Bone marrow edema: pathophysiology, differential diagnosis, and imaging.

Bone marrow edema (BME) has been a topic of increasing interest in the literature in recent years. BME is associated with numerous pathologies and is becoming recognized not only as a considerable pain generator, but also as an entity which is, in some cases, significantly linked to the worsening of patient prognosis. To date, no thorough imaging review of BME has been published. An electronic literature search was conducted through PubMed with a time parameter of January 1975 through December 2007. The primary search parameter was "bone marrow edema." Over 800 papers were listed as written in English and involving humans. Other refining parameters included "AND syndrome," "AND transient," "AND arthritis," "AND infection," "AND tumor," "AND neoplasm," "AND iatrogenic," "AND radiation therapy," and "AND inflammation." More current articles were favored over dated articles on the same topic. A total of 106 journal articles were collected concerning BME and multiple pathologic processes. The data contained therein was compiled and organized into a comprehensive format. BME can be caused by, and found concurrent with, a broad spectrum of pathologies which exhibit a variety of imaging findings. BME is also associated with the deterioration of certain pathologies. This presentation is a comprehensive discussion of different pathological conditions inducing or associated with BME. Differential diagnosis through appropriate imaging is vital to case management and could contribute to the prevention or decreased progression of certain pathologies. Continued investigation into the imaging of BME and its associated diseases, as well as the effect of BME on prognosis, is warranted.

Quantitative cerebral MR in rheumatoid arthritis.

PURPOSE: To determine the presence of hyperintense white matter lesions and atrophy reflecting cerebral vasculitis in rheumatoid arthritis. METHODS: Thirty-three patients with rheumatoid arthritis and 48 control subjects were examined with MR. Mean age was 45.1 years (range, 26 to 55 years) for the patients and 42.2 years (range, 25 to 55 years) in the control group. To determine atrophy we measured the area of corpus callosum, the cerebrum, and the cerebellum on midline sagittal sections. On transverse images, the ventricle-to-brain ratio, the bifrontal ratio, and the bicaudate ratio were selected as atrophy parameters. Area and signal intensity were measured for the biggest and the smallest lesions in both groups. RESULTS: Nine patients (27%) had hyperintense lesions compared with 15 (31%) of the control subjects. Mean numbers of hyperintense lesions were 1.3 in patients and 2.1 in control subjects. Mean area of the largest lesion in each patient was 27.4 mm2 for the patients and 29.8 mm2 in the control group. In patients with long disease duration (> 15 years) the mean ventricle-to-brain ratio was 0.09 compared with 0.08 in the control subjects. The midsagittal area of the cerebellum was 1349.8 mm2 in the patients with long disease duration and 1573.3 mm2 in the control group. No difference in number of hyperintense white matter lesions was detected between patients with long disease duration and the control subjects. Comparing the total group of patients with the control subjects, no significant differences in atrophy parameters or hyperintense white matter lesions were found. Also, there were no significant differences in relative signal intensity of the hyperintense lesions and corpus callosum between the two groups. We were not able to detect differences between treated versus untreated patients. CONCLUSION: This study indicates a tendency of more cerebral and cerebellar atrophy in patients with severe rheumatoid arthritis. The number and size of the white matter lesions were not significantly different in the two groups and do not support a higher frequency of even clinically silent infarcts caused by vasculitis in the patients with rheumatoid arthritis compared with control subjects.

Necrotizing fasciitis: unreliable MRI findings in the preoperative diagnosis.

The authors present two cases of necrotizing fasciitis (NF), one case of dermatomyositis and one case of posttraumatic muscle injury, which have similar magnetic resonance imaging findings in terms of skin, subcutaneous fat, superficial and deep fasciae and muscle involvement. These cases highlight the need for cautious interpretation of magnetic resonance imaging (MRI) findings, for they are nonspecific and the preoperative decision should be based mostly on the evolution of the clinical status.

Quantitative magnetic resonance imaging and the electrophysiology of the carpal tunnel region in floor cleaners.

OBJECTIVES: The purpose of this study was to evaluate possible structural changes of the wrist and subclinical damage in the median nerves of healthy floor cleaners. METHODS: Twenty-four cleaners and 19 referents (noncleaners), all women, underwent bilateral magnetic resonance (MR) wrist examination and nerve conduction studies. They were all randomly selected from an occupational health service. From MR images the volumes of the wrist, carpal tunnel, and thenar and hypothenar muscles were calculated, as well as the signal intensity of the median nerve, bilaterally. RESULTS: No significant difference in the volume of the carpal tunnel was found in the two groups. The relative signal intensity of the median nerve was 0.55 for the cleaners and 0.48 for the referents (P = 0.05). The mean nerve conduction velocity values were 55.2 m.s-1 for the right median nerve of the cleaners and 57.4 m.s-1 for the right median nerve of the referents (P = 0.03). The median nerve of the cleaners had a mean sensory amplitude of 128.2 microV compared with 162.8 microV for the referents (P = 0.01). There was a tendency towards a longer distal latency of the median nerve in the cleaner group. CONCLUSIONS: This study revealed subclinical intrinsic damage to the median nerve, as demonstrated by MR, and poorer electrophysiological nerve function among workers at high risk (cleaners) compared with workers at lower risk (noncleaners).

