Fast Acquisition Magnetic Resonance Research Articles

Effect of Impairment-Based Rehabilitation on Lower Leg Muscle Volumes and Strength in Patients With Chronic Ankle Instability: A Preliminary Study.

Context: Patients with chronic ankle instability (CAI) have demonstrated atrophy of foot and ankle musculature and deficits in ankle strength. The effect of rehabilitation on muscle morphology and ankle strength has not previously been investigated in patients with CAI. Objective: Our objective was to analyze the effect of impairment-based rehabilitation on intrinsic and extrinsic foot and ankle muscle volumes and strength in patients with CAI. Design: Controlled laboratory study. Setting: Laboratory. Patients: Five young adults with CAI. Intervention: Twelve sessions of supervised impairment-based rehabilitation that included range of motion, strength, balance, and functional exercises. Main Outcome Measures: Measures of extrinsic and intrinsic foot muscle volume and ankle strength measured before and after 4 weeks of supervised rehabilitation. Novel fast-acquisition magnetic resonance imaging was used to scan from above the femoral condyles through the entire foot. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5mm) to calculate muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a hand-held dynamometer. Results: Rehabilitation resulted in hypertrophy of all extrinsic foot muscles except for the flexor hallucis longus and peroneals. Large improvements were seen in inversion, eversion, and plantar flexion strength following rehabilitation. Effect sizes for significant differences following rehabilitation were all large and ranged from 1.54 to 3.35. No significant differences were identified for intrinsic foot muscle volumes. Conclusion: Preliminary results suggest that impairment-based rehabilitation for CAI can induce hypertrophy of extrinsic foot and ankle musculature with corresponding increases in ankle strength.

Diminished Foot and Ankle Muscle Volumes in Young Adults With Chronic Ankle Instability.

Background:Patients with chronic ankle instability (CAI) have demonstrated altered neuromuscular function and decreased muscle strength when compared with healthy counterparts without a history of ankle sprain. Up to this point, muscle volumes have not been analyzed in patients with CAI to determine whether deficits in muscle size are present following recurrent sprain.Purpose:To analyze intrinsic and extrinsic foot and ankle muscle volumes and 4-way ankle strength in young adults with and without CAI.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Five patients with CAI (mean age, 23.0 ± 4 years; 1 male, 4 females) and 5 healthy controls (mean age, 23.8 ± 4.5 years; 1 male, 4 females) volunteered for this study. Novel fast-acquisition magnetic resonance imaging (MRI) was used to scan from above the femoral condyles through the foot and ankle. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate the muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a handheld dynamometer. Patients with CAI were compared with healthy controls on all measures of muscle volume and strength. Extrinsic muscle volumes of patients with CAI were also compared with a normative database of healthy controls (n = 24) by calculating z scores for each muscle individually for each CAI subject.Results:The CAI group had smaller total shank, superficial posterior compartment, soleus, adductor hallucis obliqus, and flexor hallucis brevis muscle volumes compared with healthy controls as indicated by group means and associated 90% CIs that did not overlap. Cohen d effect sizes for the significant group differences were all large and ranged from 1.46 to 3.52, with 90% CIs that did not cross zero. The CAI group had lower eversion, dorsiflexion, and 4-way composite ankle strength, all with group means and associated 90% CIs that did not overlap. No other significant differences were identified.Conclusion:Patients with CAI demonstrate atrophy of intrinsic and extrinsic foot and ankle musculature accompanied by lower ankle strength.Clinical Relevance:Clinicians should be aware of the muscle atrophy and strength deficits when prescribing rehabilitation for patients with lateral ankle sprain or CAI.

A study of prenatal ultrasound and postnatal magnetic imaging in the diagnosis of central nervous system abnormalities.

Accurate prenatal diagnosis of central nervous system (CNS) abnormalities is essential in counselling parents, as they are the most common developmental abnormalities causing considerable mortality. Currently, the standard in prenatal imaging is ultrasound scanning (USS). The introduction of fast acquisition magnetic resonance imaging (MRI) has lead to increased diagnostic confidence and information available for parents. Frequently USS initially identifies CNS abnormalities as ventriculomegaly alone. However, it is known that ventriculomegaly is commonly associated with other CNS pathology, which may adversely affect the prognosis. As MRI has superior soft tissue resolution and can be used at any time postnatally, it is expected to identify disorders of myelination that may result from prenatal ventriculomegaly. This study will evaluate the role of MRI as a postnatal imaging tool in patients that had a prenatal USS diagnosis of isolated ventriculomegaly. This was a retrospective review of patient notes and scan reports. The postnatal MRI study group consisted of 9 patients that had been diagnosed initially with prenatal isolated ventriculomegaly on USS, and followed up with postnatal MRI (cases of spina bifida and Dandy-Walker malformations were excluded). Findings from the scan reports were recorded and analysed. Both MRI and prenatal USS gave the same information in 55.6 % of the patients. In the remaining 44.4 %, MRI added to the information provided by the prenatal USS. An interesting finding was that MRI missed a small fluid-filled cyst and an arachnoid cyst in 2 cases. 55.6 % of patients went on to develop other CNS abnormalities prenatally, whereas 33.3 % showed prenatal regression of VM with no other pathology. 11.1 % showed postnatal persistence of isolated VM. As USS has the advantage of being cheap and easy to perform, it will remain as the primary imaging tool in obstetric care. MRI can provide significant additional information that can affect parent counselling, prenatal intervention, and postnatal management. Postnatally, MRI can give some idea of prognosis by evaluating myelination patterns, which is not possible with USS.

