Don Rauf

MRI's changing status as an instrument for breast cancer diagnosis and evaluation was apparent last month at the 2008 American Society of Clinical Oncology meeting. One study suggested that MR's growing popularity for treatment planning may had led to more mastectomies, and another trial added to growing evidence about its ability to identify metastatic lymph nodes.

The mastectomy findings arose from Fox Chase Cancer Center in Philadelphia. Lead author Dr. Richard Bleicher, codirector of Fox Chase's breast surgery fellowship program, reported that women who received an MRI had an 80% higher chance of having a mastectomy rather than a breast-conserving lumpectomy. The findings were drawn from the medical records of 577 breast cancer patients, 130 of whom had MRIs prior to treatment. 

Bleicher believes the high number of false-positive findings associated with MRI may be leading to unnecessary breast removal. 

"Rather than have a biopsy to see if the MRI findings are real, women and their doctors may choose mastectomy out of an abundance of caution," he said in an interview. 

While some women will have cancer detectible only with MRI, Bleicher has seen an equivalent survival rate for patients who had mastectomies and patients treated with breast conservation and radiation. Bleicher and colleagues also found that MRI made no difference in giving surgeons a clearer picture of positive margins. 

"Our study doesn't change the American Cancer Society's recommendation for use of MRI," he said. "MRI just shouldn't be used as a knee-jerk response to breast cancer."

The chance that MRI provides meaningful results depends on the baseline characteristics of the patient, according to Dr. Allison Kurian, an assistant professor of medicine and of health research and policy in the divisions of oncology and epidemiology at Stanford University School of Medicine. 

"The question is how high risk is this patient to have another area of cancer somewhere that's getting missed by the mammogram? Screening with MRI only gets done in women who are above a certain risk because the feeling is that's the only time it's worthwhile to find extra [cancer]," she said.

Dr. Elizabeth Morris, director of breast MRI at Memorial Sloan-Kettering Cancer Center in New York City, agrees that breast MR should not be used as a knee-jerk method on anyone with cancer. She believes, however, that it should be part of a routine patient evaluation for treatment. 

Experience has taught Morris that MRI delineates the extent of the disease better than alternative imaging modalities. It provides an optimal view of the contralateral breast and, with some frequency, characterizes contralateral cancers when a known cancer is in the ipsilateral breast.

Improved MR spectroscopy and other technical advances are helping cut down on the incidence of false positives with breast MR, but more research is needed to refine its role in breast cancer diagnosis, Morris said. 

While Bleicher's study suggests that breast MRI may be leading to more mastectomies, a separate study from the Seattle Cancer Care Alliance and the University of Washington Medical Center also presented at the ASCO meeting found that breast MRI can be an alternative to exploratory surgery in helping women whose breast cancer has spread to their lymph nodes determine if they need radiation to treat the disease.

The retrospective study of 167 patients who underwent radiation therapy for invasive breast cancer after surgical staging of their tumors determined that the tumors' physiological information shown on MR scans correlated with surgically based findings of cancer having spread to lymph nodes. This suggests that breast MRI could help determine if women scheduled to undergo surgery will later need radiation therapy, according to lead author Dr. Christopher Loiselle, a resident in the radiation oncology department at Washington. 

"When you give chemotherapy first, and then perform the surgery to remove the cancer and sample the lymph nodes, you reduce your ability to know whether there was cancer in the axillary (underarm) lymph nodes before the patient was treated with chemotherapy," Loiselle said. "This raises the question: Is there another way to stage those lymph nodes? Our study showed that tumor characteristics as seen on an MR scan may be the answer."

For more information from the Diagnostic Imaging website:

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Articles

MRI’s changing status as an instrument for breast cancer diagnosis and evaluation was apparent last month at the 2008 American Society of Clinical Oncology meeting. One study suggested that MR’s growing popularity for treatment planning may had led to more mastectomies, and another trial added to growing evidence about its ability to identify metastatic lymph nodes.

Report from ASCO: Studies reveal pros and cons of breast MRI

Multislice CT angiography should be the preferred choice over MR angiography or duplex ultrasound for initial evaluation of patients with suspected peripheral arterial disease.

Dr. Rody Ouwendijk of the Erasmus University Medical Center in Rotterdam, the Netherlands, drew this conclusion from a four-hospital study involving 514 patients with arteriosclerosis in their lower limbs. Patients were randomly selected to receive CTA, MRA, and duplex ultrasound. The clinical and financial effects of the studies were evaluated six months later. 

 (2008:190:1349-1357), indicate that CTA and MRA were relatively equivalent to one another clinically and demonstrably better than duplex ultrasound. 

At an average cost of €104 per procedure, duplex ultrasound was less expensive than CTA (€163) or MRA (€472). 

The advantage shifted to CTA and MRA, however, when vascular radiologists and surgeons surveyed for the study had significantly more therapeutic confidence in those two modalities than duplex ultrasound. Within 60 days after initial testing, more additional vascular imaging tests were performed on the patients who had received duplex ultrasound first than on patients who were evaluated with CTA or MRA. 

