News & Articles

All articles are taken from online sources and are not written by ADG staff.

Chest CT a handy adjunct to breast MR

7/11/2007
By: Eric Barnes

Dedicated breast CT scanners aren't on the market yet, or even close to market, truth be told. But breast CT happens every day -- with every chest and cardiac CT exam -- and it's the radiologist's job to read the scan for the frequent incidental findings it can yield. CT can even be used to guide breast intervention in some cases.


"Every chest CT is a breast CT," said Dr. Jeffrey Mendel, in a talk at the 2007 International Symposium on Multidetector-Row CT sponsored by Stanford University. Mendel is chief of radiology at Caritas St. Elizabeth's Medical Center in Boston. He reminded his audience to look at the edges of CT scans to pick up lesions that might otherwise be missed. Multidetector-row CT (MDCT) actually does a good job of detecting breast lesions, Mendel said. It allows for very thin (1-mm thick) images of the breast so that even small, radiographically visible lesions can be detected on CT.

On the other hand, "only 85% of the breast tissue is visualized on the standard screening mammogram, and ... with breast implants in place that may drop 75% or even 70%," Mendel said. "Many patients coming to you for a CT scan may be ill enough that they haven't had their routine screening mammogram. My mentor ... taught me that we're responsible for the corners of the film, and ... to look at the periphery of the chest and look for the breast tissue."

When examining breast tissue, Mendel said radiologists should look for the following:

• Masses or areas of focal asymmetry Focal skin thickening Architectural distortion
• Radiating spicules reaching to a mass
• Architectural distortion
• Radiating spicules reaching to a mass

There's no urgent need to look for microcalcifications, since most are too small to pick up on the average CT scan, Mendel said. But incidental breast carcinomas are found frequently. Mendel said his facility detected four during a typical three-month period last year.

CT intervention

Along with examination of breast data, there are good reasons to perform CT-guided breast intervention, Mendel said. First, if the facility performs breast MRI, it may encounter technical problems that prevent the completion of some MR-guided biopsies. Among the challenges of MR-guided breast biopsy is that lesions near the chest wall or medially located are very difficult to biopsy with a grid-based technique, he said. The patient has to lie prone for long periods of time, and it's very difficult to monitor and sedate patients in the MR environment. Also, some incidental breast lesions seen on CT are not visible using MRI or ultrasound." In a lot of tertiary care centers, the people who do mammography don't do CT, and they're not really familiar with the capabilities of our MDCT scanners," Mendel said. "So if you think about it, you may find (CT) a nice adjunct to your practice." Two interventional procedures that are easily performed with a CT scanner are:

1. Core needle biopsy -- for patients who can't be safely imaged with MRI, or simply can't tolerate the longer scan times associated with MR-guided breast biopsy
2. CT-guided needle localization for surgical incision -- a good choice for lesions that can only be seen on MRI or CT

Certain locations, such as the chest wall, posterior breast, and subareolar, or superficial lesions that cannot be accessed with MR are better performed with CT, Mendel said. A typical patient presented with an enhancing lesion in the axillary tail -- so far back it was inaccessible to the biopsy grid, Mendel said. She was given contrast to enhance the lesion, turned on her back, and with CT and a thin needle for guidance the lesion was easily excised and a hematoma aspirated, in about 20 minutes with iodinated core biopsy. During biopsy it's important to place a small metallic marker to allow for future needle localization, he said. Many MR-detected lesions are small and may be completely excised during the biopsy procedure. Also, do a post-procedural CT scan to ensure that the marker is actually where the lesion was, Mendel advised. This should be followed by a post-procedural mammogram to see if the marker is visible on mammography, and to make sure the marker hasn't moved. The CT scanner is also a great tool for some body biopsies, he said. CT's advantages include supine positioning and easy patient positioning, Mendel said. With CT, "you can lift the arm up or down, draw blood, you can get access to lesions, you can sedate and monitor your patients easily, and the ultrasound machine doesn't get dragged into the bore of the magnet if you try to put the patient through a CT scanner," he noted. A challenge of CT is that the breast moves a bit. And although the technique is very straightforward, it is uncommon and so requires a little planning. The slice thickness depends on lesion size; Mendel said his facility typically uses 3-mm-thick slabs. The dose can be cut fourfold by reducing the kVp to 90 without reducing mAs, he said. Contrast is not always necessary -- for example, when looking for parenchymal asymmetry seen on mammography. If contrast is administered, look for early enhancement along ducts, or areas of irregular enhancement, Mendel said. CT can't perform as thoroughly as a full kinetic MRI study with five to seven phases, he said, but with contrast it's usually sensitive enough to find out what's going on in the breast.

Remember to look at the breast in CT data, and use it for problem solving, he said. "If you don't think about breast CT, you're not going to see the incidental lesion, and you're not going to be able to use it for intervention."

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7/4/2007
By: Heather Hokenson

You could say it's the oldest open "cold case" to date -- the death of the famous Alpine glacier iceman. Since he was discovered in 1991 near the Italy-Austria border, his 5,300-year-old mummified remains have been subjected to numerous scientific tests, and theories have abounded as to how he died. Recently, however, a team of Italian and Swiss researchers determined the iceman's exact cause of death using multidetector-row CT (MDCT).