Feasibility of the fetal anatomic and maternal pelvic survey by magnetic resonance imaging at term

Objective This study was undertaken to determine which nonbiometric components of the American College of Obstetricians and Gynecologists recommended ultrasound fetal anatomic and maternal pelvic survey can be evaluated by fast acquisition magnetic resonance (MR) imaging in the term fetus. Study design Nonbiometric components of the fetal survey were retrospectively evaluated by fast acquisition MR images. Thirteen components were assessed, including fetal number, presentation, placental location, qualitative assessment of amniotic fluid, and the maternal pelvis (n = 5). The fetal anatomy included bilateral cerebral ventricles, spine, bilateral kidneys, stomach, bladder, cord insertion, sex, and four-chamber view of the heart (n = 8). Studies were performed before delivery and neonatal outcomes were reviewed. Results All 50 neonates were normal at follow-up. A total of 94% (702 of 750) of the components were assessed by MR imaging. Conclusion Fetal MR imaging can assess 94% of the American College of Obstetricians and Gynecologists recommended ultrasound fetal and pelvic anatomic survey. If the heart is excluded, this increases to 99%.

Single uterine axial fast acquisition magnetic resonance fetal survey: is it feasible?

Objectives: To determine which non-biometric components of the ultrasound fetal survey can routinely be seen on a single fast acquisition magnetic resonance (MR) sequence aligned axial to the maternal uterus. Study design: The non-biometric components of the routine fetal ultrasound examination were applied retrospectively to the initial MR single-shot fast spin-echo acquisition aligned axial to the maternal uterus in the normal fetus to determine whether these parameters could be routinely evaluated. Nineteen women with anatomically normal fetuses had a total of 31 MR studies performed for fetal or maternal indications, either as part of an indicated examination or as part of a study protocol approved by the institutional review board. The images in these 31 MR studies were reviewed by two independent examiners who were blinded to the other's assessment; concordance was necessary for a component to be adequately assessed. The Wilcoxon rank sum test was used to determine the effect of gestational age and fetal lie on the ability to assess non-biometric parameters. Results: Assessment was possible in 85% of the non-biometric parameters. Cord insertion, external genitalia and the four-chamber view of the heart were most problematic. In only two cases was the four-chamber view of the heart identified. Longitudinal lie allowed significantly more parameters (82%) to be evaluated than transverse lie (45%) (p < 0.003). No difference based on gestational age was found. Conclusion: A single fast acquisition axial MR sequence can evaluate 85% of the non-biometric components of the fetal ultrasound survey. Fetal lie is an important confounder in the ability to resolve fetal anatomy with a single MR axial uterine acquisition.

Single uterine axial fast acquisition magnetic resonance fetal survey: is it feasible?

Objectives: To determine which non-biometric components of the ultrasound fetal survey can routinely be seen on a single fast acquisition magnetic resonance (MR) sequence aligned axial to the maternaluterus.Study design: The non-biometric components of the routine fetal ultrasound examination were applied retrospectively to the initial MR single-shot fast spin-echo acquisition aligned axialto the maternal uterus in the normal fetus to determine whether these parameters could be routinely evaluated. Nineteen women with anatomically normal fetuses had a total of 31 MR studies performed forfetal or maternal indications, either as part of an indicated examination or as part of a study protocol approved by the institutional review board. The images in these 31 MR studies were reviewed by twoindependent examiners who were blinded to the other's assessment; concordance was necessary for a component to be adequately assessed. The Wilcoxon rank sum test was used to determine the effect of gestationalage and fetal lie on the ability to assess non-biometric parameters.Results: Assessment was possible in 85% of the non-biometric parameters. Cord insertion, external genitalia and the four-chamberview of the heart were most problematic. In only two cases was the four-chamber view of the heart identified. Longitudinal lie allowed significantly more parameters (82%) to be evaluated than transverselie (45%) (p < 0.003). No difference based on gestational age was found.Conclusion: A single fast acquisition axial MR sequence can evaluate 85% of the non-biometric components ofthe fetal ultrasound survey. Fetal lie is an important confounder in the ability to resolve fetal anatomy with a single MR axial uterine acquisition.