Bilateral fast MR imaging of the rheumatoid wrist.

To evaluate the structural changes in the carpal tunnel and possible intrinsic median nerve damages in RA patients, quantitative bilateral magnetic resonance imaging (MRI) of the wrists was performed by means of a fast imaging sequence. Thirty-three women with RA and 42 controls were examined. The length of the carpal tunnel, the carpal tunnel volume/wrist volume (CTV/WV) ratio and the signal intensity of the nerve were calculated in both groups, bilaterally. The CTV/WV ratio was 0.12 in the patients and 0.11 in the control group (p = 0.007). A negative association was found between disease duration and carpal tunnel volume/wrist volume ratio (p = 0.049). Mean distal latency in the right motor median nerve was 3.0 +/- 0.4 msec (patients) and 3.4 +/- 0.6 msec (controls) (p = 0.002). Mean values in the right sensory branch were 1.2 +/- 0.1 msec (patients) and 1.4 +/- 0.3 (controls) (p = 0.01). The lack of association between the size of the carpal canal and neurophysiological parameters found in this study may suggest a possible protection of the median nerve by the increased canal size in patients with RA.

The rheumatoid wrist: bilateral MR analysis of the distribution of rheumatoid lesions in axial plan in a female population.

In this case-control study, we analyzed 146 wrists: a) to search for the distribution pattern of the rheumatoid lesions and, b) to correlate the distribution pattern of these lesions with the clinical parameters. Thirty-one patients with rheumatoid arthritis (RA) and 42 controls-all women-were examined by means of a bilateral MR fast field echo (FFE) sequence, in axial plan. The wrist was divided into three regions: metacarpal (level I), carpal (level II) and radioulnar (level III). Erosions were present in thirty (97%) patients and in six (14%) controls. They were asymmetrically distributed at all levels, mainly at level II. Marrow infiltration and bone destruction were seen in 35% of the patients in an asymmetrical pattern at level I and II, respectively. These lesions were absent in the control group. Subchondral cysts were asymmetrically present in both groups-in 48% of the patients at levels II and III, and in 11% of the controls at level II. In the patient group, this asymmetrical pattern of the lesions correlated with the disease duration at levels I and II (p = 0.011 and p = 0.013, respectively). Most lesions were found at the radial force-bearing column of the wrist, more in the right side. Synovial hypertrophy and hyperintense median nerve were evident in 96% and 70% of the patients, respectively. We concluded that contrary to common belief rheumatoid damages to the carpal bones become rather asymmetrical as the disease progresses. The line of force along the radial side of the wrist possibly influences the distribution pattern of the rheumatoid lesions.

Bilateral fast magnetic resonance imaging of the operated carpal tunnel.

Our aim was to quantify the structural changes of the carpal tunnel including area and volume after surgical release. We studied 28 patients who underwent 31 operations for carpal tunnel syndrome (CTS), mean age 54.7 years (range 32-78). All had abnormal nerve conduction studies. Magnetic resonance imaging (MRI) of both wrists was done before and after operation using two fast imaging sequences, turbo spin echo (TSE) and fast field echo (FFE). The same surface coils and parameters were used in both instances. With a computerised analyser we calculated the volume of the whole tunnel from inlet to outlet before and after operation and the wrist volume:carpal tunnel volume ratio. The intensity of the magnetic resonance signal emitted by the median nerve was assessed in all wrists before and after operation. The mean (SD) volume of the tunnel in 31 wrists with CTS was 11511.7 (2857) mm3 before and 13803.4 (3034.9) mm3 after operation (p = 0.0001). The mean (SD) relative signal intensity of the median nerve was 1.7 (1.8) preoperatively and 1.3 (1.1) postoperatively (p = 0.19). Other postoperative changes included persistent nerve enlargement (n = 21), misalignment of the tendons (n = 20), fibrous tissue deposits (n = 20), fat tissue deposits (n = 21), and muscle oedema (n = 6). The modifications of the carpal canal as a consequence of open surgical release (including increased volume and displacement of the flexor tendons) argue for the use of an endoscopic procedure in the treatment of CTS.

