In vivo DTI longitudinal measurements of acute sciatic nerve traction injury and the association with pathological and functional changes

Objective

To explore the feasibility of longitudinally measuring acute traction injury to the sciatic nerve using 1.5 T clinical MRI scanner of diffusion tensor imaging (DTI) and to analyze the associations of the measurements [regarding fractional anisotropy (FA), apparent diffusion coefficient (ADC), eigenvalue (λ_|| and λ_⊥)] with limb function and pathology.

Materials and methods

Acute traction injuries to the sciatic nerve were created in the right hind limbs of 32 New Zealand white rabbits, the left hind limbs were chosen as sham operation nerves. MRI scans were performed at intervals from pre-operation through 8 weeks post-operation follow up. Scanning sequences included T2WI, STIR, and single shot spin echo DTI with single shot EPI acquisition (SE-DTI-SSEPI). Parameters of FA, ADC, axial diffusivity (λ_||) and radial diffusivity (λ_⊥) were then calculated from the DTI. The limb functions and pathologic changes were evaluated and compared.

Results

Diffusion Tensor Tractography (DTT) only revealed the proximal portion of the injured nerves 1–3 days after traction injury but did not reveal the nerve of the distal and traction portions at all. Nerve fibers of the distal and traction portions were not revealed by DTT until after the 1st week. They were elongated gradually and recovered almost to the normal at 8th week. The value of FA and λ_⊥of the injured nerves, which varied in different portions, were significantly different between the traction injury nerves and the sham operation nerves, whereas the value of ADC and λ_|| were not significantly different. The curve lines of FA value-time for the proximal, traction and distal portions of the injured nerve correlated well to the functional and pathological changes of the limb affected, while the DTI parameters did not change that much in the sham-operated nerves.

Conclusions

DTI obtained on a 1.5 T clinical MRI scanner can demonstrate early abnormal changes following traction injury to the sciatic nerve in rabbits. The curve lines of FA-time and λ_⊥-time for nerve traction injury are consistent with the pathological and functional changes of the limb affected. DTI may thus be a sensitive and reliable method to evaluate degeneration and regeneration of the nerve after traction injury.     

In vivo MR imaging tracking of transplanted mesenchymal stem cells in a rabbit model of acute peripheral nerve traction injury

Purpose

To investigate in vivo MRI tracking mesenchymal stem cells (MSCs) in peripheral nerve injures using a clinically available paramagnetic contrast agent (Gd‐DTPA) and commercially available rhodamine‐incorporated transfection reagents (PEI‐FluoR).

Materials and Methods

After bone marrow MSCs were labeled with Gd‐DTPA and PEI‐FluoR complex, the labeling efficacy and longevity of Gd‐DTPA maintenance were measured and cell viability, proliferation, and apoptosis were assessed. Thirty‐six rabbits with acute sciatic nerve traction injury randomly received 1 × 10⁶ labeled (n = 12) or unlabeled MSCs (n = 12) or vehicle alone injection. The distribution and migration of implanted cells was followed by MRI and correlated with histology. The relative signal intensity (RSL) of the grafts was measured.

Results

The labeling efficiency was 76 ± 4.7% and the labeling procedure did not in?uence cell viability, proliferation, and apoptosis. A persistent higher RSL in grafts was found in the labeled group compared with the unlabeled and vehicle groups until 10 days after transplantation (P < 0.05). The distribution and migration of labeled cells could be tracked by MRI until 10 days after transplantation. Transplanted MSCs were not found to transdifferentiate into Schwann‐like cells within 14‐day follow‐up.

Conclusion

Labeling MSCs with the dual agents may enable cellular MRI of the engraftment in the experimental peripheral nerve injury. J. Magn. Reson. Imaging 2010;32:1076–1085. © 2010 Wiley‐Liss, Inc.

     

In vivo assessment of peripheral nerve regeneration by diffusion tensor imaging

Purpose

To evaluate the sensitivity of diffusion tensor imaging (DTI) in assessing peripheral nerve regeneration in vivo. We assessed the changes in the DTI parameters and histological analyses after nerve injury to examine degeneration and regeneration in the rat sciatic nerves.

