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Microscopy coils provide SNR to resolve smallest anatomy

Best Practice
Kurihara, Yasuyuki, M.D. Kawasaki, St. Marianna University Japan
Van Cauteren, Marc, Ph.D. Philips Healthcare Japan
Kooi, Marianne Eline, Ph.D. Maastricht University Medical Center Netherlands
Obradov, Marina, MD Nijmegen, St. Maartenskliniek Netherlands
Grainger, Andrew Leeds General Infirmary United Kingdom

 

Two Microscopy coils are available for Achieva and Intera scanners, with inner diameters of 23 mm and 47 mm. These coils are designed for applications requiring high spatial resolution in small fields-of-view. Microscopy coil applications include studies of the skin, eyes, small joints, superficial vessels, nipples and a variety of pediatric examinations. This article presents some examples contributed by our users demonstrating that the Philips Microscopy coils provide outstanding SNR and superb in-plane resolution to depict pathological features or subtle degenerative changes.

Exploring osteoarthritis origins in fingers with 23 mm coil

The 23 mm Philips Microscopy coil provides the SNR and small FOV necessary to resolve tiny ligaments and cartilage structures in the fingers, in research studies at Leeds Teaching Hospital, United Kingdom. Investigators are attempting to detect the earliest degenerative changes associated with osteoarthritis (OA).

 

T1-WATS Normal articular cartilage and tendons.PD-weighted Collateral ligaments are visible.
T1-WATS
PD-weighted
Normal articular cartilage and tendons.
Collateral ligaments are visible.

"It's becoming increasingly obvious from [conventional coil] studies of osteoarthritis origins in the knee, for example, that there is much more going on than just cartilage loss - there is an inflammatory element or synovitis involved," says Andrew Grainger, M.D., consultant musculoskeletal radiologist. "We're quite excited at the moment, because in Microscopy coil studies we've seen a degenerative thickening of ligaments as a very early observation in osteoarthritis of the fingers."

 

Investigators are using a seven-sequence protocol combining T1- and T2-weighted images, post-contrast T1-weighted images, and T1-weighted WATS (using ProSet fat suppression) sequences to obtain images depicting finger ligaments, synovium and cartilage in three planes. A 40 mm FOV is used, producing images with an in-plane resolution of 0.2 mm2. The coverage obtained allows imaging of either the proximal or distal interphalangeal joint and the periarticular structures, such as tendons and ligaments.

 

The clinical research study has enrolled 70 subjects to date, including young and elderly subjects with and without osteoarthritis in the fingers. "We hope this research will ultimately help us find ways to address the cause of osteoarthritis rather than just treating the symptoms," he says.

 

The microcoil research into OA was funded by a personal grant to Prof. D. McGonagle from the Medical Research Council, UK.

 

 Patient with severe OA showing
soft tissue swelling dorsally,
causing bulging of the extensor
tendon (arrow). Note a dorsal
osteophyte (black arrowhead)
and loss of cartilage on the volar
aspect of the joint (white arrow). Distal interphalangeal joint in
patient with OA. Gross
ligament abnormality and
erosion in the intermediate
phalanx. Proximal phalanx at level of
proximal interphalangeal joint
in patient with OA. A large
erosion is seen.
Patient with severe OA showing soft tissue swelling dorsally, causing bulging of the extensor tendon (arrow). Note a dorsal osteophyte (black arrowhead) and loss of cartilage on the volar aspect of the joint (white arrow).
Distal interphalangeal joint in patient with OA. Gross ligament abnormality and erosion in the intermediate phalanx.
Proximal phalanx at level of proximal interphalangeal joint in patient with OA. A large erosion is seen.

 

 

Wrist and knee joints benefit from high resolution coil studies

Radiologists at St. Maartenskliniek (Nijmegen, The Netherlands) are using their Philips 47 mm Microscopy coil in routine clinical practice to produce high resolution images of the bone and ligaments in the wrist.

 

 

SE T1 HR 3D WATS
SE T1 HR
3D WATS

Coronal 47 mm Microscopy coil images of wrist ligaments aquired

in routine clinical practice.

 

TSE T2 SPIR
TSE T2 SPIR

Coronal 47 mm Microscopy coil images of wrist in a patient with

a scaphoid fracture.

 

 

In addition, they have been evaluating the coil's utility in studies of the patellar and trochlear cartilage. Using B-FFE and B-TFE sequences, radiologists are obtaining high-resolution images of patellar cartilage that enable them to characterize the nature and severity of chondral defects. Differentiating between partial and full thickness defects, and surface or deep ulcerations helps guide decisions on treatment, says Marina Obradov, M.D., St. Maartenskliniek radiologist. The center has used the coil in clinical studies for about a year.

