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Biomedical subjects

S K Koskinen

Publications and source records attributed to S K Koskinen.

At least 19 recordsLinked to original sources
PubMed2005

Magnetic resonance imaging of microneurovascular free muscle flaps in facial reanimation.

The purpose of this study was to describe the survival and volume of microneurovascular muscle flaps at different times after two-stage facial reanimation procedure by using magnetic resonance imaging (MRI) and to compare the functional outcome with MRI findings. Fifteen patients with a mean age of 36 years (range 7-63 years) operated on between 1988 and 1999 were available for this study. The muscles used for functional reconstruction were the latissimus dorsi (eight patients), gracilis (six patients) and serratus anterior (one patient). Hospital charts were reviewed and the clinical outcome of facial reanimation was graded on a scale from 1 to 6 according to House. The mean postoperative follow-up time was 7 years (range 3-14 years). Clinical grading and 1.5 T unit MRI of patients were performed concomitantly. The MR images were evaluated semi-quantitatively so that the muscle structure of the free flaps was graded on a scale from 1 to 4. The free flap area of each slice was defined and the volume of the free flap was calculated. Data were analysed statistically. The long-term functional outcome of the facial reanimation was regarded as good in 10 patients, which means they had only mild or moderate dysfunction of facial movements. In MR images, six free flaps displayed normal muscle structure, another six had a fatty appearance and two displayed severe muscle atrophy; in one patient the muscle tissue could not be identified. The volume of the free flap clearly declined in the course of the follow-up. A correlation was found between good functional outcome and normal muscle structure of the free flap in MRI, p = 0.020. The longer the follow-up time after muscle transplantation the poorer the functional result. A similar correlation was found between abnormal muscle structure in MRI and a long follow-up time. Magnetic resonance imaging can be used to assess the muscle structure of free microneurovascular flaps. Normal findings in MRI seem to correlate with a good clinical outcome in facial reanimation. A good functional result correlates with a shorter follow-up time and normal muscle structure in MRI.

Adolescent↗
PubMed2005

Acute knee trauma: analysis of multidetector computed tomography findings and comparison with conventional radiography.

PURPOSE: To evaluate the multidetector computed tomography (MDCT) findings of acute knee trauma and to compare radiography with MDCT in patients referred to a level 1 trauma center. MATERIAL AND METHODS: During a 5-year period, a total of 415 MDCT examinations were performed on 409 patients with acute knee trauma to reveal complex fracture anatomy or rule out a fracture. MDCT and primary radiographs were re-evaluated with respect to fracture location and trauma mechanism. Tibial plateau fractures were further analyzed depending on anatomical location: anterior-medial, anterior-lateral, posterior-lateral, and posterior-medial regions. Maximal depression of the tibial articular surface was measured. Findings on the primary knee radiographs were compared with MDCT findings. RESULTS: Of the 409 patients, 356 (87%) had a knee fracture. A total of 451 fractures were found in all anatomic regions: distal femur (n=49), proximal tibia (n=307), patella (n=23), and proximal fibula (n=72). Primary radiographs were available in 316 (76%) cases. Of these, 225 (71%) had MDCT in order to reveal the fracture anatomy better, and 91 (29%) had a subsequent MDCT after negative plain radiographs. Overall sensitivity of radiography was 83%, while negative predictive value was 49%. On radiography, tibial plateau articular depression was underestimated in all regions except when the fracture consisted of the whole half of the anterior or posterior plateau. The three main injury mechanisms were traffic accident, a simple fall, and sport. In 49 cases (15%), primary radiographs were suboptimal due to positioning. CONCLUSION: In severely injured patients, diagnostically sufficient radiographs are difficult to obtain, and therefore a negative radiograph is not reliable in ruling out a fracture. In these patients, MDCT is a fast and accurate examination and is also recommended in patients with tibial plateau fractures or complex knee injuries in order to evaluate the fracture adequately.

Adolescent↗
PubMed2005

Evaluation of flexion/extension of the upper cervical spine in patients with rheumatoid arthritis: an MRI study with a dedicated positioning device compared to conventional radiographs.

