[Magnetic resonance imaging for the diagnosis of sacroiliitis in Israel: our experience in the last five years].

PURPOSE: Spondyloarthropathies are characterized by inflammatory involvement of the sacroiliac joints [SIJ] and sacroiliitis is a diagnostic criterion for the disease. Magnetic resonance imaging (MRI) is considered the preferred imaging modality for detection and diagnosis of sacroiliitis in its early stages. We reviewed MRI examinations of the SIJ performed in our institution, evaluated the findings and the change in study prevalence along the years. METHODS: All SIJ MRI studies performed in our institution between 2005-2009 were evaluated in consensus by an intern and a muscutoskeletal staff radiologist. The following findings were registered: Chronic changes: erosions, bony bridges, subchondral sclerosis. Acute findings: bone marrow edema, contrast enhancement. Sacroitiitis was diagnoses based on these findings. The prevalence of SIJ MRI studies was calculated and compared with all musculoskeletal MRI studies performed in these years. RESULTS: A total of 93 SIJ MRI studies were performed between 2005-2009. A gradual increase in the number of studies was detected in these years. The number of SIJ MRI studies performed during 2009, was 8.2 times higher than in 2005, while the increase in musculoskeletal MRI studies was only 2.5 fold (p < 0.001). 53 subjects (57%) were diagnosed with sacroiliitis (male/female: 25/28, average age: 30 years), alternative diagnosis was given in 4 cases and in the rest no abnormality was detected. CONCLUSIONS: SIJ MRI is highly sensitive for inflammatory changes of the sacroiliac joints. Awareness of the important role of this study for early diagnosis and treatment of spondyloarthropathies as expressed in a substantial rise in referrals that has dramatically increased in the last years.

Osteoid osteoma--the CT vessel sign.

OBJECTIVE: To evaluate whether the presence of a feeding vessel in proximity to osteoid osteomas of long bones on multidetector CT (MDCT) can be an adjuvant clue for the diagnosis of osteoid osteoma. MATERIALS AND METHODS: Forty-nine CT scans of patients with radiological and clinical diagnosis of osteoid osteoma of long bones and a control group of 20 CT scans of patients with cortical-based lesions other then osteoid osteoma were analyzed. Two radiologists evaluated the CT images in consensus for the presence of a blood vessel in the same axial slices in which the nidus of osteoid osteoma was seen and to determine the incidence. RESULTS: In 39 cases (79.6%) of osteoid osteoma, a blood vessel either entered the nidus (23 patients) or was seen in proximity to it (16 patients). This was significantly different (P < 0.05) from the cortical-based lesions, in which only two CT scans (10%) showed a blood vessel in the lesion's proximity. CONCLUSION: In the majority of osteoid osteoma lesions in long bones, a blood vessel can be seen on MDCT either entering the nidus itself or in its proximity. The role of this vessel in the lesion pathogenesis and whether it improves diagnostic accuracy need further evaluation.

Is magnetic resonance imaging safe for patients with retained metal fragments from combat and terrorist attacks?

BACKGROUND: Increasing numbers of military confrontations and terrorist attacks have led to increasing reports of retained metal fragments among patients referred for magnetic resonance imaging (MRI). The potential hazard of retained metal fragments for patients undergoing MRI has been studied among patients with retained metal fragments from domestic violence but not from combat and terrorist attacks. PURPOSE: To retrospectively evaluate the safety of MRI in patients with subcutaneous warfare-metal fragments. MATERIAL AND METHODS: 10,322 consecutive metal screening forms of patients scheduled for 1.5 Tesla (T) MR examination were retrospectively reviewed. All patients reported to have retained metal fragments were contacted by telephone and asked to describe the event in which they were exposed to the fragments and for any adverse sequelae or sensations during and after MRI. Their radiographs were evaluated for the number and size of the fragments. The data were analyzed for correlations between these factors. RESULTS: Seven of the 24 patients who reported retained metal fragments were excluded, since there was no validating evidence of their presence. Fragments in the remaining 17 patients (18 MRI examinations) were inflicted by military or terrorist attacks that occurred 2-39 years prior to the MRI. The fragment size ranged between 1 and 10 mm. One patient reported a superficial migration of a 10-mm fragment after MRI. No other adverse reactions were reported. CONCLUSION: Conducting 1.5T MRI examinations is safe in patients with retained metal fragments from combat and terrorist attacks not in the vicinity of vital organs. However, caution is advised.