 

St. Maartenskliniek radiologists are also engaged in studies of the femur's trochlear cartilage of patients with knee osteochondral transplantation, a procedure that St. Maartenskliniek orthopedic surgeons have performed on 14 patients so far.

 

"Using the Microscopy coil seems to be the most appropriate way to visualize and estimate incorporation of the osteoperiostal transplants in the trochlear cartilage," Dr. Obradov says. This method shows the best correlation with clinical findings and isotopic scans. "We image it with knee flexion with the coil directly on the trochlea and are able to acquire highresolution images."

 

Post-traumatic cystic lesion with subchondral edema.

B-FFE B-FFE
B-FFE
B-FFE
B-TFE B-TFE
B-TFE
B-TFE

The B-FFE images (top) show superficial cartilage ulcerations

and fissure defects. FOV 80 mm, matrix 512, 0.75 mm slices.

The B-TFE images (bottom) show cartilage thickening and

surface defect.  FOV 125 mm, matrix 512, 1.5 mm slices.

 

Coil focuses on vulnerable carotid plaques

Vulnerable carotid plaques are characterized by a thin fibrous cap and a large lipid pool, features that clinicians need to distinguish to make a reliable diagnosis. Eline Kooi, Ph.D., Medical Physicist in the Department of Radiology, and her colleagues at the University Hospital Maastricht, The Netherlands, are using the 47 mm diameter Philips Microscopy coil to obtain striking images of these plaques.

 

Using proton-density and T1- and T2-weighted sequences and a black blood imaging technique - to avoid plaque-mimicking artifacts of the blood - investigators have exploited the coil's SNR to enable 0.3 x 0.3 mm2 in-plane resolution. Scan times have been about 3:09 min. for nine 2.5 mm slices. The small size of the surface coil prevents fold-over artifacts despite the small (70 mm) FOV. Since 2000, Dr. Kooi and her co-investigators have studied 72 patients, who present with symptoms, such as one or more TIAs or minor strokes. The results of this study are currently in press.

 

 T1-weighted TSE image of the common carotid artery of a healthy volunteer.   Atherosclerotic plaque with intraplaque hemorrhage in the common carotid artery.
T1-weighted TSE image of the common carotid artery of a healthy volunteer.
Atherosclerotic plaque with intraplaque hemorrhage in the common carotid artery.

MR mammary ductography helps reveal small intraductal lesions

MR ductography is a promising alternative to conventional ductography for women experiencing nipple discharge, says Yasuyuki Kurihara, M.D., (St. Marianna University School of Medicine, Kawasaki, Japan) who is investigating the MR technique together with the MR Clinical Science team of Marc Van Cauteren, Ph.D., PMS Asia-Pacific.

 

Conventional ductography MR ductography High-resolution T1-weighted 3D FFE with CLEAR and ProSet fat suppression, voxel size 0.15 x 0.3 x 0.8 mm3.
Conventional ductography
MR ductography
High-resolution T1-weighted 3D FFE with CLEAR and ProSet fat suppression, voxel size 0.15 x 0.3 x 0.8 mm3.

"In conventional ductography, a tube is inserted into the fine mammary ducts to inject contrast material, the most common procedure in Japan to evaluate nipple discharge, which is seen in 5-7% of all patients with breast disease," Dr. Kurihara says. "While this technique is highly sensitive for intraductal lesions, it is invasive, timeconsuming and painful. MR ductography could be a more desirable option."

 

So far, 15 women with nipple discharge have undergone MR ductography, using the 47 mm Microscopy coil. "We could visualize ducts of 0.8-22.1 mm in size and demonstrate intraductal tumors of 1.0-5.6 mm," Dr. Kurihara notes. Conventional ductography performed in 10 of the 15 patients helped detect seven intraductal tumors. MR ductography confirmed this finding and allowed detection of an additional intraductal tumor that was not seen on conventional ductography.

 

"Our early conclusion is that MR ductography is painless, fast and helps detect intraductal lesions with good reliability in this class of patients," Dr. Kurihara says.

 

T1-weighted MR ductography of an intraductal papilloma.MIP MR ductography of an intraductal papilloma.
T1-weighted
MIP
MR ductography of an intraductal papilloma.
MR ductography of an intraductal papilloma.


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Best Practice
Achieva 1.5T, Intera 1.5T
Body, Breast, Extracranial MRA, Knee, Musculoskeletal, Oncology, Vascular, Women's health
 

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