Materials and Methods

For magnetic resonance imaging (MRI), 16 rats were randomly divided into two groups: group P (permanently crushed; n = 7) and group T (temporally crushed; n = 9). Serial MRI of the right leg was performed before the operation, and then performed at the timepoints of 1, 2, 3, and 4 weeks after the crush injury. The changes in fractional anisotropy (FA), axial diffusivity (λ_∥), and radial diffusivity (λ_?) were quantified. For histological analyses, the number of axons and the myelinated axon areas were quantified.

Results

Decreased FA and increased λ_? were observed in the degenerative phase, and increased FA and decreased λ_? were observed in the regenerative phase. The changes in FA and λ_? were strongly correlated with histological changes, including axonal and myelin regeneration.

Conclusion

DTI parameters, especially λ_?, can be good indicators for peripheral nerve regeneration and can be applied as noninvasive diagnostic tools for a variety of neurological diseases. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.

     

Non-perforating small bowel Crohn's disease assessed by MRI enterography: derivation and histopathological validation of an MR-based activity index

Objectives

To develop and validate a qualitative scoring system for enteric Crohn's disease activity using MR enterography (MRE).

Methods

MRE was performed in 16 patients (mean age 33, 8 male) undergoing small bowel resection. Mural thickness, T2 signal, contrast enhancement, and perimural oedema were scored qualitatively (0–3) at 44 locations. Transmural histopathological scoring of acute inflammation (AIS) was performed at all locations (score 0–13). MRI parameters best predicting AIS were derived using multivariate analysis. The MRI activity index was applied to 26 Crohn's patients (mean age 32, range 13–69 years, 15 male) and correlated to terminal ileal biopsy scores of acute inflammation (“eAIS” score 1–6). Receiver operator characteristic curves were calculated.

Results

Mural thickness (coefficient 1.34 (95% CI 0.36, 2.32)], p = 0.007) and T2 signal (coefficient 0.90 (95% CI −0.24, 2.04) p = 0.06) best predicted AIS (AIS = 1.79 + 1.34*mural thickness + 0.94*mural T2 score [R-squared 0.52]). There was a significant correlation between the MRI index and eAIS (Kendall's tau = 0.40, 95% CI 0.11–0.64, p = 0.02). The model achieved a sensitivity of 0.81 (95% CI 0.54–0.96), specificity of 0.70 (0.35–0.93) and AUC 0.77 for predicting acute inflammation (eAIS ≥2).

Conclusions

A simple qualitative MRI Crohn's disease activity score appears predictive against a histopathological standard of reference.     

Magnetic resonance imaging evaluation of acute crush injury of rabbit sciatic nerve: correlation with histology