PURPOSE: Using flexion/extension magnetic resonance imaging (MRI) with a dedicated positioning device, our purpose was to analyze pathologic cranio-vertebral joint anatomy and motion in patients with rheumatoid arthritis in comparison to normal patients, and to compare flexion/extension MRI with conventional radiographs (CRs) in patients with rheumatoid arthritis. MATERIAL AND METHODS: The 31 patients with rheumatoid arthritis and 20 healthy subjects included in the study were imaged in an open MRI scanner during flexion/extension. A dedicated positioning device was used. Additionally, we compared flexion/extension MRI with CRs in patients with rheumatoid arthritis. In MRI, the orientation and segmental motion of C0, C1, and C2 were assessed and structure of the dens and amount of pannus tissue were observed. Configuration of the cerebrospinal fluid space and the cord was evaluated in each position. In both MRI and CRs, anterior atlanto-axial subluxation and vertical dislocation were assessed and sagittal diameter of the dural sac was measured. RESULTS: In the neutral position, C1 of the patients was oriented in a more flexed position in relation to both C0 and C2 compared to that in healthy subjects. The patients had more extension in the upper cervical spine than did healthy subjects. In flexion, atlantoaxial subluxation was greater in CRs than in MRI. In MRI, the amount of vertical dislocation did not depend on position. In the patients, there was considerably more cord impingement in flexion than in other positions. CONCLUSION: Evaluation of the rheumatoid cervical spine is optimized using MR images in the neutral, flexed, and extended positions. Measurements and relationships between structures should be compared in all positions. CRs with flexion-extension views are recommended as the first imaging method.

Adult↗
PubMed2005

Multidetector computed tomography in acute joint fractures.

Conventional radiography plays an essential diagnostic role in the primary evaluation of acute joint trauma. In complex fractures, however, computed tomography (CT) is an imaging modality often used second to radiography. As a result of technical breakthroughs in the field, multidetector CT (MDCT) allows faster imaging and better temporal, spatial, and contrast resolution compared with conventional single-slice spiral CT. MDCT with multiplanar reformation is helpful in disclosing fracture patterns, particularly in complex joint fractures, where they reveal occult fractures and show the exact number of fracture components and their degree of displacement.

Arthrography↗
PubMed2004

Multidetector computed tomography of cervical spine fractures in ankylosing spondylitis.

PURPOSE: To analyze multidetector computed tomography (MDCT) cervical spine findings in trauma patients with advanced ankylosing spondylitis (AS). MATERIAL AND METHODS: Using PACS, 2282 cervical spine MDCT examinations requested by emergency room physicians were found during a period of 3 years. Of these patients, 18 (16 M, aged 41-87, mean 57 years) had advanced AS. Primary imaging included radiography in 12 and MRI in 11 patients. RESULTS: MDCT detected one facet joint subluxation and 31 fractures in 17 patients: 14 transverse fractures, 8 spinous process fractures, 2 Jefferson's fractures, 1 type I and 2 type II odontoid process fractures, and 1 each: atlanto-occipital joint fracture and C2 laminar fracture plus isolated transverse process and facet joint fractures. Radiographs detected 48% and MRI 60% of the fractures. MRI detected all transverse and odontoid fractures, demonstrating spinal cord abnormalities in 72%. CONCLUSION: MDCT is superior to plain radiographs or MRI, showing significantly more injuries and yielding more information on fracture morphology. MRI is valuable, however, in evaluating the spinal cord and soft-tissue injuries. Fractures in advanced AS often show an abnormal orientation and are frequently associated with spinal cord injuries. In these patients, for any suspected cervical spine injuries, MDCT is therefore the imaging modality of choice.

Adult↗
PubMed2004

Multidetector computed tomography diagnosis of adult elbow fractures.

