Imaging aids dermatologists in diagnosis, treatment

Stanford, Ca. - Imaging can help dermatologists to diagnose and treat some of the lesions they encounter, according to Barton Lane, M.D., professor of radiology and neurosurgery at Stanford University Medical Center, here.

He notes that the following common lumps and bumps may be visible by imaging: lipoma, dermoid, basal cell cancer, squamous cell cancer, hemangioma, nasal glioma, meningioma and sacral decubitus.

Because imaging technology is constantly changing, Dr. Lane recommends that dermatologists keep up-to-date on what is available.

It can also be used for body imaging to look for metastatic disease.

Plain films can be used to examine the chest, bone and acute abdomen, while sonography is used for cardiac, carotid, obstetric, head and neck and liver lesions.

Doppler ultrasound can be useful in the evaluation of deep vein thromboses and echocardiography. Color flow Doppler imaging can be used to look for metastatic lymph nodes.

X-ray uses a beam of high-energy photons, and is differentially absorbed by different tissues. The kilovoltage can be adjusted for penetrating power, and it is the basis for standard radiography and CT, Dr. Lane says.

There are two types of contrast imaging: iodinated and MRI. Iodinated contrast is used for X-ray and CT. Contrast imaging can be used to characterize tumors, infections and vascular lesions. It is also useful for neuroradiology and body imaging.

Multidetector CT (MDCT) provides imaging of thin slices (less than 1 mm) of tissue, and it has the following benefits:

"We literally use it from head to toe. It is very rapid acquisition, and it gives you a lot of information," Dr. Lane says.

For an MRI examination, patients are placed in a static magnetic field and are subject to a series of radiofrequency waves and changing magnetic fields called gradients. Molecules and atoms are stimulated, and on relaxation, information is generated. A series of data acquisitions called sequences is acquired. Data acquisition is predetermined according to suspected diagnosis and body part. Up to 15 sequences may be necessary for any one exam. For example, a routine spine exam is five sequences, and an acute stroke exam is up to 15 sequences.

MRI is somewhat similar to CT in that it is used to characterize some skin lesions and also to see how deep they go. It can determine whether the disease involves the lymph nodes, and it is useful for dermatologists to establish the depth of invasion as well as whether other body structures are involved.

PET and PET/CT can be used for cancer detection. "PET/CT is the hottest new thing," Dr. Lane says. "Everyone seems to have a PET/CT now. It is used in melanomas and other kinds of squamous cell cancers, mostly for staging and following therapy."

Imaging applications for dermatologists Imaging has the following applications in dermatology:

When in doubt, Dr. Lane encourages dermatologists to consult a radiologist.