No significant differences were seen in the number of additional tests for patients in the CTA and MRA groups or for quality-of-life measures for patients evaluated with any of the three modalities.

The potential for saving money with CTA led Ouwendijk and colleagues to recommend that modality, considering that its clinical performance was about the same as MRA and demonstrably better than duplex ultrasound. 

The main disadvantages of CTA, established in the published medical literature, are patient exposure to ionizing radiation, the use of potentially nephrotoxic iodinated contrast media, and the confounding effects of vessel wall calcifications on image intrepretation. 

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CTA beats MRA, ultrasound for early evaluation of peripheral arterial disease

No clear winner has emerged in a head-to-head comparison of whole-body FDG-PET/CT and whole-body 3T MRI for non-small cell lung cancer staging. Unenhanced PET/CT proved better for detecting metastatic lymph nodes and soft-tissue involvement, while MR was more sensitive to the presence of brain and liver metastases.

Although thoracic CT is considered the modality of choice for assessing the intrathoracic spread of lung disease, no consensus exists for which modality is best for evaluations of metastases.

Dr. Chin A. Yi and colleagues at the Sungkyunkwan University School of Medicine in Seoul, Korea, examined findings from 165 NSCLC patients screened with whole-body PET/CT and whole-body 3T MRI.

None of the patients were thought to have metastatic disease on the basis of a physical exam, lab findings, and enhanced thoracic CT covering the thorax and upper abdomen.

No statistically significant advantage was identified for either PET/CT and whole-body MRI for tumor staging. Whole-body PET/CT and 3T MRI correctly staged 82% and 86% of the primary tumors, respectively.

For N-staging, the performance of the two modalities was again nearly equal. PET/CT correctly staged 70% of patients, and 3T MR correctly staged 68%.

Both PET/CT and whole-body MR showed 86% accuracy on a per-patient basis for detecting metastases. PET/CT was 48% sensitive and 96% specific for their presence. Three-T MRI was 52% sensitive and 94% specific.

Yi and colleagues found that PET/CT may have been more useful for metastasis detection in lymph nodes and soft tissue because of prominent FDG uptake in lesions in these areas.

Yi credited the higher field strength of 3T MRI and the use of a phased-array cardiac coil for thoracic imaging for improvements compared with earlier studies performed with 1.5T MRI. The better contrast of the MR images compared with PET/CT may have provided improved metastasis detection in the brain, liver, and kidneys, he said.

Results were published in the August issue of 

For more information from the Diagnostic Imaging archives:

Whole-body MR with diffusion imaging matches PET/CT for lung cancer staging

Whole-body cancer staging in some requires frequent follow-up

Whole-body MRI and PET/CT can miss many metastates

Whole-body PET/CT and 3T MR perform equally well for lung cancer staging

A physiological reason may explain why the shrinking violet in your family is so shy. Using brain SPECT, Dutch researchers have detected irregularities in dopamine and serotonin neurotransmitter systems in the brains of such individuals that appear to be linked to social anxiety disorder, a condition that affects an estimated 15 million adults in the U.S. and frequently leads to alcoholism and depression. 

Dr. Nic J.A. van der Wee, a psychiatrist specializing in anxiety disorders and psychiatric neuroimaging, and colleagues at Leiden University in the Netherlands used a binding radioactive compound (123I-β-(4-iodophenyl)-tropane) as a tracer to visualize dopamine and serotonin transporters in the brain. The procedure was performed on 12 patients diagnosed with social anxiety disorder who had not taken medication to treat the condition and 12 healthy controls. 

In the patients with social anxiety disorder, SPECT revealed altered uptake activity in the thalamus, midbrain, and pons, areas known to be acted upon by serotonin, and in the striatum, an area known to be acted upon by dopamine. The significantly higher binding potentials found in the social anxiety disorder patients indicate imbalances that may affect the way their brains function in normal situations, causing anxiety.

"We found the first direct evidence for abnormalities of the brain's dopaminergic system in patients with social anxiety disorder," said van der Wee. "The study demonstrates that social anxiety has a physical brain-dependent component."

One unique aspect of the research was that it included only patients without prior exposure to pharmacotherapy. 

"Our findings broaden the neurobiological model of social anxiety disorder and may lead to novel research not only in pharmacotherapy but also in the etiology of the disorder," van der Wee said. 

The study was published in the May issue of the 

The Netherlands team conducted the research with SPECT, citing that it is easy to use and does not require extensive facilities to produce the radioactive compound. Compared with PET, SPECT offers a higher patient comfort level, lower cost, and higher safety index, according to van der Wee. 

Van der Wee and his team are expanding on their research as part of the large-scale Netherlands Depression and Anxiety Study. It is examining 3000 subjects, including patients with social anxiety disorder. The effort will feature a structural and functional brain imaging study using novel MRI techniques in a subset of 300 patients, including patients with society anxiety disorder. 

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