PURPOSE: To assess acute phase multidetector computed tomography (MDCT) findings in elbow traumas. MATERIAL AND METHODS: Fifty-six patients (32 M, 24 F, age 16 to 88 years, mean 44 years) underwent MDCT of the elbow due to an acute trauma during a time period of 34 months. RESULTS: A total of 65 fractures and 3 main fracture types were established: 16 (25%) ulnar coronoid process fractures, 13 (20%) radial head fractures, and 12 (18%) humeral supracondylar fractures. Three main injury mechanisms were falling (38 (68%) patients), falling from high places (6 (11%) patients), and traffic accidents (5 (9%) patients). In 6 (11%) patients, MDCT revealed 13 occult fractures in the elbow joint compared to primary radiography. In four (7%) patients a displaced fracture fragment was detected in primary radiography, but the origin of the fragment was unclear. In all four cases, MDCT revealed the origin of the fragment. CONCLUSION: Radiography remains the primary imaging modality in elbow trauma, but in complex fracture patterns, where the extent of the fractures and the position or origin of dislocated fragments is not clear by radiography, the MDCT is a recommended complementary examination.

Adolescent↗
PubMed2004

Factors associated with nonunion in conservatively-treated type-II fractures of the odontoid process.

In type-II fractures of the odontoid process, the treatment is either conservative in a halo vest or primary surgical stabilisation. Since nonunion, requiring prolonged immobilisation or late surgery, is common in patients treated in a halo vest, the identification of those in whom this treatment is likely to fail is important. We reviewed the data of 69 patients with acute type-II fractures of the odontoid process treated in a halo vest. The mean follow-up was 12 months. Conservative treatment was successful, resulting in bony union in 32 (46%) patients. Anterior dislocation, gender and age were unrelated to nonunion. However, nonunion did correlate with a fracture gap (> 1 mm), posterior displacement (> 5 mm), delayed start of treatment (> 4 days) and posterior redisplacement (> 2 mm). We conclude that patients presenting with these risk factors are unlikely to achieve bony union by treatment in a halo vest. They deserve careful attention during the follow-up period and should also be considered as candidates for primary surgical stabilisation.

Adolescent↗
PubMed2000

Interventional and intraoperative magnetic resonance imaging.

The goal of the Image Guided Therapy Program, as the name implies, is to develop the use of imaging to guide minimally invasive therapy. The program combines interventional and intraoperative magnetic resonance imaging (MRI) with high-performance computing and novel therapeutic devices. In clinical practice the multidisciplinary program provides for the investigation of a wide range of interventional and surgical procedures. The Signa SP 0.5 T superconducting MRI system (GE Medical Systems, Milwaukee, WI) has a 56-cm-wide vertical gap, allowing access to the patient and permitting the execution of interactive MRI-guided procedures. This system is integrated with an optical tracking system and utilizes flexible surface coils and MRI-compatible displays to facilitate procedures. Images are obtained with routine pulse sequences. Nearly real-time imaging, with fast gradient-recalled echo sequences, may be acquired at a rate of one image every 1.5 s with interactive image plane selection. Since 1994, more than 800 of these procedures, including various percutaneous procedures and open surgeries, have been successfully performed at Brigham and Women's Hospital (Boston, MA).

Biomedical Engineering↗
PubMed1999

Kinematic magnetic resonance imaging of the upper cervical spine using a novel positioning device.

STUDY DESIGN: The development of a novel positioning device for magnetic resonance imaging of the upper cervical spine and an evaluation of motion patterns of the craniovertebral junction in asymptomatic volunteers as a part of the whole cervical spine motion. OBJECTIVES: To design and construct a positioning device that enables magnetic resonance imaging of the cervical spine in rotation, lateral bending, flexion, and extension in a horizontally open magnetic resonance scanner, and to define reference values for movements of the occiput (C0), the atlas (C1), and the axis (C2) in asymptomatic volunteers. SUMMARY OF BACKGROUND DATA: In previously used devices, the direction of motion is limited usually to flexion-extension, or the position of the head and neck are adjusted without a positioning device using semihard wedges or pillows. METHODS: Magnetic resonance imaging of the upper cervical spine in 20 asymptomatic individuals (10 men and 10 women) was performed in a horizontally open 0.23-T magnetic resonance imager in progressive steps during rotation, lateral bending, and flexion-extension using axial, coronal, and sagittal imaging planes, respectively. The positions of C0, C1, and C2 were measured, and pattern of motions between segments analyzed. Lateral displacement of the atlas during lateral bending and cranial migration distance during flexion-extension were assessed. RESULTS: The nonferromagnetic positioning device was designed and constructed. The motion patterns of the craniovertebral junction during rotation did not differ between the men and women, but in lateral bending there was a small difference between genders at C1-C2. In men, the position of C1 during flexion-extension was consistently more extended in relation to C0 and C2 than in women. CONCLUSIONS: The new positioning device allows magnetic resonance imaging of the upper cervical spine during flexion, extension, rotation, and lateral bending. To assess the relationship between C0-C1 and C1-C2 in flexion and extension, separate reference values for men and women are recommended.