[Carpal tunnel syndrome]. / Karpaltunnelsyndrom.

BACKGROUND: Carpal tunnel syndrome is the most common mononeuropathy. Typical symptoms include pain or discomfort in the hand, paresthesia, weakness and altered temperature or dryness of the skin along with neurophysiological findings. The presence of these symptoms in the area of the median nerve distribution supports the diagnosis. MATERIAL AND METHODS: This review article is based on current knowledge about carpal tunnel syndrome as obtained from the Medline and the Cochrane database systems. RESULTS: The prevalence of carpal tunnel syndrome in the population is around 3%. A higher incidence is reported in women and in manual workers in general. The higher incidence in women may be less evident than previously expected. The size of the carpal canal do not predict the disease, but narrowing of the canal in its distal third has been reported in both patients and non-symptomatic controls. INTERPRETATION: Differences in job exposure between men and women may explain the increased incidence in women. Although the relationship between symptom production and structural changes in the carpal tunnel affecting the median nerve is still debated, narrowing of the canal in its distal third may predict the syndrome.

Magnetic resonance imaging of the wrist: occult osseous lesions.

This article illustrates the magnetic resonance imaging (MRI) features of occult osseous lesions in three different patients. All three patients suffered from a history of wrist trauma, but had negative plain film radiographs. The three types of occult lesions (bone bruise, microfracture and chronic osseous damage) are described, and their MRI characteristics are demonstrated by proton density and T2 weighted images. MRI proved to be the diagnostic modality of choice for the detection of posttraumatic intrinsic marrow changes.

Magnetic resonance spin echo and fast field echo imaging of aneurysmal bone cyst: comparison with X-ray and computed tomography.

OBJECTIVE: To discuss the case of an 8-yr-old boy with an aneurysmal bone cyst of the right proximal humerus, including the features imaged on plain film radiography, computed tomography (CT), magnetic resonance imaging (MRI), including spin echo and fast field echo imaging. CLINICAL FEATURES: The patient suffered for 1 yr from intermittent but progressive pain in his right upper arm and shoulder area. There was no history of trauma or known systemic disease. There was decreased range of motion in abduction of the glenohumeral joint and pain on focal pressure along the deltoid muscle. A complete imaging evaluation consisting of plain film radiography, CT and MRI was performed, which revealed the classical imaging features of an aneurysmal bone cyst. An additional cystic lesion was detected by the MRI that was not appreciated on the plain films or CT. INTERVENTION AND OUTCOME: The patient was referred for biopsy to confirm the preliminary diagnosis of aneurysmal bone cyst. No treatment was instituted. CONCLUSION: Evaluation of aneurysmal bone cyst may be completed with CT scanning and more specifically with MRI MRI coronal T2, weighted images are advantageous for visualization of the main cystic lesion and any additional cysts. Fast field echo images show a better contrast between the cyst and bone marrow with extension of the cyst into the epiphysis as evident in this case. Follow-up studies revealed complete healing of the cyst with only residual densities in the humeral metaphyseal area.

Does carpal canal stenosis predict outcome in women with carpal tunnel syndrome?

OBJECTIVE: We investigated the role of carpal canal stenosis as a predictor of outcome in patients who underwent surgical treatment for carpal tunnel syndrome (CTS). METHODS: We performed magnetic resonance imaging (MRI) of the wrist in 31 female patients with clinically and neurophysiologically confirmed CTS. With a computerized analyser we quantitatively calculated the focal narrowest point of the tunnel. Patient's assessment of CTS-related symptoms were obtained by using a visual analogue scale before, and 6 months after treatment. RESULTS: Seventeen (56%) patients improved in all symptoms after treatment. The focal narrowest point of the tunnel was identified at its distal third in all patients, at 8 mm from the outlet. The median area of the narrowest point in those who improved clinically (n=17) was 238.9 mm2 compared with 269.8 mm2 in others (n=14), P=0.046. CONCLUSION: Identification of carpal canal stenosis may be important in selecting candidates for treatment in symptomatic CTS.

MRI of bilateral bipartite hamulus: a case report.

Normal skeletal variants are a common occurrence in clinical practice and may lead to misinterpretation. As part of a case control study investigating the carpal tunnel, our asymptomatic and voluntary participant underwent magnetic resonance (MR) imaging of both wrists from the metacarpal bases to the distal radiocarpal joint. The imaging techniques included spin echo (SE), turbo spin echo (TSE) and fast field echo (FFE) sequences using 4 mm-slice thickness. As an incidental finding bipartite hamulus was detected bilaterally. The anomaly was evident in both hamuli with similar MRI characteristics. The congenital origin was further supported by the absence of trauma or surgery to the wrists. In this case report the authors discuss the anatomical variant, bilateral bipartite hook of the hamate, and demonstrate the reliability of contiguous slices of MR axial slices in displaying an anatomical variant of the carpus. This normal variant of the hamate is not commonly encountered in MR imaging of the wrist and can be misinterpreted as fracture or post-traumatic sequelae. Images of the normal hamulus are presented for comparison.