OBJECTIVE: To investigate the relation between the quantitative assessment of magnetic resonance imaging (MRI) features and the correlation with histology and functional recovery by using the rabbit sciatic nerve crush model. METHODS: In New Zealand, 32 rabbits were randomly divided into 2 groups (group A and B); all rabbits underwent crushing injury of their left sciatic nerve. In group A (n = 16), the sciatic nerves were crushed by using microvessel clamps with a strength of 3.61 kg. In group B (n = 16), the sciatic nerves were crushed with a strength of 10.50 kg. Right sciatic nerves were served as controls. Serial MRI of both hind limbs in each rabbit was performed before and at the time point of 1, 2, 4, and 8 weeks after crushed injury. The MRI protocol included T1-weighted spin-echo (T1WI), 3 dimension turbo spin-echo T2-weighted (3DT2WI), T2-weighted turbo spin-echo images with spectral presaturation with inversion recovery (T2WI/SPIR), balanced fast-field echo (B-FFE) and short-time inversion recovery (STIR) sequences. The coronal image of the sciatic nerve was obtained. The nerve and muscle signal ratio (SIR) on each sequence was measured. The function recovery was observed and pathological examination was performed at each time point. RESULTS: A signal intensity increase of the distal segment of crushed sciatic nerves was found on 3DT2WI, T2WI/SPIR, B-FFE, and STIR, but not on T1WI images. Of 32 crushed nerves, 30 nerves showed high signal intensity. The correct diagnostic rate was 93.75% with false negative-positive of 6.25%. The SIR of the crushed sciatic nerve at distal portion was higher than those of the control nerves; there was a statistically significant difference (P < 0.001). The SIR of the distal portion of crushed nerves was higher than that of the proximal nerve portion; there was a statistically significant difference (P < 0.001). Whereas, the SIR at proximal nerve portions of crushed nerve was similar to control nerves (P > 0.05). The SIR between group A and group B was not found statistically significantly different (P > 0.05). The SIR of crushed nerves at distal portion increased at one week after the crush injury, subsequently further increased, and reached a maximum at 2 weeks. The pathological examination revealed myelin swelling and axonal fragmentation of crushed nerve. Abduction function of injured hind limb was deficit. From 4 to 8 weeks following the crush, the SIR decreased, correspondingly, nerve regeneration was revealed on pathology including extensive Schwann cells proliferation and the immature myelin formation. The abduction function gradually recovered. There was no abnormal finding on MRI for control and sham-operated nerves. CONCLUSION: The SIR of injured nerve at distal portion increased on MRI. The evolution of SIR after injury was correlated with the degeneration and regeneration of nerve and the function recovery of lower extremities. Assessment of peripheral nerve injury by using SIR could reveal acute nerve injury, as well as aid in monitoring the recovery process. The pathophysiological basis for the SIR is predominantly the results of axon breakdown and myelin regeneration     

Feasibility Study on MR-Guided High-Intensity Focused Ultrasound Ablation of Sciatic Nerve in a Swine Model: Preliminary Results

Introduction

Spastic patients often seek neurolysis, the permanent destruction of the sciatic nerve, for better pain management. MRI-guided high-intensity focused ultrasound (MRgHIFU) may serve as a noninvasive alternative to the prevailing, more intrusive techniques. This in vivo acute study is aimed at performing sciatic nerve neurolysis using a clinical MRgHIFU system.

Methods

The HIFU ablation of sciatic nerves was performed in swine (n = 5) using a HIFU system integrated with a 3 T MRI scanner. Acute lesions were confirmed using T1-weighted contrast-enhanced (CE) MRI and histopathology using hematoxylin and eosin staining. The animals were euthanized immediately following post-ablation imaging.

Results

Reddening and mild thickening of the nerve and pallor of the adjacent muscle were seen in all animals. The HIFU-treated sections of the nerves displayed nuclear pyknosis of Schwann cells, vascular hyperemia, perineural edema, hyalinization of the collagenous stroma of the nerve, myelin sheet swelling, and loss of axons. Ablations were visible on CE MRI. Non-perfused volume of the lesions (5.8–64.6 cc) linearly correlated with estimated lethal thermal dose volume (4.7–34.2 cc). Skin burn adjacent to the largest ablated zone was observed in the first animal. Bilateral treatment time ranged from 55 to 138 min, and preparation time required 2 h on average.

Conclusion

The acute pilot study in swine demonstrated the feasibility of a noninvasive neurolysis of the sciatic nerve using a clinical MRgHIFU system. Results revealed that acute HIFU nerve lesions were detectable on CE MRI, gross pathology, and histology.

     

MR imaging of acute pancreatitis: Correlation of abdominal wall edema with severity scores

Objective

To study MRI findings of abdominal wall edema (AWE) in acute pancreatitis as well as correlations between AWE and the severity of acute pancreatitis according to the MR severity index (MRSI) and the Acute Physiology And Chronic Healthy Evaluation III (APACHE III) scoring system.

Materials and methods

A total of 160 patients with AP admitted to our institution between December 2009 and March 2011 were included in this study. MRI was performed within 48 h after admission. MRI findings of acute pancreatitis were noted, including AWE on the MRI. The abdominal wall area was divided into quarters, and each area involved was recorded as 1 point to score the severity of AWE. The severity of acute pancreatitis was studied using both the MRSI and the APACHE III scoring system. Spearman correlation of AWE with the MRSI and the APACHE III scoring system was analyzed.

