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Dynamic MRI color mapping estimates femoral head perfusion preoperatively
3-minute imaging study displays three grades of perfusion, guiding surgeons’ operative choices.
SAN FRANCISCO — Japanese investigators quickly and accurately predicted the amount of femoral head perfusion with displaced and nondisplaced femoral head fractures using dynamic MRI positive enhancement integral color mapping.
Their research demonstrated how useful the new technique is for helping surgeons predict the success of using surgical interventions such as osteosynthesis or primary hemiarthroplasty to treat these fractures. Positive enhancement integral color mapping (PEICM) produced validated results, according to investigators.
In our study, “PEICM positively demonstrated the degree of femoral head perfusion with certainty,” Takahiro Kubo, MD, PhD, said.
PEICM study
During the American Academy of Orthopaedic Surgeons 75th Annual Meeting, Kubo presented results using PEICM in 41 patients with femoral neck fractures (13 men, 28 women; average age 77 years). The study’s findings suggested PEICM could potentially become a new tool for classifying femoral neck fractures.
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Investigators initially classified the femoral neck fractures studied using Garden’s classification where Stages I and II consisted of undisplaced neck fractures and Stages III and IV were displaced, based on radiographs.
They identified five fractures as Stage I, eight as Stage II, 22 as Stage III and six as Stage IV.
All patients underwent PEICM with a 1.5 Tesla MRI machine using coronal fast spoiled gradient echo imaging (SPGR) sequences with gadopentetate dimeglumine (Gd-DTPA) as the contrast agent. Investigators repeated SPGR sequences every 16 seconds for a total dynamic examination time of about 224 seconds.
Types A, B or C
The PEICM technique produced three head-perfusion types, A, B or C, displayed via color mapping where red represented a high degree of perfusion and black represented the absence of perfusion.
For Type A neck fractures, femoral head perfusion displayed in the same color as the unaffected contralateral femoral head. Type B displayed darker than the unaffected side, indicating that femoral head perfusion is less compared with the unaffected side. “For Type C the color is black. This means no flow of blood to the femoral head,” Kubo explained.
The assessment resulted in 11 Type A fractures, 20 Type B fractures, and 10 fractures that were Type C. “Interestingly, 18 out of 28 patients had 64.6% of the displaced fractures considered Type A and B. These results indicated that femoral head perfusion was often maintained even in displaced femoral neck fractures,” he said.
Results were good following osteosynthesis with three cannulated screws in 26 of 31 patients based on PEICM findings (83.9%). Two of the other five patients who underwent osteosynthesis had late femoral head collapse. Three patients had nonunions.
“In this study most of the Type A or B fractures were treated successfully by osteosynthesis even though they were displaced,” Kubo noted.
Bruce Ziran, MD, who co-moderated the session where the research was presented, said it “has the potential to change how we classify femoral neck fractures.”
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| Japanese investigators devised and validated use of a positive enhancement integral color mapping (PEICM) system to grade femoral head perfusion after neck fractures in 41 patients. PEICM uses dynamic color MRI to classify the fractures as type (left to right) A, B and C according to how perfusion is affected. In each of these cases the left femoral neck is fractured. The color MRI is the same for the fractured side and the right unfractured side with a type A neck fracture. With type B fractures the MRI appears much darker on the left than the uninjured side. For type C fractures, it produces a black image indicating severely affected head perfusion. Images: Kubo T | ||
For more information:
- Takahiro Kubo, MD, PhD, can be reached at the Dept. of Orthopaedic Surgery, Mitoyo General Hospital, 708 Himehama, Toyohama, Kanonji, Kagawa, 769-1695, Japan; +81-875-52-3366; e-mail: takahiro707@msn.com. He has no direct financial interest in any products or companies mentioned in this article.
- Bruce Ziran, MD, can be reached at St. Elizabeth Health Center, 1044 Belmont Ave., Youngstown, OH 44501, U.S.A.; +1-330-480-2986; e-mail: Bruce_Ziran@hmis.org. He received research support from Medtronic, received miscellaneous support and is a consultant to Stryker, received miscellaneous support from AO, and is a consultant to Synthes.
Reference:
- Kubo T, Nagamachi A, Suganuma K, Endo T. Dynamic MRI positive enhancement integral color mapping in femoral neck fractures. #384. Presented at the American Academy of Orthopaedic Surgeons 75th Annual Meeting. March 5-9, 2008. San Francisco.