Exploring MRI

resonance spectroscopy (HMRS) used in conjunction with MRI can aid radiologists in diagnosing breast cancer, which reduces the false positives and unnecessary biopsies. While MRI tells us about the suspicious lesions, MRS by detecting elevated choline tells us which are likely to be malignant. It measures the levels of choline compound in a lesion and identifies an active tumor.
MR spectroscopy should be incorporated in all routine breast MRI procedures, which will significantly decrease the need for biopsies.

MR cartigram of knee joint
The normal patellar articular cartilage is homogenous and smooth in contour demonstrating low signal on PD and conventional T2 weighted images performed on MRI. On SPGR with fat suppression, it is of uniform bright signal against the dark bone and marrow fat. High resolution T2 weighted images have shown zones of articular cartilage corresponding to collagen architecture.
Articular cartilage is considered to have four zones:
? Superficial zone which forms the articular surface of the joint.
? Larger transitional zone deep to superficial zone.
? Radial zone, which is the largest layer of articular cartilage, and thin calcified zone.

Cartilage changes in chondromalacia
Chondromalacia patella is loss of articular cartilage or degeneration adjacent to the medial facet, median ridge and lateral facet. It is one of the most common causes of knee pain in adolescents and young adults. The clinical symptoms and signs are non-specific in the early stages and diagnosis is often confirmed only by arthroscopy. In young patients, cartilage lesions unless diagnosed and treated may result in early osteoarthrosis. MRI with its excellent soft tissue resolution is the best imaging technique available for cartilage lesions.
There are four grades of chondromalacia with reference to outer bridge arthroscopy grading. In grade I chondromalacia, focal areas of increased signal intensity are noted. In grade II, there is
fissuring and fragmentation in addition to blister like swelling. Basal degeneration may be seen in association with surface fibrillation in grade III. A spectrum of grades of chondral loss is seen. Ulceration and exposure of subchondral bone in grade IV are depicted on MR images by frank articular cartilage defects, exposed subchondral bone and underlying fluid.

T2 mapping
Although cartilage appears relatively uniform on gross inspection, the orientation of collagen and the concentration of water, chondrocytes and proteoglycans varies across the thickness of the tissue. In early chondromalacia, there is an increase in chondral water content, alteration in collagen matrix and a depletion of proteoglycans, which causes an elevation of T2 values.
T2 weighted MR imaging can be used to depict the biochemical composition. T2 mapping is a quantitative approach to measure the T2 relaxation time generating a colour map. It provides information about cartilage permeability and break down in collagen structure. When collagen is destroyed, hydrogen dipoles become more mobile and T2 values increase, resulting in corresponding loss of stratification.
Standard sequences used in MRI for hyaline cartilage are not very sensitive in grade I and grade II. In these patients, cartigram is beneficial by showing increased T2 values and loss of normal stratification. By a clear list of indications and educating clinicians, it can become an important tool in diagnosis of early chondromalacia patella.