Results

In 160 patients with acute pancreatitis, 53.8% had AWE on MRI. The average AWE score was 1.2 ± 1.4 points. The prevalence of AWE was 30.5%, 64.5% and 100% in mild, moderate and severe AP, respectively, according to MRSI. AWE on MRI was correlated with MRSI scores (r = 0.441, p = 0.000). According to APACHE III scores, the averages were 2.0 ± 1.1 and 2.6 ± 1.1 points in mild AP and severe AP, respectively (P = 0.016). AWE was slightly correlated with the APACHE III scores (r = 0.222, p = 0.005).

Conclusion

AWE on MRI in acute pancreatitis is common, which may be a supplementary indicator in determining the severity of AP.     

Measurement of tumor size in adult glioblastoma: Classical cross-sectional criteria on 2D MRI or volumetric criteria on high resolution 3D MRI?

Objective

To investigate the added value of volume on post-contrast three dimensional (3D) T1-weighted image (T1WI) over classical cross-sectional area on two dimensional (2D) T1WI in evaluating tumor response in glioblastoma multiforme (GBM).

Methods

Tumor cross-sectional area and volume measurements were performed on 104 MRI studies from 42 adult patients with GBM on post-contrast 5 mm 2D T1WI and isotropic high resolution 3D T1WI, respectively. 52 pairs of MRI scans were analyzed for relative change. Radiographic responses were determined based on change in either area or volume.

Results

A high correlation was revealed between tumor size measured by area on thick 2D and volume on high resolution 3D MRI in 104 scans (r = 0.82, p < 0.001). When four tumor response criteria were used according to the percentage changes (complete response/partial response/stable disease/progression), the kappa coefficient between the area on 2D and volume on 3D was 0.68 (p < 0.05) with an overall agreement of 81%.

Conclusions

Tumor cross-sectional area on post-contrast 2D T1WI appears comparable to volume on 3D T1WI and should still be a practical alternate of volume on 3D for evaluating tumor response.     

MR neurography of the median nerve at 3.0T: optimization of diffusion tensor imaging and fiber tractography

Objectives

The purpose of this study was to systematically assess the optimal b-value and reconstruction parameters for DTI and fiber tractography of the median nerve at 3.0 T.

Methods

Local ethical board approved study with 45 healthy volunteers (15 men, 30 women; mean age, 41 ± 3.4 years) who underwent DTI of the right wrist at 3.0 T. A single-shot echo-planar-imaging sequence (TR/TE 10123/40 ms) was acquired at four different b-values (800, 1000, 1200, and 1400 s/mm²). Two independent readers performed post processing and fiber-tractography. Fractional anisotropy (FA) maps were calculated. Fiber tracts of the median nerve were generated using four different algorithms containing different FA thresholds and different angulation tolerances. Data were evaluated quantitatively and qualitatively.

Results

Tracking algorithms using a minimum FA threshold of 0.2 and a maximum angulation of 10° were significantly better than other algorithms. Fiber tractography generated significantly longer fibers in DTI acquisitions with higher b-values (1200 and 1400 s/mm² versus 800 s/mm²; p < 0.001). The overall quality of fiber tractography was best at a b-value of 1200 s/mm² (p < 0.001).

Conclusions

In conclusion, our results indicate use of b-values between 1000 and 1400 s/mm² for DTI of the median nerve at 3.0 T. Optimal reconstruction parameters for fiber tractography should encompass a minimum FA threshold of 0.2 and a maximum angulation tolerance of 10.     

Assessment of cartilage repair after chondrocyte transplantation with a fibrin-hyaluronan matrix--correlation of morphological MRI, biochemical T2 mapping and clinical outcome

Objective

To evaluate change over time of clinical scores, morphological MRI of cartilage appearance and quantitative T2 values after implantation with BioCart™II, a second generation matrix-assisted implantation system.

