mri in staging

7/27/2019 MRI in staging

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ROLE OF MRI IN STAGINGRECTAL CARCINOMA


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MAGNETIC RESONANCE IMAGING Magnetic resonance imaging (MRI), nuclear magnetic resonance

imaging (NMRI), or magnetic resonance tomography (MRT) is a

medical imaging technique used in radiology to visualize internal

structures of the body in detail.

It does not use radiation (x-rays). Single MRI images are called slices. The images can be stored on a

computer or printed on film. One exam produces dozens or

sometimes hundreds of images.


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Abdominal MRI

Chest MRI

Cranial MRI

Heart MRI

Spine MRI


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PREPARATION

If we have claustrophobia, we may be given a medicine to help us

feel sleepy and less anxious, or doctor may suggest an "open"

MRI.

Before the test,

Artificial heart valves Heart defibrillator or pacemaker

Inner ear (cochlear) implants

Kidney disease or dialysis or allergic

Recently placed artificial joints Vascular stents


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PROCEDURE

We may be asked to wear a hospital gown without zippers or snaps

Lie on a narrow table, which slides into a large tunnel-shaped

scanner.

Some exams require a special dye (contrast). The dye helps the

radiologist see certain areas more clearly. Coils may be placed around the head, arm, or leg, or other areas to

be studied. These help send and receive the radio waves, and help

the quality of the images.

The test lasts about 30-60 minutes, but may take longer.


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ROLE OF MRI IN STAGING RECTAL CANCER

Rectal cancer is a common malignancy that continues to have a

highly variable outcome, with local pelvic recurrence after surgical

resection usually leading to incurable disease.

The success of tumor excision depends largely upon accurate

tumor staging and appropriate surgical technique. Magnetic resonance (MR) imaging is increasingly being used to

evaluate tumor resectability in patients with rectal cancer and to

determine which patients can be treated with surgery alone and

which will require radiation therapy to promote tumor regression.


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High-spatial-resolution MR imaging has proved useful in

clarifying the relationship between a tumor and the mesorectal

fascia, which represents the circumferential resection margin at total

mesorectal excision.

Phased-array surface coil MR imaging in particular plays a vitalrole in the therapeutic management of rectal cancer.

At present, phased-array MR imaging best fulfills the clinical

requirements for preoperative staging of rectal cancer.


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TWO AIMS OF MRI

Comparison between MRI2 and histopathology or between MRI2

and MRI1.

Treatment modification

- No surgery

-Local excision

-Standard TME

-Extended TME


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ANATOMICAL LANDMARKS OF RECTUM

The anal verge marks the lowermost portion of the anal canal and

begins where the skin stops and where the anal mucosa starts.

The dentate line is located about 1.5-2 cm upwards from the anal

verge.

The surgical anal canal extends about 3-4 cm, being shorter inwomen (2-3 cm), and ends at the anorectal ring or at the upper

portion of the puborectal muscle.

The surgical rectum extends for 12-15 cm endoscopically from the

anal verge.

Surrounding the rectum, there is a layer of fat, the perirectal or themesorectal fat. The perirectal fat is often referred to as

mesorectum.


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STAGING OF RECTAL TUMOUR

For optimal preoperative treatment planning of rectal cancer,

adequate local staging is of paramount importance.

Factors associated with prognosis are tumour height, T-stage,

extramural tumour growth, lymph node status, vascular and neural

invasion, threatened CRM and overgrowth to adjacent structures.


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TNM(TUMOUR-NODE-METASTASIS)

T represent the extend of local spread and there are four grades:

T1-tumour invasion through muscularis mucosae, but not into

muscularis propria;

T2-tumour invasion into but not through the muscularis propria;

T3-tumour invasion through the muscularis propria, but not through

the serosa or mesorectal fascia;

T4-tumour invasion through the serosa or mesorectal fascia.


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N describes the nodal involvement: N0-no lymph node involvement;

N1-1 to 3 involved lymph nodes;

N2-4 or more involved lymph nodes.

M indicates the presence of distant metastases:

M0-no distant metastases

M1-distant metastases


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TUMOUR HEIGHT AND SIZE


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INDICATIONS FOR MRI IN RECTAL CANCER

To evaluate the local extent of the tumour, before or perhaps also

during/after preoperative treatment.

Local recurrence can also be an indication for MRI.

Finally, sometimes MRI is used for a definitive diagnosis of rectal

cancer.


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DISADVANTAGES OF MRI

MRI scanners are very expensive.

Some people feel claustrophobic while they are having a MRI scan.

MRI scanners can be affected by movement, making them

unsuitable for investigating problems such as mouth tumours

because coughing or swallowing can make the images that areproduced less clear.


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REFERENCE

http://radiographics.rsna.org/content/26/3/701.f

ull

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC

3259411/ BROWSES INTRODUCTION TO THE

SYSTEMS AND SIGNS Of SURGICAL

DISEASE. BAILEY & LOVES
http://radiographics.rsna.org/content/26/3/701.fullhttp://radiographics.rsna.org/content/26/3/701.fullhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259411/http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259411/http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259411/http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259411/http://radiographics.rsna.org/content/26/3/701.fullhttp://radiographics.rsna.org/content/26/3/701.full

mri in staging

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