crohn's disease. Haustral loss was seen only in ulcerative colitis. Pseudopolyps and fistulae were findings exclusive to Crohn's disease. Particularly extraintestinal findings as increased vascularization and local lymphadenopathy correlated well with endoscopic definition of acute disease. Because of the possibly more vulnerable colonic wall in acute inflammatory bowel disease, the air inflation for MDCTC should be performed most carefully to avoid any risk of colonic perforation.

CONCLUSION

MDCTC may help to distinguish between patients with acute and chronic IBD. Especially extraintestinal complications, tumorous as well as pseudo-tumorous lesions can be detected with high sensitivity and specificity.

Evolving diagnostic modalities in inflammatory bowel disease

Over the past several years, significant advances have been made in the diagnostic techniques used in the management of ulcerative colitis and Crohn's disease. These advances have occurred mainly in the area of gastrointestinal endoscopy and radiology. Capsule endoscopy and double-balloon endoscopy have permitted better visualization of the small bowel mucosa. Advanced imaging techniques, including chromoendoscopy, magnification endoscopy, confocal endomicroscopy, and spectroscopy, may aid in the diagnosis of colorectal neoplasia in patients with long-standing disease. Improved radiographic imaging techniques based on computed tomography and magnetic resonance imaging allow noninvasive means of evaluating the small bowel in patients with known or suspected Crohn's disease. Finally, positron emission tomography is an investigative tool for inflammatory bowel disease that may also aid in the detection of inflammation in these diseases.

Small bowel hydro-MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?

PURPOSE

To assess the impact of an additional rectal enema filling in small bowel hydro-MRI in patients with Crohn's disease.

MATERIALS AND METHODS

A total of 40 patients with known Crohn's disease were analyzed retrospectively: 20 patients only ingested an oral contrast agent (group A), the other 20 subjects obtained an additional rectal water enema (group B). For small bowel distension, a solution containing 0.2% locust bean gum (LBG) and 2.5% mannitol was used. In all patients, a breathhold contrast-enhanced T1w three-dimensional volumetric interpolated breathhold examination (VIBE) sequence was acquired. Comparative analysis was based on image quality and bowel distension as well as signal-to-noise ratio (SNR) measurements. MR findings were compared with those of conventional colonoscopy, as available (N = 25).

RESULTS

The terminal ileum and rectum showed a significantly higher distension following the rectal administration of water. Furthermore, fewer artifacts were seen within group B. This resulted in a higher reader confidence for the diagnosis of bowel disease, not only in the colon, but also in the ileocecal region. Diagnostic accuracy in diagnosing inflammation of the terminal ileum was 100% in group B; in the nonenema group there were three false-negative diagnoses of terminal ileitis.

CONCLUSION

Our data show that the additional administration of a rectal enema is useful in small bowel MRI for the visualization of the terminal ileum. The additional time needed for the enema administration was minimal, and small and large bowel pathologies could be diagnosed with high accuracy. Thus, we suggest that a rectal enema in small bowel MR imaging be considered.

Ex vivo histology-correlated optical coherence tomography in the detection of transmural inflammation in Crohn's disease

BACKGROUND AND AIMS

Distinguishing Crohn's disease (CD) from ulcerative colitis (UC) can be difficult. Transmural inflammation, a key feature of CD, cannot be assessed by conventional colonoscopy with biopsy. Optical coherence tomography (OCT) provides high-resolution, cross-sectional images of the gut wall and might become a new diagnostic tool. The aims of this study were to perform histology-correlated OCT on surgical specimens of CD and UC and to determine its diagnostic accuracy.

METHODS

Colectomy specimens from patients with a preoperative diagnosis of CD (N = 24) or UC (N = 24) were studied with OCT in the operating room. OCT and histopathology were assessed blindly, and diagnostic accuracy of OCT was assessed.

RESULTS

Eight preoperatively identified UC patients (33%) with transmural inflammation on postoperative histology were diagnosed with CD, and all 8 had a disrupted layered structure on OCT, a characteristic feature of transmural disease. Sixteen UC patients (67%) had superficial inflammation on histology; of them, 13 (81%) had an intact layered structure on OCT. All 24 preoperative CD patients had transmural inflammation on histology, and 23 (96%) had a disrupted layered structure on OCT. Of 585 histology-OCT image sets from the 48 patients, 152 sets (26%) had transmural inflammation on histology. The sensitivity and specificity for OCT to detect transmural disease were 86% and 91%, respectively.