[Percutaneous CT guided radio-frequency ablation of osteoid osteoma and osteoblastoma].

BACKGROUND: Osteoid osteoma (OO) is a benign osteoblastic bone lesion that causes severe local pain mainly at night, and usually responds to oral administration of NSAID. The lesion is located around the proximal thigh in more than 50% of the cases. Osteoblastoma is similar to OO in their histopathology features, but emerges frequently in the spine, and has a larger diameter than OO. Percutaneous CT-guided radiofrequency ablation (RFA) is becoming the treatment of choice for osteoid osteoma and non-aggressive osteoblastoma in the last decade. METHODS: During the period 2005-2009, 38 patients were diagnosed with osteoid osteoma (n = 34), and osteoblastoma (n = 4). A total of 34 patients were treated with RFA using a water-cooled, variable ablation size tip. Two patients underwent an open procedure, and 2 had spontaneous remission. RESULTS: Thirty three patients (97%) reported complete remission of their pain after a single treatment; one patient needed a second RFA treatment, and reported full remission of his symptoms after the 2nd treatment. CONCLUSIONS: Percutaneous CT-guided radiofrequency ablation of osteoid osteoma and non-aggressive osteoblastoma is simple, safe, and reliable. Meticulous placement of the probe inside the tumor, and the usage of water-cooled, variable ablation size tip, improves the overall outcome and decrease complication rates.

Pain palliation in patients with bone metastases using MR-guided focused ultrasound surgery: a multicenter study.

BACKGROUND: Noninvasive thermal ablation using magnetic resonance (MR)-guided focused ultrasound (MRgFUS) has been shown to be clinically effective in uterine fibroids, and is being evaluated for ablation of breast, liver, and brain lesions. Recently MRgFUS has been evaluated for palliation of pain caused by bone metastases. We present the clinical results of a multicenter study using MRgFUS for palliation of bone metastases pain. METHODS: A multicenter study to evaluate the safety and efficacy of MRgFUS palliative treatment of bone metastases was conducted in patients suffering from painful metastatic bone lesions for which other treatments were either ineffective or not feasible. Thirty-one patients with painful bone metastases underwent the MRgFUS procedure in three medical centers. Treatment safety was evaluated by assessing the device-related complications. Effectiveness of pain palliation was evaluated using the visual analog pain score (VAS), and measurable changes in the intake of opioid analgesics. RESULTS: Thirty-six procedures were performed on 31 patients. Mean follow-up time was 4 months. 25 patients underwent the planned treatment and were available for 3 months post-treatment follow-up. 72% of the patients (18/25) reported significant pain improvement. Average VAS score was reduced from 5.9 prior to treatment to 1.8 at 3 months post treatment. 67% of patients with recorded medication data reported a reduction in their opioid usage. No device-related severe adverse events were recorded. CONCLUSION: The results suggest that MRgFUS has the ability to provide an accurate, effective, and safe noninvasive palliative treatment for patients with bone metastases.

Strains and stresses in sub-dermal tissues of the buttocks are greater in paraplegics than in healthy during sitting.

A pressure-related deep tissue injury (DTI) is a severe pressure ulcer, which initiates in muscle tissue overlying a bony prominence (e.g. the ischial tuberosities, IT) and progresses outwards through fat and skin, unnoticed by the paralyzed patient. We recently showed that internal strains and stresses in muscle and fat of individuals at anatomical sites susceptible to DTI can be evaluated by integrating Open-MRI scans with subject-specific finite element (FE) analyzes (Linder-Ganz et al., Journal of Biomechanics, 2007); however, sub-dermal soft tissue strains/stresses from paraplegics are still missing in literature. We hypothesize that the pathoanatomy of the buttocks in paraplegia increases the internal soft tissue loads under the IT, making these patients inherently susceptible to DTI. We hence compared the strain and stress peaks in the gluteus muscle and fat tissues under the IT of six healthy and six paraplegic patients, using the coupled MRI-FE method. Peak principal compression, principal tension, von Mises and shear strains in the gluteus were 1.2-, 3.1-, 1.4- and 1.4-fold higher in paraplegics than in healthy, respectively (p<0.02). Likewise, peak principal compression, principal tension, von Mises and shear stresses in the gluteus were 1.9-, 2.5-, 2.1- and 1.7-fold higher for the paraplegics (p<0.05). Peak gluteal compression and shear stresses decreased by as much as 70% when the paraplegic patients moved from a sitting to a lying posture, indicating on the effectiveness of recommending such patients to lie down after prolonged periods of sitting. This is the first attempt to compare internal soft tissue loads between paraplegic and healthy subjects, using an objective standardized bioengineering method of analysis. The findings support our hypothesis that internal tissue loads are significantly higher in paraplegics, and that postural changes significantly affect these loads. The method of analysis is useful for quantifying the effectiveness of various interventions to alleviate sub-dermal tissue loads at sites susceptible to pressure ulcers and DTI, including cushions, mattresses, recommendations for posture and postural changes, etc.

