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NIC, Las Vegas, highlights 3.0T quality and applications

Best Practice
Orrison, William Las Vegas, Nevada Imaging Centers USA
Gibson, Jon Las Vegas, Nevada Imaging Centers USA

According to William W. Orrison, M.D., Nevada Imaging Centers (NIC, Las Vegas, Nev., USA), referring physicians and patients alike prefer and seek out the high quality healthcare providers in any given market.This belief drove Dr.Orrison's strategy for NIC's Spring Valley clinic, which acquired a Philips 3.0T (Intera) system in 2004. Instead of using the 3.0T system's power to boost throughput, Spring Valley harnesses the 3.0T to create superb images and conduct advanced studies.Today, Spring Valley is an economically viable clinic performing the most sophisticated studies available, such as diffusion tensor imaging (DTI), MR spectroscopy (MRS) and BOLD fMRI. It has seen significant gains, especially, in spinal cord and brain multiple sclerosis imaging.

 

 William W. Orrison, M.D.  Nevada Imaging Centers, Sping Valley clinic Jon Gibson, MR Technologist
William W. Orrison, M.D.
Nevada Imaging Centers, Sping Valley clinic
Jon Gibson, MR Technologist

 

Whether performed at a 0.2T or 3.0T field strength, U.S. health insurance companies reimburse MR scans at the same level. Accordingly, many clinics improve their cost-benefit ratio by acquiring a relatively cheaper low field system and scanning as many patients as possible. Some might regard Nevada Imaging Centers' (NIC) strategy to purchase a more costly 3.0T system as economically counterintuitive. NIC radiologist, Dr. William Orrison, however, had a vision for the 3.0T: calculate a reasonable patients-per-day goal and then maximize the 3.0T system's advanced imaging capabilities to attract patients and referring physicians.

 

"Three years ago I believed 3.0T was ready for outpatient operation and I wanted to prove that," Dr. Orrison says. "Secondly, I thought 3.0T would raise the overall quality of healthcare and attract both patients and referring physicians."

 

Dr. Orrison's 3.0T conviction was reinforced after seeing 3.0T images at Philips' RSNA exhibit in 2003 and test-running 3.0T techniques at Philips' Cleveland facility. After evaluating several vendors' products, NIC radiologists chose the Philips 3.0T system based on Philips' excellent uptime, service and support. It became operational in May 2004 at NIC's new Spring Valley clinic.

 

NIC's 1.5T Philips system has provided 100% uptime, Dr. Orrison notes. "Plus, Philips service has been phenomenal. The third reason for selecting Philips is that we have an extremely supportive Philips representative."

 

While Dr. Orrison believed in the technological excellence of Philips MR systems, keeping a 3.0T system up and running was the most critical issue. NIC calculated a pro forma that dictated a break-even mark of 20 patients per day. Today, the system exceeds that goal by five patients, reducing NIC's initial seven-year projected return-on-investment to four years.

 


  9-year-old male with post-inflammatory encephalomalacia

  The axial FLAIR sequence demonstrates bilateral parietal encephalomalacia with decreased

  signal intensity (arrow). Diffusion tensor imaging (32 directions) with fiber tracking

  demonstrates marked loss of superior cortical spinal tract fibers in the region of encephalo-

  malacia identified in the FLAIR image. The images were acquired using the SENSE Head coil.

FLAIR GRASE Fiber tracking
FLAIR
GRASE
Fiber tracking

 


Focus on advanced applications

Spring Valley specializes in a wide range of neuro MRI cases, and adding the 3.0T system - to NIC's complement of 0.3T, 0.7T, 1.0T and 1.5T scanners (five total) - has opened the door to additional sophisticated studies, which demand high SNR for higher resolution and/or thin slice imaging.

 

The most significant difference between Spring Valley and NIC's four other imaging centers is a marked increase in the diagnosis of spinal cord multiple sclerosis. "We make that diagnosis daily now," he says. "Working at 1.5T, I might have made it monthly, possibly weekly at most."