Adolescent↗
PubMed1999

Medial tibial pain: a dynamic contrast-enhanced MRI study.

The purpose of this study was to compare the sensitivity of different magnetic resonance imaging (MRI) sequences to depict periosteal edema in patients with medial tibial pain. Additionally, we evaluated the ability of dynamic contrast-enhanced imaging (DCES) to depict possible temporal alterations in muscular perfusion within compartments of the leg. Fifteen patients with medial tibial pain were examined with MRI. T1-, T2-weighted, proton density axial images and dynamic and static phase post-contrast images were compared in ability to depict periosteal edema. STIR was used in seven cases to depict bone marrow edema. Images were analyzed to detect signs of compartment edema. Region-of-interest measurements in compartments were performed during DCES and compared with controls. In detecting periosteal edema, post-contrast T1-weighted images were better than spin echo T2-weighted and proton density images or STIR images, but STIR depicted the bone marrow edema best. DCES best demonstrated the gradually enhancing periostitis. Four subjects with severe periosteal edema had visually detectable pathologic enhancement during DCES in the deep posterior compartment of the leg. Percentage enhancement in the deep posterior compartment of the leg was greater in patients than in controls. The fast enhancement phase in the deep posterior compartment began slightly slower in patients than in controls, but it continued longer. We believe that periosteal edema in bone stress reaction can cause impairment of venous flow in the deep posterior compartment. MRI can depict both these conditions. In patients with medial tibial pain, MR imaging protocol should include axial STIR images (to depict bone pathology) with T1-weighted axial pre and post-contrast images, and dynamic contrast enhanced imaging to show periosteal edema and abnormal contrast enhancement within a compartment.

Adolescent↗
PubMed1999

T1rho dispersion of rat tissues in vitro.

The purpose of this study was to demonstrate T1rho dispersion in different rat tissues (liver, brain, spleen, kidney, heart, and skeletal muscle), and to compare the 1/T1rho data to previous 1/T1 data and magnetization transfer of rat tissues at low (0.1 T) B0 field. The 1/T1rho dispersion showed a fairly similar pattern in all tissues. The highest 1/T1rho relaxation rates were seen in liver and muscle followed by heart, whereas the values for spleen, kidney, and brain were quite similar. Compared to 1/T2 relaxation rate, the greatest difference was seen in liver and muscle. The rank order 1/T1rho value at each locking field B1 was the same as the transfer rate of magnetization from the water to the macromolecular pool (Rwm) for liver, muscle, heart, and brain. The potential value T1rho imaging is to combine high T1 contrast of low field imaging with the high signal to noise ratio of high static field imaging. When the T1rho value for a given tissue is known, the contrast between different tissues can be optimized by adjusting the locking time TL. Further studies are encouraged to fully exploit this. Targets for more detailed research include brain infarct, brain and liver tumors.

Animals↗
PubMed1999

Magnetic resonance imaging-guided focused ultrasound synovectomy.

OBJECTIVE: To investigate the feasibility of magnetic resonance imaging (MRI)-guided high power focused ultrasound (FUS) to perform synovectomy noninvasively. METHODS: Five New Zealand white male rabbit knees with experimentally induced arthritis underwent MRI-guided thermal surgery by high power (60 W/10 s) sonication. Evidence of tissue coagulation was monitored during the procedure and confirmed by gross and microscopic evaluation and MRI. RESULTS: Partial synovectomy was performed in five animals. Necrotized synovial tissue was observed on gross and microscopic evaluation. Visible signal intensity alterations including high signal intensity on T2-weighted (T2W) images and lack of contrast-enhancement on T1-weighted (T1W) post-contrast, post-sonication images were characteristic and reproducible. CONCLUSION: Our results demonstrate the ability of high power sonication to destroy synovial tissue in vivo.