Assessment of mechanical conditions in sub-dermal tissues during sitting: a combined experimental-MRI and finite element approach.

A common but potentially severe malady afflicting permanent wheelchair users is pressure sores caused by elevated soft tissue strains and stresses over a critical prolonged period of time. Presently, there is paucity of information regarding deep soft tissue strains and stresses in the buttocks of humans during sitting. Strain and stress distributions in deep muscle and fat tissues were therefore calculated in six healthy subjects during sitting, in a double-donut Open-MR system, using a "reverse engineering" approach. Specifically, finite element (FE) models of the undeformed buttock were built for each subject using MR images taken at the coronal plane in a non-weight-bearing sitting posture. Using a second MR image taken from each subject during weight-bearing sitting we characterized the ischial tuberosity sagging toward the sitting surface in weight-bearing, and used these data as displacement boundary conditions for the FE models. These subject-specific FE analyses showed that maximal tissue strains and stresses occur in the gluteal muscles, not in fat or at the skin near the body-seat interface. Peak principal compressive strain and stress in the gluteus muscle were 74+/-7% and 32+/-9 kPa (mean+/-standard deviation), respectively. Peak principal compressive strain and stress in enveloping fat tissue were 46+/-7% and 18+/-4 kPa, respectively. Models were validated by comparing measured peak interface pressures under the ischial tuberosities (17+/-4 kPa) with those calculated by means of FE (18+/-3 kPa), for each subject. This is the first study to quantify sub-dermal tissue strain and stress distributions in sitting humans, in vivo. These data are essential for understanding the aetiology of pressure sores, particularly those that were recently termed "deep tissue injury" at the US National Pressure Ulcer Advisory Panel (NPUAP) 2005 Consensus Conference.

Sonographically guided hydrostatic reduction of intussusception in children.

PURPOSE: The aim of this study was to assess the efficacy of sonographically guided hydrostatic enema in therapeutic reduction of intussusception in children and to determine whether certain factors may predict the outcome of this technique. METHODS: We retrospectively reviewed the medical records and sonographic examinations of 83 consecutive children sonographically diagnosed with 101 cases of intussusception over a 40-month period. In 99 cases, sonographically guided hydrostatic reduction was attempted. The presence of free peritoneal fluid, the presence of fluid inside the intussusception, and the initial location of the intussusception, as confirmed by sonography, along with the level of experience of the radiologist who performed the reduction were statistically analyzed to determine their effect on outcome. A p value less than 0.05 was considered significant. RESULTS: In 88 (89%) of the 99 cases, hydrostatic reduction was successful. No complications during or after hydrostatic enema were noted. The success rate was significantly lower among patients whose intussusception was located in the left side of the abdomen (p < 0.01) or contained entrapped fluid (p < 0.02) or those in whom hydrostatic reduction was not performed by an experienced sonologist (p < 0.01). The presence of free peritoneal fluid was not a predictor of outcome (p > 0.1). No complications during or after hydrostatic enema were noted. CONCLUSIONS: Sonographically guided hydrostatic reduction of intussusception is safe and effective. We recommend that this method be attempted before surgery is considered, even in cases in which the intussusception contains entrapped fluid or is located in the left side of the abdomen. The level of experience of the radiologist who performs the reduction significantly affects the results of this procedure and should be carefully considered, particularly in cases in which initial sonography reveals the presence of risk factors.