Sex: male
Age: 60 years
History
The patient complained about mucous and haemorrhagic stools since Oktober 1996, previous to this episode the patient was healthy.
Laboratory data
Tumour-marker CA 19-9 was elevated to 45.80 kU/L (References: 0.0 - 37.0).
Physical findings
Unremarkable
Case text
The patient was first seen because of rectal bleeding. The radiological diagnostic work-up including a endorectal ultrasound and magnetic resonance imaging
Image 1-2
Endorectal ultrasound.
Mechanical rotating endoprobe, 7MHz, a latex ballon filled with 60 ml degased water is attached over the probe. The endoprobe is inserted in the middle third of the rectum, 10 cm from the anal verge (image 1) and 2 cm higher (image 2).
Image 3-7
Double contrast MRI of the pelvis.
Axial T1-weighted (TR/TE 535/12 ms, 4mm slicethickness, image 3). Sagittal T1-weighted image (8mm slice thickness, image 4). Sagittal T2-weighted image (TR/TE 3000/120, 8mm; image 5); post contrast rectal. Axial and sagittal T1-weighted images post contrast i.v. (images 6,7).
Image 1-2
1. What is the abnormality present on the rectal ultrasound?
Circular hypoechoic lesion, the normal sonographic anatomy of the rectal wall is disrupted
2. Is the tumour penetrating throug the rectal wall?
No, the tumour is confined to the rectal wall, the outer interface is not interrupted
3. Are there enlarged lymphnodes?
No enlarged lymph nodes are seen.
Image 3-7
4. What are the abnormalities present on the MRI of the pelvis?
Circular stenotic lesion in the middle and upper third of the rectum; the lesion is hyperintense on theT2-weighted image and shows an enhancement after i.v. application of Gadodiamid.
5. Does MRI provide any additional information?
Yes, infiltration of the perirectal fat on the right side, best seen on the axial orientation after Gadodiamid; precise demonstration of the location, upper and lower margins of the cancer.
6. What is your diagnosis?
Rectal cancer with infiltration of the perirectal fat, no lymphnode metastasis
Final diagnosis
Adenocarcinoma of the rectum (pT3/ N0).
Differential diagnosis
None.
Discussion
To date, transrectal ultrasound is the method of chioce for preoperative staging of rectal carcinoma. This method shows high sensitivty rates ranging from 67 to 96% for tumour extension though the bowel wall (1). The wide range of sensitivities in different studies reflects the operator dependence, which is a clear disadvantage of this method. Moreover, transrectal ultrasound cannot be used for staging of tumors in the upper parts of the rectum and rectum/sigmoid junction. The method cannot be applied in patients were the tumor causes a stenosis.
Studies in staging rectal carcinoma with MR imaging using a conventional body coil has been limited in the deliniation of the tumor. With the help of transrectal coil it has been possible to visualize the layers of the rectal wall, a prerequisite for accurate staging. Despite these good results, MR using a transrectal coil very much suffers from similar limitations as transrectal ultrasound.
Using a double contrast technique it has been shown more recently by Wallengren et al. to obtain a high sensitivity and accuracy in the MRI staging of rectal tumors (2). Shortly after the introduction of DCMRI by Wallengren in Lund, a multicenter trial was set up in Europe. The trial was designed for the imaging of rectal cancer only and it had three objectives: firstly, the most important information to be gained was the finding of the appropriate dosis of Ferristene (Abdoscan® -Nycomed Amersham) for an optimal image quality. Secondly, the accuracy of stage-prediction was to be evaluated in comparison with the pathologist's report of the specimen. Finally, the method had to be compared with endorectal ultrasound.
First experiences indicate, that double-contrast MRI provides a precise demonstration of upper and lower margins of rectal cancer and of the familiar structures of the adjacent organs. In this study the mucosa, the muscularis propria and surrounding fat of the rectal wall were clearly visable after Ferristene was applied rectally in addition to an intravenous application of Gadodiamide injection. Analysis of the whole trial population (112 patients) has shown an overall sensitivity of 100% as the ability to identify tumour-stages lager T2. The specificity as the ability to detect T1 and T2 was 67% and the overall accuracy was about 90%. Lymphnode staging was inaccurate with either method in about a third of the cases, when compared with the pathologist's report.
Transrectal ultrasound is still more reliable than DCMRI for anticipating the T-stage, with the restriction that endosonography may not always be possilble due to tumour-stenosis. But apparently DCMRI provides a much more subtle imaging of the invasion of adjacent organ-structures, and at present DCMRI appears to be or to become at least a valuable tool for preoperative T- and N-staging.