MRI of the spine and spinal cord: imaging techniques, normal anatomy, artifacts, and pitfalls.

BACKGROUND: Magnetic resonance imaging (MRI) is widely used to evaluate the spine and spinal cord. OBJECTIVE: In this article, MRI of the spine is discussed in terms of normal anatomy, standard and advanced imaging techniques, general indications, limitations, and potential for the future. DISCUSSION: Although MRI does not provide the high bony detail possible with computed tomography, the appropriate combination of the sequences takes advantage of the different tissue characteristics to discriminate the various bony-and soft-tissue structures of the spine. CONCLUSION: MRI enables the imaging specialist to evaluate a large anatomic region in multiple planes and can better examine the spinal cord.

MR urography in children: current status and future development.

The normal anatomy and many pathologies of the pediatric genitourinary system can be assessed with different imaging modalities. Most of them are based on the use of ionizing radiation and/or invasive techniques. The contribution of magnetic resonance imaging in this regard has opened new ways of approaching pathological conditions in this patient group. The addition of the newly developed rapid techniques has enhanced the superiority of MRI, and both morphological and functional evaluation of the genitourinary system can be achieved. There are different factors on which rely the optimization and the efficiency of magnetic resonance urography (MRU). Of importance is adequate patient immobilization and the use of optimal imaging sequences. The rapid technical development, including the advent of the post-processing respiratory navigator, allows acquisition of high-quality images independent of the patient's respiratory rate. In the future, it is expected that MRU, due to its non-use of ionizing radiation, will become the most important tool in the diagnostic work-up of genitourinary pathologies in infants and small children.

Quantitative MRI analysis of anatomic dimensions of the carpal tunnel in women.

114 wrists from two groups of asymptomatic women of 25-45 years of age (group I, no = 30) and over 45 years (group II, no = 27) were examined: a) to quantify the anatomic features of the carpal tunnel, and b) to search for age-related changes in the anatomy of the tunnel. Bilateral MRI axial wrist images were obtained by means of turbo spin echo (TSE) and fast field echo (FFE) sequences. We measured the length, the cross-sectional areas, the volume of the carpal tunnels-from inlet to outlet- and the volume of the wrists, bilaterally. A carpal tunnel volume/wrist volume (CTV/WV) ratio was obtained in both groups. We also searched for the location of the narrowest point of the canal. The mean (SD) length of the tunnel, from inlet to outlet, was 36.3 mm (SD = 3.4), in both groups. The tunnel had a cone shape, with the inlet constantly larger than the outlet in all subjects. The mean (SD) cross-sectional area of the tunnel inlet was found to be larger in group II, compared to group I (p = 0.029). The calculated mean (SD) volume of the tunnel also appeared significantly larger in the older group (p = 0.023). The narrowest point of the canal was identified at its distal third, at 8 mm from the outlet, in both groups. We conclude that: a) quantitative MRI is a valuable method for assessing the anatomic characteristics of the carpal tunnel, and b) the anatomy of the tunnel is affected by age.

Quantitative cerebral MRI in epileptic patients.

OBJECTIVES: To determine cerebral atrophy parameters on MRI images of epileptic patients. MATERIAL AND METHODS: Examination of the brain was performed in a 0.5 Tesla magnet in 32 women with epilepsy and 36 female healthy controls. Fifteen patients were classified to have generalised epilepsy and 17 had partial seizure onset. Epileptic patients with structural brain changes were excluded. At midsagittal level the area of corpus callosum, cerebrum and cerebellum were selected as atrophy parameters. At transverse level the ventricle-brain ratio (VBR) as a measure of overall cerebral atrophy, bifrontal ratio (BFR) reflecting atrophy in the area of the frontal horns, bicaudate ratio (BCR) and bioccipital ratio (BOR) were calculated to evaluate atrophy in the region of nucleus caudatus as well as in the occipital area. RESULTS: The mean values of VBR were significantly larger in the two epileptic groups than in controls, p = 0.0003. No significant difference in mean VBR were found between focal and generalised seizure onset epilepsy. Also significant decreased cerebellar area on midsagittal section was detected in epileptic patients with partial onset epilepsy compared with controls, p = 0.037. Atrophy was not associated with type and duration of epilepsy, but VBR and age were positively associated in patients with generalised onset seizures. CONCLUSION: These findings suggest general brain atrophy to be present in epileptic patients including those with partial epilepsy. Whether atrophy in epileptic patients occurs as a consequence of disease-related factors like hypoxia or treatment with antiepileptic drugs has to be investigated in a prospectively designed study.