The iceman, known as Ötzi for the Ötztal Valley region where he was discovered, is considered to be the oldest and best-preserved human mummy. Found half-buried in ice by a German couple hiking in the Alps, the corpse was at first believed to be that of an unfortunate modern-day mountain climber. Local officials and a rescue team proceeded to dig him out of the ice (no doubt horrifying crime scene investigators had they been there), and only after examination by an archaeologist was Ötzi's true prehistoric age revealed. From 1991 to 1998, his remains were housed and studied at the University of Innsbruck in Austria. But after a custody battle of sorts, it was determined that Ötzi was discovered in Italy, and ownership was given to the government of South Tyrol, Italy. Ötzi currently resides in a temperature- and humidity-controlled refrigerated chamber on exhibit at the South Tyrol Museum of Archaeology in Bolzano, Italy. The study and imaging of Ötzi began with an international team of scientists and researchers from the University of Innsbruck, University of Vienna in Austria, Washington University in St. Louis, University of Texas M. D. Anderson Cancer Center in Houston, and General Regional Hospital in Bolzano, Italy.

Scientific wonder

Since his discovery, Ötzi has fascinated the scientific community, as his body was found frozen and well-preserved. The clothing he wore at the time of his death also survived, as well as his tools and other accoutrements, giving scientists a glimpse into life during the Neolithic-Copper Age. Clothing items found include his goat-hide coat and leggings, leather loincloth, calf-leather belt with a pouch, bear- and deerskin shoes stuffed with hay, bearskin cap, and remnants of an Alpine grass cloak. He also had with him a backpack frame, copper-blade axe, quiver and arrows, unfinished bow, flint, dagger, grass net, and even a "medicine kit" of birch polyporus, perhaps for its antibiotic and styptic properties.

From head to toe, Ötzi has been subjected to numerous tests, including Raman spectroscopy and chromatography of his skin, electron microscopy of lung particles, bone scans, and DNA testing, by scientists across the globe. His skull has been studied and reproduced with CT-guided stereolithography. Using 3D computer-assisted biopsy, samples were taken from his nose, maxillary sinus, and larynx. Other samples of his ribs, blood vessels, liver, spleen, diaphragm, femoral muscle and nerve, and brain were taken endoscopically. The contents of his stomach and colon were examined -- his last meal consisted of red deer meat and grains. Even the construction and materials of his footwear have been studied, inspiring modern reproductions. After all this examination, researchers believe Ötzi died at the approximate age of 45. He weighed about 99 lb and stood about 5 feet, 2 inches tall (Experimental Gerontology, November-December 1998, Vol. 33:7-8, pp. 655-60).

Imaging the iceman

As imaging technology has evolved, so has the imaging scans that the iceman has undergone.

In 1991, the mummy was scanned with conventional CT (Somatom Plus, Siemens Medical Solutions, Erlangen, Germany) with sections of 1-8 mm. In 1993, the remains underwent CT scanning again, but this time with a portable unit to limit time in transit and to minimize thawing. A spiral CT scanner (Somatom Plus 40, Siemens) was used in 1994 in Austria and again in 2001 in Italy, and digital radiography was also used in 2001."In all, 38 radiographic and approximately 2,190 CT source images were obtained for interpretation. Many two- and three-dimensional reconstructed images were derived from the CT datasets. These were used to gain additional anatomic perspective and to aid anthropologists and other investigators in their studies," wrote Dr. William Murphy Jr., from the division of diagnostic imaging at the M. D. Anderson Cancer Center in Houston, and colleagues (Radiology, March 2003, Vol. 226:3, pp. 614-629).Besides the injuries that occurred from being frozen beneath a glacier for ages and dug out of the ice with tools such as ice axes, ski poles, sticks, rocks, and a pneumatic jackhammer, Ötzi was shown to have healed rib fractures of the fifth through ninth ribs on his left side, degenerative arthritis in his spine and left hip, and vascular calcifications in the carotid arteries, distal aorta, and right iliac artery -- not to mention a case of frostbite on his left little toe. However, "bone mineral content was excellent, and the lower-extremity long-bone cortices were particularly thick," Murphy's group wrote. "Thick cortices were associated with prominent nutrient canals and attachments for muscles (linea asperae) and tendons (tibial tubercles)." A life spent climbing and hiking in the Alps favored the development of muscle and bone, they explained.A common theory as to how Ötzi died was that he got caught in a storm and froze to death. But the 2001 digital x-ray findings suggested otherwise. X-rays of the ribs showed an arrowhead lodged between the rib cage and left scapula, indicating that he had been shot in the back and leading researchers to re-examine previous CT images.

The CT images also displayed hyperattenuating areas that were interpreted as dehydrated remnants of a hematoma, as well as evidence of a perforation of the scapula, the researchers stated. After inspecting the mummy's back when the arrowhead was discovered, the researchers found a small skin laceration over the scapula. They hypothesized that the arrow entered the left shoulder from the rear, passed through the scapula, and injured a major vessel, resulting in a hematoma.

"The iceman's cause of death by an arrowhead lacerating, among others, a great thoracic artery -- the left subclavian artery -- and leading to a deadly hemorrhagic shock can be now postulated with almost complete certainty, especially when considering environmental (3,210 meters above sea level) and historic (5,300 BP [before present]) settings into account," the researchers concluded.