Pioneers of MRI in India

Functional MRI (fMRI) measures signal changes in the brain that are due to changing neural activity and is also referred to as BOLD imaging (Blood oxygen level dependent).

A person's brain is scanned while he or she is performing a certain physical task such as squeezing a ball or looking at a particular type of picture. When the neural activity is increased, there is increase in oxygen demand and the vascular system actually overcompensates for this, increasing the amount of oxygenated hemoglobin relative to deoxygenated hemoglobin.

Such techniques are being used in pre-surgical planning and in basic neuroscience research in areas such as memory, expressive and receptive speech, visual spatial processing and other cognitive processes

Diffusion weighted images are very commonly used in the assessment of acute stroke and are also widely used in oncology.

Diffusion Tensor Imaging , also known as MR Tractography non-invasively maps white matter tracts. Diffusion parallel to nerve fibers has been shown to be greater than diffusion in the perpendicular direction. This provides a powerful tool to study in vivo fiber connectivity in the brain in a noninvasive manner and preoperative planning of resectability of brain tumors. Application of this technique to stroke, Alzheimer's disease and pediatric brain development are being investigated.

MR angiography is used to generate pictures of the arteries to detect any abnormal narrowing/dilatation or abnormal arterio-venous connections. MR angiography is often used to evaluate the arteries of the neck and brain, the thoracic and renal arteries and the arteries of legs. Magnetic Resonance Venography (MRV) is a similar procedure used to image veins.

MR spectroscopy is a noninvasive method providing metabolic information about the brain. MR spectroscopy enables tissue characterization on a biochemical level surpassing that of conventional MR imaging. MR spectroscopy is also able to detect abnormalities that are invisible to conventional MRI because metabolic abnormalities often precede structural changes.

MR defecography is technique to study disorders of ano-rectal function. It is indicated in patients having constipation, rectal incontinence, painful defection and rectal prolapse.. It permits analysis of the ano-rectal angle, opening of the anal canal, function of the puborectalis muscle and descent of pelvic floor during defecation. It provides good demonstration of the rectal wall, intussusception, enteroceles and rectoceles with excellent demonstration of the perirectal soft tissue. It allows assessment of spastic pelvic floor syndrome and descending perineum syndrome. No radiation hazard is associated with this procedure as was there in fluoroscopic x ray defecography. Images are obtained with patient at rest, at maximal sphincter contraction, during straining and during defection.

Although X-Ray Mammography remains the primary imaging modality in the evaluation of breast disease, the mammogram can at times be inconclusive for the presence or location of an abnormality. MR imaging has been used as an adjunct to mammography, particularly for patients with equivocal mammographic findings. The main advantage of breast MR imaging is its high sensitivity, with reported sensitivities for cancer ranging from 91% to 100% with varying specificity. Multiple investigators have shown that MR mammography may be useful to verify multifocality and multicentricity of breast cancer, differentiate scars from recurrences after breast-conserving therapy, screen high-risk groups who have a family history of breast cancer, investigate breast implants, examine breasts in cases of histologically proven breast cancer, metastasis with unknown primary