Animals↗
PubMed1999

Associations of isometric and isoinertial trunk muscle strength measurements and lumbar paraspinal muscle cross-sectional areas.

The relationships of dynamic and static trunk muscle strength measurements and muscle geometry are studied. Physiologically, isometric muscle strength is directly related to muscle cross-sectional area. We measured isometric and isoinertial trunk muscle strength of 111 former elite male athletes, aged 45-68, by Isostation B-200. Paraspinal muscle cross-sectional areas were measured from axial magnetic resonance images at the L3-L4 level. Isometric and isoinertial torques were closely related, but angular velocities were not predicted by isometric maximal torque. The area of the psoas muscles correlated with isometric maximal flexion, as well as with isoinertial maximal torque. angular velocity, and power in flexion (r = 0.24-0.27). The area of the extensor group correlated with isometric maximal extension and with isoinertial maximal torque and power in extension (r = 0.24-0.25). We conclude that dynamic and static strength measurements are closely related, with angular velocity giving additional information on muscle function. Paraspinal muscle cross-sectional area is one determinant of isometric and isoinertial trunk muscle strength.

Aged↗
PubMed1998

Glomus tumor of the trachea.

We report a case of a glomus tumor in the trachea which was an incidental finding in a 66-year-old man. The histological picture and immunohistochemical profile were typical for this tumor. The glomus tumor is an exceedingly rare mass lesion in the trachea, but it is useful to keep it among differential diagnostic alternatives when a tracheal tumor is seen on radiographs or endoscopy.

Actins↗
PubMed1998

Incidence and clinical significance of bone bruises after supination injury of the ankle. A double-blind, prospective study.

We used MRI to study a prospective series of 95 patients with inversion injuries of the ankle and no fracture on plain radiographs. We found an incidence of bone bruises of 27%, but these made no difference to the time of return to work, limitation of walking or physical activity, or the clinical outcome scores at three months. We conclude that bone bruises have very little clinical significance after inversion injuries of the ankle.

Absenteeism↗
PubMed1998

Effect of Elmslie-Trillat and Roux-Goldthwait procedures on patellofemoral relationships and symptoms in patients with patellar dislocations.

Seventeen patients (18 knees) with a history of one or more patellar dislocations underwent Elmslie-Trillat (9 knees [group 1]) or Roux-Goldthwait (9 knees [group 2]) patellar realignment surgery. Anterior knee pain was evaluated with a questionnaire, and lateral patellar displacement and tilt were analyzed by magnetic resonance imaging both pre- and postoperatively. Postoperative evaluations were performed after 44 and 50 months (mean) in groups 1 and 2, respectively. The Elmslie-Trillat procedure provided better subjective relief of anterior knee pain and symptoms. One redislocation occurred in each group. Both procedures relieved excessive patellar lateralization, but the effect on patellar tilt was less marked. In patients who underwent the Roux-Goldthwait operation, a less pronounced correction of tilt and lateralization appeared to correlate with more satisfactory subjective results.

Adolescent↗
PubMed1997

Orthopedic and interventional applications at low field MRI with horizontally open configuration. A review.

The recently introduced horizontally open configuration imagers allow imaging of knee, hip or shoulder during whole range of motion, which is not possible in conventional MR imagers. Special joint motion devices can be used to provide accurate and reproducible studies. In cervical spine, functional MR imaging may be useful in evaluating alarligament stability in patients with late sequelae of a whiplash injury, and in patients with rheumatoid arthritis who are clinically suspected of having a cervical myelopathy or superior migration of the odontoid process. In shoulder, full range of motion abduction study may be helpful in assessing the supraspinatus tendon impingement. To evaluate patellofemoral malalignment, quadriceps loading is recommended since associated contracting muscles and related soft tissue structures can be evaluated. The position of the femoral head relative to the acetabulum during different positions can be assessed. Open-configuration scanners provide an access to patients during scanning procedure, and therefore permit interventional procedures to be monitored with MRI. Such interventions include aspiration cytology/biopsy and different drainage procedures.

Arthritis, Rheumatoid↗