 

Similarly, brain MS studies are considerably more sensitive at 3.0T, greatly increasing clinicians' diagnostic confidence. "I find brain MS lesions that I would have difficulty finding or not finding at all at 1.5T, due to noise, artifacts or insufficient resolution," Dr. Orrison says. "The Philips 3.0T system has reduced lesion subtlety, improving visualization and enabling us to confidently call abnormal lesions."

 

Clinicians have been noting that 3.0T helps better to detect MS lesions than 1.5T, Dr. Orrison observes.1 Spring Valley achieves its MS imaging results using conventional T1- and T2-weighted sequences, FLAIR, DTI (white matter) fiber tracking, MR spectroscopy and SENSE and now preferentially conducts MS studies on the 3.0T system.

"SENSE buys us time"

Spring Valley uses SENSE factor 1.6 (i.e. exactly 1.6 times faster scan time than without SENSE) on MS exams and nearly all other studies to afford increases in matrix or number of signal averages, while avoiding raising scan time.

 

"We could run this system like a fast 1.5T scanner as some centers do, but instead we use it specifically to make more difficult diagnoses," Dr. Orrison notes. "A significant percentage of patients we see here have failed a diagnosis elsewhere, so we use the scanner at its maximum capability rather than maximum throughput. We concentrate on high quality and accept that it will take longer. SENSE allows us to keep a higher matrix and more signal averages, so we can acquire a higher quality scan in the same or less time. SENSE buys us time."

 

 


  33-year-old female with multiple sclerosis

  The sagittal T2-weighted image demonstrates focal abnormal signal intensity within the

  cervical spinal cord (arrow). The sagittal STIR sequence demonstrates two focal areas of

  abnormal increased signal intensity within the cervical spinal cord (arrows). The axial

  T2-weighted image demonstrates a focal area of abnormal signal intensity centrally within

  the spinal cord (arrow). The images were acquired using the SENSE NeuroVascular coil.

T2-weighted STIR T2-weighted
T2-weighted
STIR
T2-weighted

 

 


  22-year-old male with left visual field defect and left optic

  nerve glioma.

  The coronal T2- weighted GRASE demonstrates focal abnormal

  signal intensity within the left posterior prechiasmic optic nerve.

  The coronal post-contrast T1 SE demonstrates peripheral contrast

  enhancement in the focal left prechiasmic optic nerve mass. The

  images were acquired using the SENSE Head coil.

GRASE Post-contrast
GRASE
Post-contrast

 


 

MR spectroscopy helps to evaluate MS lesions

Spring Valley is exploiting the advantage that higher field strength brings to MR spectroscopy for evaluating the levels of nacetyl aspartate (NAA), choline and creatine in MS lesions. Differences in metabolic levels are seen between active and inactive MS plaques and between MS lesions and tumors.

 

"In an active lesion, NAA is usually more normal, choline is elevated and creatine is decreased. In addition, you may see also see elevated lactate and lipids," he says. "Inactive MS plaques normally have an elevated myoinosotol level and the choline, creatine and NAA are typically more normal."

 

"Depressed NAA levels are usually associated with neoplasms," he adds. "If the NAA is normal, we're reasonably confident it's not a tumor."

 

"MR spectroscopy represents a technique we don't perform at 1.5T for the simple reason that we have 3.0T," he continues. "Three Tesla gives us tremendously better spectroscopic data across the board and takes significantly less time."

DTI fiber tracking's many applications

MS cases have benefited from Spring Valley's use of DTI fiber tracking, as have other indications involving white matter, including dementia, head trauma, stroke and pre-surgical brain tumor evaluation. At press time, Spring Valley had performed DTI scans for a total of 165 patients, currently conducting 5 to 10 cases weekly.