CONCLUSIONS

Transmural inflammation, as characterized by disruption of the layered structure of colon wall on OCT, is an accurate marker for the diagnosis of CD. Ex vivo OCT predicted transmural inflammation on postoperative histopathology.

Imaging of inflammatory bowel disease: CT and MR

Cross-sectional imaging has come to play a central role in the imaging of the abdomen. Concurrent to this, the role of CT and MRI in the imaging of inflammatory bowel disease has also increased in importance. These modalities offer numerous advantages over more traditional methods of radiologic diagnosis, and provide essential information not only for initial diagnosis, but for management, follow-up and detection of potential complications. On the horizon are several derivative techniques involving CT and MRI, potentially in combination with PET imaging; these may further improve the specificity and sensitivity of imaging modalities for diagnosis of inflammatory bowel disease.

Virtual colonoscopy compared with conventional colonoscopy for stricturing postoperative recurrence in Crohn's disease

BACKGROUND

The place of virtual colonoscopy (VC) in patients with Crohn's disease (CD) requiring endoscopic follow-up after surgery is unknown. The authors compared findings from VC versus conventional colonoscopy (CC) for assessing the postoperative recurrence of CD.

METHODS

Sixteen patients with ileocolonic anastomosis for CD were prospectively enrolled from January 2001 to January 2002. Recurrence was assessed by CC according to Rutgeerts et al. VC was performed with a computed tomography scanner, with images examined by three radiologists who were unaware of the endoscopic findings.

RESULTS

CC showed perianastomotic recurrence in 15 of 16 patients. Perianastomotic narrowing or stenosis was detected by VC in 11 of these 15 patients. There were 11 true positive, 1 true negative, 0 false-positive, and 4 false-negative findings (73% sensitivity, 100% specificity, 100% positive predictive value, 20% negative predictive value, 75% accuracy). Among the eight patients showing a rigid stenosis of the anastomosis not allowing passage of the colonoscope, VC detected narrowing or stenosis in seven patients.

CONCLUSIONS

The current findings suggest that although the widespread use of VC in CD is currently not indicated because of possible false-negative findings, this technique may represent an alternative to CC in noncompliant postsurgical patients with a rigid stenosis not allowing passage of the endoscope.

Comparison of multidetector CT and barium studies of the small bowel: inflammatory bowel disease in children

OBJECTIVE

We compared barium studies of the small bowel with multidetector CT (MDCT) in the evaluation of the small bowel during the initial presentation of inflammatory bowel disease in a pediatric population.

SUBJECTS AND METHODS

This was a prospective study. Eighteen children undergoing workup for inflammatory bowel disease underwent MDCT, colonoscopy, and barium studies of the small bowel before commencement of therapy. Examinations were independently reviewed. The patients and their guardians completed a questionnaire assessing the acceptability of each study.

RESULTS

In 13 of 18 children, the findings of MDCT and barium studies of the small bowel concurred in the evaluation of terminal ileum disease. In three of these children, MDCT detected skip segments of small-bowel disease not detected on barium studies of the small bowel. In two of 18 children, the terminal ileum was not visualized on barium studies of the small bowel, whereas MDCT showed substantial terminal ileum disease in both children. In three of 18 children, there was discordance between the two tests regarding terminal ileum disease. However, these discordant imaging findings were all subtle. In addition, MDCT revealed extraenteric abnormalities, clinically relevant in two children (ureteric obstruction and perirectal abscess), and showed the colon in all children, seven of whom had incomplete colonoscopy. The questionnaire revealed that 16 of 18 patients preferred MDCT to small-bowel barium studies. The reasons given were poor tolerance of oral barium and the long duration of barium studies of the small bowel.

CONCLUSION

MDCT can be an alternative to barium studies of the small bowel for evaluation of the small bowel in patients with inflammatory bowel disease. MDCT also offers additional, clinically relevant information not obtained by small-bowel barium studies.

Unusual causes of colonic wall thickening on computed tomography

Computed tomography (CT) appearances in "colitis" are often non-specific, and include mural thickening and mesenteric fat stranding. In the western world, the majority of cases will have, or be subsequently diagnosed with, inflammatory bowel disease, pseudomembranous colitis or ischaemic colitis. However, other rare conditions may also produce these rather non-specific signs. We present a number of cases demonstrating colonic wall thickening on CT due to rarer diagnoses, which are correlated with the histopathological features. Some of these CT appearances have not been described previously in the literature.