Methods

Thirty-one patients were recruited 6–49 months post surgery for cartilage defect in the femoral condyle. Subjects underwent MRI (morphological and T2-mapping sequences) and completed the International Knee Documentation Committee (IKDC) questionnaire. MRI scans were scored using the MR Observation of Cartilage Repair Tissue (MOCART) system and cartilage T2-mapping values were registered.Analysis included correlation of IKDC scores, MOCART and T2 evaluation with each other, with implant age and with previous surgical intervention history.

Results

IKDC score significantly correlated with MOCART score (r = −0.39, p = 0.031), inversely correlated with previous interventions (r = −0.39, p = 0.034) and was significantly higher in patients with longer follow-up time (p = 0.0028).MOCART score was slight, but not significantly higher in patients with longer term implants (p = 0.199).T2 values were significantly lower in patients with longer duration implants (p < 0.001). This trend was repeated in patients with previous interventions, although to a lesser extent.

Conclusions

Significant improvement with time from BioCart™II implantation can be expected by IKDC scoring and MRI T2-mapping values. Patients with previous knee operations can also benefit from this procedure.     

Age-related changes in normal adult pancreas: MR imaging evaluation

Objective

To investigate age-related changes in normal adult pancreas as identified by magnetic resonance imaging (MRI).

Materials and methods

We examined 115 patients without pancreatic diseases (21–90 years) who underwent upper abdominal MRI to evaluate the normal pancreatic MRI findings related to aging. The parameters examined were the pancreatic anteroposterior (AP) diameter, pancreatic lobulation, pancreatic signal intensity (SI), depiction of the main pancreatic duct (MPD), grade of the visual SI decrease on the opposed-phase T1-weighted images compared with in-phase images, and enhancement effect of the pancreas in the arterial phase of dynamic imaging.

Results

The pancreatic AP diameter significantly reduced (head, p = 0.0172; body, p = 0.0007; tail, p < 0.0001), and lobulation (p < 0.0001) and parenchymal fatty change (p < 0.0001) became more evident with aging. No significant correlation was observed between aging and pancreatic SI, however the SI on the in-phase T1-weighted images tended to decrease with aging. No significant correlation was observed between aging and the depiction of the MPD as well as aging and contrast enhancement.

Conclusion

MRI findings of pancreatic atrophy, lobulation, and fatty degeneration are characteristic changes related to aging, and it is necessary to recognize these changes in the interpretation of abdominal MRI in patients with and without pancreatic disease.     

Assessment of liver tumor response by high-field (3T) MRI after radiofrequency ablation: Short- and mid-term evolution of diffusion parameters within the ablation zone

Purpose

To compare the apparent diffusion coefficient (ADC) values of malignant liver lesions on diffusion-weighted MRI (DWI) before and after successful radiofrequency ablation (RF ablation).

Materials and methods

Thirty-two patients with 43 malignant liver lesions (23/20: metastases/hepatocellular carcinomas (HCC)) underwent liver MRI (3.0 T) before (<1 month) and after RF ablation (at 1, 3 and 6 months) using T2-, gadolinium-enhanced T1- and DWI-weighted MR sequences. Jointly, two radiologists prospectively measured ADCs for each lesion by means of two different regions of interest (ROIs), first including the whole lesion and secondly the area with the visibly most restricted diffusion (MRDA) on ADC map. Changes of ADCs were evaluated with ANOVA and Dunnett tests.

Results

Thirty-one patients were successfully treated, while one patient was excluded due to focal recurrence. In metastases (n = 22), the ADC in the whole lesion and in MRDA showed an up-and-down evolution. In HCC (n = 20), the evolution of ADC was more complex, but with significantly higher values (p = 0.013) at 1 and 6 months after RF ablation.

Conclusion

The ADC values of malignant liver lesions successfully treated by RF ablation show a predictable evolution and may help radiologists to monitor tumor response after treatment.     

Comparison of diagnostic accuracy of Magnetic Resonance Imaging and Multidetector Computed Tomography in the detection of pelvic fractures

Objective

To compare diagnostic accuracy and interobserver reliability of Magnetic Resonance Imaging (MRI) and Multidetector Computed Tomography (MDCT) in the detection of acute pelvic fractures.

