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DIAGNOSTIC RADIOLOGY TESTS INFORMATION

MRI with Contrast is the preferred scan for suspected cancers. Given the high resolution of MRI,and the ability to so clearly outline the blood vessels, an "MRA" (Magnetic ResonanceAngiography) obtained at the same time allows good determination of whether crucial blood

vessels are blocked or tortuous from aneurysm, narrowing, or tumor.

Historically angiography was done as a separate test to evaluate blood vessels by putting contrastdye into them, but it can now be done with the same technique as MRI with Contrast. MRI is ingeneral the better test to look at the brain, soft tissues in the body, and extent of tumor

penetration into organs than CT Scan. Since it does not use radiation, there is no concern aboutthe radiation exposure with repetitive testing. It is however more expensive than CT (about 3times as costly) and so is more judiciously ordered. MRI is seldom done on the whole body, butinstead in distinct regions as with CT Scan:

MRI of the Head - This frequently ordered test is usually gotten following a CT Scan which issuspicious, or if the CT of the brain does not show anything but the doctor is still suspecting alesion in the brain. Tumors starting within the brain, or cancer spreading to the brain from other organs, are easily seen using MRI with contrast. Since tumors tend to have a rich blood supply,they commonly enhance brightly when contrast is given. Also, areas of swelling around thetumor, called "peritumoral edema" will enhance. For malignant tumors, there are often cancer cells found in this surrounding edema fluid. MRI helps the physicians determine the feasibility of surgically removing the tumor - that is its "resectability". Although a tumor can be verysuspicious as being cancerous by MRI, no scan can make a diagnosis of cancer - it is stillnecessary to get a piece of it ("biopsy") for examina- tion under the pathologist's microscope.MRI can help direct the biopsy; today the commonest method used is a fine needle insertedunder exacting ("stereotaxic") direction.

The needle is placed through a small burr hole drilled in the skull, and guided into the tumor. Therate of complications of this "stereotaxic biopsy" is very low; the death rate ("mortality") fromthe procedure is less than 1%. MRI Scan of the Head is particularly useful for imaging the

posterior and lower portions of the brain - the cerebellum and brainstem. Small tumors may bedetected there that were invisible on CT Scan. MRI is excellent for designing radiation therapyfields to treat tumors; the MRI gives good indication of how much "margin" needs to be added tothe radiation field to treat possible cancer cells escaped from the tumor. An MRA (MagneticResonance Angiography) gotten at the same time as the MRI can help a surgeon determine thelocation and character of blood vessels within the brain, and clearly show abnormalities likeaneurysm. MRI of the Head may be periodically repeated after treatment to gauge the progress of therapy or detect a recurrence of cancer. It can be difficult to distinguish between recurrent tumor and changes in the brain due to aggressive treatment - a PET scan (discussed below) can usuallymake this important distinction.

MRI of the Spine - This test is routine when "epidural spinal cord compression" ("ESCC") issuspected. This just means that the spinal cord is being compressed, either by benign or cancerous conditions. Since the spinal cord transmits signals to the entire body below the neck,compression of it can cut off these vital signals. With partial and temporary compression (e.g.less than 24 hours) damage may be reversible, but with complete or long term compression lossof sensory and motor function will be experienced to all areas under the lesion. In a patient

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diagnosed with cancer, new back pain (especially in the upper midback or "thoracic" region) willindicate spinal cord compression due to tumor spread 60% of the time. If any patient comes tothe doctor with new back pain (the 2nd most common reason for doctor office visits in America)then the chance is 1 in 1200 that the cause is a new cancer in the spine. Cancer commonly firstspreads to the vertebral bodies, that is the skeleton of the spine, and afterward will compress thespinal cord proper.

The important aspect of spinal cord compression is quick recognition and treatment, to avoid permanent paralysis and loss of bowel and bladder function. MRI Scan is the definitive test tovisualize spinal cord compression. No other test can show the spinal cord and surroundingvertebral bones as clearly as MRI. Any small area(s) of compression is obvious on "lateral" MRIfilms, which show the spinal column as though one is looking through it from the side. MRI withcontrast lights up the fluid around the spine ("cerebral spinal fluid") and makes the cord eveneasier to see.

Other tests included in the complete report are on X-Rays, Computerized Axial Tomography (CTor CAT Scan), Magnetic Resonance Imaging (MRI), Ultrasound, Barium Swallow, Small Bowel

Follow Through, Lower Tract Studies, IntraVenous Pyelogram (IVP), retrograde urethrography,Venography, Lymphangiography, Pulmonary Function Tests, Angiography, Digital SubtractionAngiography (DSA), Myelography, Contrast Myelography CT Scan, Ventilation-Perfusion Scan("VQ" Scan), Pulmonary Arteriography, Nuclear Medicine Imaging Tests, PET Scans, BoneScans, Tagged Red Cell Study, Liver Spleen Scan, Indium Scan, Gallium Scan, Thallium Scanand Thyroid Scan.