 

In MS cases, DTI is used to depict pathology and the three-dimensional nature of white matter fiber tracts. "Clearly, a major goal is to diagnose MS earlier to facilitate earlier treatment," he says. "It may also afford a better way to track a patient's response to therapy."

 

In head trauma cases, DTI can help doctors determine disruption of white matter fiber tracts, such as that wich might occur in a rear-end automobile collision, in which an occupant in the lead vehicle may have suffered a shearing injury of the fiber tracts.

 

DTI also helps Spring Valley radiologists evaluate different types of dementia, based on fiber tract loss. Different dementias impact different brain regions; Alzheimer's disease affects parietal and temporal brain areas, while the frontal and temporal lobes are primarily impacted in frontotemporal dementia. "We have been correlating marked decreases in fiber tracts in areas of the brain affected by a particular type of dementia," Dr. Orrison says.

 

Stroke can disrupt white matter fiber tracts, so Spring Valley employs DTI to isolate affected tracts. While both 1.5T and 3.0T platforms are comparable in general stroke MRI, Dr. Orrison says, the 3.0T system excels in defining brain stem strokes and small strokes.

Philips 3.0T impresses referring physicians

"A referring neurologist who attended the American Academy of Neurology meeting told me he didn't see anything there that was as up-to-date or impressive as the work we're doing," Dr. Orrison relates. "A local neurosurgeon also said it's important for people to know that world-class imaging is available in Las Vegas."

 

More neurosurgeons are referring to Spring Valley, he adds, based on the facility's MR spectroscopy, DTI, CSF flow and BOLD fMRI. Spring Valley performs two to three BOLD fMRI cases per week, including research on normal patients and also patients suffering from stroke, hearing or vision loss and head trauma. BOLD fMRI also is employed in studies of language dominance and for surgical planning of tumor resections.

 

 


  Head trauma

  The axial FLAIR image demonstrates focal encephalomalacia in

  the right frontal cortex secondary to prior head trauma. The

  coronal T2-weighted image demonstrates right inferior frontal

  and left superior frontal "coupe-contrecoup" injury from head

  trauma. The axial T2-weighted GRASE sequence demonstrates

  right frontal encephalomalacia secondary to head trauma.

  fMRI demonstrates significantly decreased cortical activity on

  the right following motor activation task. The images were

  acquired using the SENSE Head coil.

FLAIR T2-weighted
FLAIR
T2-weighted
GRASE fMRI
GRASE
fMRI

 


 

Independent imagers contribute to 3.0T clinical knowledge

While Spring Valley has demonstrated the feasibility of operating a 3.0T system in the outpatient environment, bringing high quality, advanced imaging to the community is only half of the story. Increasingly, centers like Spring Valley are conducting 3.0T clinical trials that will inform 3.0T diagnostic knowledge and shape utilization.

 

"We don't necessarily scan more patients, just more of a given type of patient. While tertiary centers don't get high volumes of routine cases, we may get thousands of those in a few months," Dr. Orrison explains.

 

"It may take these sites a long time to accumulate a healthier, more routine patient group for a study. Our patients are relatively healthy patients who can participate easily in studies, allowing us to get clinical trials done faster."

 

Spring Valley's first large patient study will ultimately recruit 50 to 100 patients with multiple sclerosis to evaluate certain imaging aspects of DTI. "We hope to share the results with other 3.0T users as quickly as possible," he says.

Reference:

1. Bachmann, R, Reilmann, R, Kraemer, S, et. al.

    Multiple Sclerosis: Comparative MR-Imaging at 1.5 and 3.0 Tesla.

    Scientific Papers (RSNA): Dec. 5, 2003.

 

 

 

Photo of Dr. Orrison by MichaelG.org



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Best Practice
Intera 3.0T
Release 10, Release 11, Release 9
Master / Quasar Dual
Brain, Brain stem, Cervical spine, Neck, Neuro, Perfusion, Spectroscopy, Vascular
 

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