Materials and methods

In 38 consecutive patients (mean age 74.7 years) with a positive finding of anterior pelvis fracture in the conventional X-rays, pelvic MRI and MDCT were performed for further evaluation of pelvic ring fractures. Two radiologists independently read all data sets. Sensitivity and specificity were calculated based on mean scores for each method. Sensitivities of CT and MRI were compared using a paired proportion test (McNemar). Diagnostic validity of both methods was assessed by the interobserver variability using kappa statistics. Combined clinical data and findings from all imaging studies served as the reference standard.

Results

122 fractures were identified in the reference standard (37 sacral, 58 pubic, 22 acetabular, 1 ischial, 4 ilial). On average, MRI detected 96.3% whereas CT detected 77% of all fractures. With regard to sensitivity, MRI proved to be significantly better compared to MDCT (observer 1, p = 0.0009; observer 2, p = 0.0003 by observer 2). In particular, MRI performed better in the depiction of sacral fractures, reaching a sensitivity of 98.6% compared to 66.1% at CT. The interobserver variability was determined to be very good (k = 0.955 for MRI and 0.902 for MDCT).

Conclusion

MRI reaches a significantly higher sensitivity than CT in the detection of acute pelvic fractures, particularly of the sacrum. Especially in elderly patients with suspicion of a sacral fracture and negative results at MDCT, MRI may be considered as the next step in diagnostic workup.     

1.5T conventional MR-guided iodine-125 interstitial implants for hepatocellular carcinoma: feasibility and preliminary clinical experience

Purpose

To evaluate the feasibility and therapeutic efficacy of 1.5 T conventional MR-guided percutaneous interstitial implantation of I-125 radioactive seeds in patients with hepatocellular carcinoma (HCC).

Materials and methods

The institutional ethics committee approved this study. After imformed consent was obtained, twenty-three patients suffering from a total of 65 HCC lesions were treated with I-125 seed permanent interstitial implantation under the guidance of a 1.5 T conventional magnetic resonance imaging (MRI) system. The FSE T2WI, T1 FSPGR, FIESTA 2D, 3D Dyn T1WI sequences were used to guide an 18G MR-compatible needle inserted into the lesions to introduce the I-125 seeds. The response evaluation criteria in solid tumors (RECIST) were used to evaluate the curative effect.

Results

The needle and I-125 seed were seen clearly on MRI images. The final dose delivered to total decay was 173.46 ± 32.44 Gy (range, 110–270 Gy) as calculated by postoperative TPS. The complete response (CR) was seen in 22 lesions (33.8%), partial response (PR) in 24 lesions (36.9%), stable disease (SD) in 9 lesions (13.8%), and progressive disease (PD) in 10 lesions (15.4%). The post-operative alpha-fetoprotein (AFP) was decreased (t = 3.117, P = 0.005 < 0.05). Two patients were observed a small area of subcapsular bleeding that did not lead to any symptoms or clinical sequelae.

Conclusion

MR-guided I-125 implantation for HCC is technically feasible and effective.     

Assessment of ablative margin after radiofrequency ablation for hepatocellular carcinoma; comparison between magnetic resonance imaging with ferucarbotran and enhanced CT with iodized oil deposition

Background and purpose

Our aim was to investigate whether magnetic resonance imaging (MRI) with ferucarbotran administered prior to radiofrequency ablation could accurately assess ablative margin when compared with enhanced computed tomography (CT) with iodized oil marking.

Materials and methods

We enrolled 27 patients with 32 hepatocellular carcinomas in which iodized oil deposits were visible throughout the nodule after transcatheter arterial chemoembolization. For these nodules, radiofrequency ablation was performed after ferucarbotran administration. We then performed T2-weighted MRI after 1 week and enhanced CT after 1 month. T2-weighted MRI demonstrated the ablative margin as a low-intensity rim. We classified the margin into three grades; margin (+): high-intensity area with a continuous low-intensity rim; margin zero: high-intensity area with a discontinuous low-intensity rim; and margin (−): high-intensity area extending beyond the low-intensity rim.