Impact of occupational variables in carpal tunnel syndrome.

OBJECTIVE: We studied the impact of work-related factors on the outcome in patients operated for carpal tunnel syndrome. METHODS: The population consisted of 106 CTS patients who worked at the time of operation. We registered social and occupational data from the patients. RESULTS: Median time of sick leave was 7 weeks for the total group. Sixty-four percent reported a relationship between their work and the disease. Eighty-nine percent of the operated patients returned to their previous work after operation. CONCLUSIONS: A majority of the patients attributed the CTS-related symptoms to their occupation. Work-related factors may therefore be one possible explanation for the socioeconomical consequences of CTS. A permanent drop-out from work in more than 1 out of 10 patients after CTS treatment indicate that CTS form a substantial socioeconomical burden in the society.

Quantitative MRI and electrophysiology of preoperative carpal tunnel syndrome in a female population.

The tunnel size is reported to play a role in median neuropathy. The aim of the study was to quantify the volume of the carpal tunnel in a selected population with idiopathic carpal tunnel syndrome (CTS), as the narrowest point of the canal was noted. Twenty-seven patients with CTS and 28 asymptomatic controls were examined. All participants were women. Both groups underwent nerve conduction studies and magnetic resonance (MR) of the wrists. On the MR axial images, the volume of carpal tunnels, the wrists and the thenar muscles were calculated bilaterally in all subjects. The values for the signal intensity of the median nerve from all wrists were also quantified and correlated with the neurophysiological findings. The carpal tunnel volume (CTV) and the wrist volume (WV)/CTV ratio were almost identical in both groups (p = 0.36 and p = 0.45, respectively). The focal narrowest point of the tunnel was similarly located in both populations, and detected at its distal third, about 8 mm from the outlet. The median nerve in the patients emitted a higher signal compared with the controls, p = 0.037. Between the two groups, there were differences in the amplitude and the distal latency of the median sensory branch (p = 0.0001 and p = 0.0001, respectively), as well as in the amplitude and the F-wave latencies of the median motor branch (p = 0.045 and p = 0.017, respectively). There was no difference in the size of the carpal tunnel in women with idiopathic CTS compared with healthy controls, as the focal narrowest point was equally located in both groups near the canal outlet.

Relationship between brain structure sizes and performing rapid limb movements. A quantitative magnetic resonance study.

In this study, we aimed to determine the relationship between the size of cerebral structures evaluated by quantitative magnetic resonance technique and the ability of performing rapid-velocity limb movements. Forty-seven healthy women with a mean age of 43.4 years (range 22-68) were included. Exclusion criteria were systemic diseases including alcoholism. Finger and ankle tapping were quantitatively recorded for both right and left extremities. A mean value for the right and left side was calculated. To determine atrophy, we measured the area of the corpus callosum, the cerebrum and the cerebellum on midline sagittal sections. On transverse images, the ventricle-to-brain ratio, the bifrontal ratio and the bicaudate ratio were selected as atrophy parameters. Also, the prevalence of white matter hyperintensities was assessed. Fifteen (32%) had hyperintense white matter lesions. Using simple regression analysis, the frequencies of both finger (r = 0.37, beta = -0.002, p = 0.022) and ankle (r = 0.35, beta = -0.001, p = 0.032) tapping were associated with reduced cerebellar size. No association was found for other atrophy parameters or the number of hyperintense white matter lesions. This study indicates that impaired ability to perform fast limb movements may be related to a relative cerebellar atrophy.

[Carpal tunnel syndrome. Comparative studies of pre- and postoperative magnetic resonance and electromyography]. / Le syndrome du canal carpien. Etudes comparatives pré-et postopératoires entre résonance magnétique et électromyographie.

A comparative wrist study was conducted in a total of 36 subjects: 20 normal volunteers and 16 patients with diagnosed carpal tunnel syndrome. 1.5 Tesla MR was used with a cylindrical extremity coll. The authors reviewed the anatomy of the wrist in the normal subjects. The accuracy of MR diagnostic criteria for carpal tunnel syndrome was assessed in comparison with EMG results and surgical findings. The authors conclude that MRI has proved to be reliable and useful in the diagnostic work up of carpal tunnel syndrome. Its main indication would be in cases of negative or doubtful EMG.