Results

In 28 (86%) of 32 nodules, there was agreement between MRI and CT. The overall agreement between for the two modalities in the assessment of ablative margin was good (κ = 0.759, 95% confidence interval: 0.480–1.000, p < 0.001). In four nodules, ablative margins on MRI were underestimated by one grade compared with CT.

Conclusion

MRI using ferucarbotran is less invasive and allows earlier assessment than CT. The MRI technique performed similarly to enhanced CT with iodized oil marking in evaluating the ablative margin after radiofrequency ablation.     

Tuberculosis versus lymphoma in the abdominal lymph nodes: a comparative study using contrast-enhanced MRI

Purpose

The purpose of this study was to determine the differential characteristics on MRI between tuberculosis and lymphoma in abdominal lymph nodes.

Materials and methods

We conducted a retrospective analysis for the counter, size, signal intensity, enhancement patterns, and anatomic distribution of lymph nodes in 57 consecutive patients with documented tuberculosis (28 patients; 49.1%) and newly diagnosed, untreated lymphoma (29 patients; 50.9%).

Results

Twenty-four cases (85.7%) in the tuberculosis group were hyperintense on T2-weighted images and either hypointense or isointense on T1-weighted images with respect to the abdominal wall muscle. All cases in the lymphoma group were hyperintense on T2-weighted images and isointense on T1-weighted images with respect to the abdominal wall muscle. Concerning the main anatomic distribution of lymph nodes, the lymph nodes in the lower paraaortic region were more frequently involved in the lymphoma group (48.3%) than in tuberculosis (17.9%, p < 0.05). Moreover, mesenteric lymph nodes were more often involved in tuberculosis (32.1%) than in lymphoma (6.9%, p < 0.05). Tuberculous lymphadenopathy showed predominantly peripheral enhancement, frequently with a multilocular appearance; whereas lymphomatous adenopathy often demonstrated uniform homogeneous enhancement (all p < 0.001).

Conclusion

Contrast-enhanced MRI can be useful in differentiation between these two entities.     

MR findings of Rosai-Dorfman disease in sellar and suprasellar region

Background

Rosai–Dorfman disease (RDD) in sellar/suprasellar region is a rare intracranial disorder. The diagnostic evaluation of this condition using magnetic resonance imaging (MRI) has seldom been described previously. The purpose of our study was to describe MRI characteristics of sellar/suprasellar region RDD.

Methods

Five patients with proved sellar/suprasellar region RDD from May 2005 to March 2010 were retrospectively reviewed. All the patients had undergone magnetic resonance scanning. The number, location, signal intensity (SI), and enhancement pattern of the lesions on MRI were retrospectively evaluated.

Results

Pathological diagnosis of RDD was achieved in all 5 cases including 4 by surgery and 1 by biopsy. The most common presenting symptoms were headache (n = 4) and blurred vision (n = 3). On MRI, isolated suprasellar lesion was found in 2 cases. Suprasellar lesion combined with intrasellar, dural, intra-axial and orbital lesions was found in 3 cases. All lesions showed homogeneous isointense SI on T1-weighted images and hypointense to isointense SI on T2-weighted images except one lesion in the midbrain with slight hyperintense SI on T2-weighted images. All lesions showed homogeneous enhancement.

Conclusion

Homogenously enhancing sellar/suprasellar masses of hypointense to isointense SI on T2-weighted images are suggestive of RDD, and central hypointensity on T2-weighted images may be a specific finding. Intra-axial and extra-axial involvements may coexist with sellar/suprasellar region RDD. Although radiological findings can provide some evidence for this rare entity, differential diagnosis is still needed.     

Renal and perirenal space involvement in acute pancreatitis: An MRI study

Objectives

To study the prevalence and characteristics of renal and perirenal space involvement and its relation to the severity of acute pancreatitis (AP) using MRI.

Methods

115 patients with AP who underwent MRI with the clinical kidney function test were retrospectively analyzed in this study. MRI sequences included conventional and diffusion weighted imaging (DWI) sequences. The renal and perirenal space involvement in AP was noted on MRI. The renal apparent diffusion coefficient (ADC) on DWI was measured for each kidney. The severity of AP on MRI was graded using MR severity index (MRSI). The relationships among the renal and perirenal space involvement on MRI, the renal ADC, MRSI and the results of the kidney function test were analyzed.

Results

In the 115 patients with AP, the renal and perirenal space abnormalities detected included renal parenchymal abnormalities (0.8%), abnormalities of the renal collecting system (2.6%), renal vascular abnormalities (1.7%), thickened renal fascia (99%), perirenal stranding (62%) and perirenal fluid collection (40%). The prevalence of perirenal space abnormalities was correlated with the severity of AP based on MRSI (P < 0.05). The renal ADC values were lower in patients with abnormal kidney function than in those without kidney injury (P < 0.05). The prevalence of kidney function abnormalities was 9.4%, 32% and 100% in mild, moderate, and severe AP cases, respectively (P = 0.00).

Conclusion

Perirenal space involvement is much more than renal parenchymal involvement in AP. The prevalence of perirenal space involvement in AP on MRI has a positive correlation with the severity of AP according to MRSI.     

Automated volumetric assessment of the Achilles tendon (AVAT) using a 3D T2 weighted SPACE sequence at 3T in healthy and pathologic cases

Purpose

Achilles tendinopathy has been reported to be frequently associated with increasing volume of the tendon. This work aims at reliable and accurate volumetric quantification of the Achilles tendon using a newly developed contour detection algorithm applied on high resolution MRI data sets recorded at 3 T.

Materials and methods

A total of 26 healthy tendons and 4 degenerated tendons were examined for this study. Automated identification (AI) of tendon boundaries was performed in transverse slices with isotropic resolution (0.8 mm) gained with a T2-weighted SPACE sequence at 3 T. For AI a snake algorithm was applied and compared to manual tracing (MT).

Results

AI was feasible in all examined tendons without further correction. AI of both tendons was performed in each participant within 2 min (2 × 37 slices) compared to MT lasting 20 min. MT and AI showed excellent agreement and correlation (R² = 0.99, p < 0.0001). AI provided a reduction of measurement error (0.4 cm³ vs. 0.5 cm³) and coefficient of variation (1% vs. 2%).

Discussion

Compared to MT the AI allows assessment of tendon volumes in highly resolved MRI data in a more accurate and reliable time-saving way. Therefore automated volume detection is seen as a helpful clinical tool for evaluation of small volumetric changes of the Achilles tendon.     

Feasibility of 3.0T pelvic MR imaging in the evaluation of endometriosis

Introduction

Endometriosis represents an important clinical problem in women of reproductive age with high impact on quality of life, work productivity and health care management. The aim of this study is to define the role of 3 T magnetom system MRI in the evaluation of endometriosis.

Materials and methods

Forty-six women, with transvaginal (TV) ultrasound examination positive for endometriosis, with pelvic pain, or infertile underwent an MR 3.0 T examination with the following protocol: T2 weighted FRFSE HR sequences, T2 weighted FRFSE HR CUBE 3D sequences, T1 w FSE sequences, LAVA-flex sequences. Pelvic anatomy, macroscopic endometriosis implants, deep endometriosis implants, fallopian tube involvement, adhesions presence, fluid effusion in Douglas pouch, uterus and kidney pathologies or anomalies associated and sacral nervous routes were considered by two radiologists in consensus. Laparoscopy was considered the gold standard.

Results

MRI imaging diagnosed deep endometriosis in 22/46 patients, endometriomas not associated to deep implants in 9/46 patients, 15/46 patients resulted negative for endometriosis, 11 of 22 patients with deep endometriosis reported ovarian endometriosis cyst. We obtained high percentages of sensibility (96.97%), specificity (100.00%), VPP (100.00%), VPN (92.86%).

Conclusion

Pelvic MRI performed with 3 T system guarantees high spatial and contrast resolution, providing accurate information about endometriosis implants, with a good pre-surgery mapping of the lesions involving both bowels and bladder surface and recto-uterine ligaments.