Evaluation of liver iron overload with R2* relaxometry with versus without fat suppression: both are clinically accurate but there are differences.

OBJECTIVES: To assess clinically relevant difference in hepatic iron quantification using R2* relaxometry with (FS) and without (non-FS) fat saturation for the evaluation of patients with suspected hepatic iron overload. METHODS: We prospectively enrolled 134 patients who underwent 1.5-T MRI R2* relaxometry with FS and non-FS gradient echo sequences (12 echoes, initial TE = 0.99 ms). Proton density fat fraction for the quantification of steatosis was assessed. Linear regression analyses and Bland-Altman plots including Lin's concordance correlation coefficient were performed for correlation of FS R2* with non-FS R2*. Patients were grouped into 4 severity classes of iron overload (EASL based), and agreement was evaluated by contingency tables and the proportion of overall agreement. RESULTS: A total of 41.8% of patients showed hepatic iron overload; 67.9% had concomitant steatosis; and 58.2% revealed no iron overload of whom 60.3% had steatosis. The mean R2* value for all FS data was 102.86 1/s, for non-FS 108.16 1/s. Linear regression resulted in an R-squared value of 0.99 (p < 0.001); Bland-Altman plot showed a mean R2* difference of 5.26 1/s (SD 17.82). The concordance correlation coefficient was only slightly lower for patients with steatosis compared with non-steatosis (0.988 vs. 0.993). The overall agreement between FS and non-FS R2* measurements was 94.8% using either method to classify patients according to severity of iron storage. No correlation between R2* and proton density fat fraction was found for both methods. CONCLUSION: R2* relaxometry showed an excellent overall agreement between FS and non-FS acquisition. Both variants can therefore be used in daily routine. However, clinically relevant differences might result when switching between the two methods or during patient follow-up, when fat content changes over time. We therefore recommend choosing a method and keeping it straight in the context of follow-up examinations. KEY POINTS: • Both variants of R2* relaxometry (FS and non-FS) may be used in daily routine. • Clinically relevant differences might result when switching between the two methods or during patient follow-up, when fat content changes over time. • It seems advisable choosing one method and keeping it straight in the context of follow-up examinations.

Readout-Segmented Echo-Planar DWI for the Detection of Cholesteatomas: Correlation with Surgical Validation.

BACKGROUND AND PURPOSE: MR imaging has become an important tool for the detection of cholesteatomas of the middle ear. Various diffusion-weighted imaging sequences are available and have shown promising results. This study aimed to evaluate readout-segmented echo-planar DWI for the detection of cholesteatoma and compare the results with surgical validation. MATERIALS AND METHODS: Fifty patients with chronic otitis media (24 females and 26 males; range, 12-76 years of age; mean age, 41 years) who underwent MR imaging before an operation of the middle ear (1-169 days) were included. The MR imaging protocol consisted of axial and coronal readout-segmented echo-planar DWI with b-values of 0 and 1000 s/mm2 and 3-mm slice thickness. The readout-segmented echo-planar diffusion-weighted images were fused with standard T2-weighted sequences for better anatomic assignment. The results of the MR imaging evaluation were correlated with the results from the operation. RESULTS: Readout-segmented echo-planar DWI detected 22 of the 25 cases of surgically proved cholesteatoma. It has an accuracy of 92% (95% confidence interval, 80.8%-97.8%), a sensitivity of 88%, a specificity of 96%, a positive predictive value of 96%, and a negative predictive value of 89%. In 1 case, a positive finding for cholesteatoma with readout-segmented echo-planar DWI could not be proved by histology, and in 3 cases, histology yielded a cholesteatoma that was not detected with MR imaging. CONCLUSIONS: Readout-segmented echo-planar DWI is a promising and reliable MR imaging sequence for the detection and exclusion of cholesteatoma.

Does gadoxetate disodium affect MRE measurements in the delayed hepatobiliary phase?

OBJECTIVES: To assess if the administration of gadoxetate disodium (Gd-EOB-DTPA) significantly affects hepatic magnetic resonance elastography (MRE) measurements in the delayed hepatobiliary phase (DHBP). METHODS: A total of 47 patients (15 females, 32 males; age range 23-78 years, mean 54.28 years) were assigned to standard hepatic magnetic resonance imaging (MRI) with application of Gd-EOB-DTPA and hepatic MRE. MRE was performed before injection of Gd-EOB-DTPA and after 40-50 min in the DHBP. Liver stiffness values were obtained before and after contrast media application and differences between pre- and post-Gd-EOB-DTPA values were evaluated using a Bland-Altman plot and the Mann-Whitney-Wilcoxon test. In addition, the data were compared with regard to the resulting fibrosis classification. RESULTS: Mean hepatic stiffness for pre-Gd-EOB-DTPA measurements was 4.01 kPa and post-Gd-EOB-DTPA measurements yielded 3.95 kPa. We found a highly significant individual correlation between pre- and post-Gd-EOB-DTPA stiffness values (Pearson correlation coefficient of r = 0.95 (p < 0.001) with no significant difference between the two measurements (p =0.49)). Bland-Altman plot did not show a systematic effect for the difference between pre- and post-stiffness measurements (mean difference: 0.06 kPa, SD 0.81). Regarding the classification of fibrosis stages, the overall agreement was 87.23% and the intraclass correlation coefficient was 96.4%, indicating excellent agreement. CONCLUSIONS: Administration of Gd-EOB-DTPA does not significantly influence MRE stiffness measurements of the liver in the DHBP. Therefore, MRE can be performed in the DHBP. KEY POINTS: • MRE of the liver can reliably be performed in the delayed hepatobiliary phase. • Gd-EOB-DTPA does not significantly influence MRE stiffness measurements of the liver. • MRE performed in the delayed hepatobiliary-phase is reasonable in patients with reduced liver function.

[Muscular injuries of athletes : Importance of ultrasound]. / Muskelverletzungen des Sportlers : Stellenwert des Ultraschalls.

CLINICAL/METHODICAL ISSUE: Muscular injuries represent the most common musculoskeletal lesions. Especially in professional athletes an imaging clarification is essential in order to define the exact location of the lesion, the affected muscles, the extent and degree of the injury as well as to define possible concomitant complications. The best possible therapy can be initiated and a necessary rest period for a low risk resumption of sporting activity can be individually specified. STANDARD RADIOLOGICAL METHODS/METHODICAL INNOVATIONS: Due to technical improvements, for example mobile devices and thus increased rapid availability as well as relative cost-effectiveness compared to other modalities, the imaging evaluation of muscle injury would nowadays be unthinkable without ultrasound. PERFORMANCE: The article discusses general prerequisites for the performance of muscle ultrasound as well as a standardized examination algorithm of muscle injuries beginning with general and leading to special tips and tricks. ACHIEVEMENTS/PRACTICAL RECOMMENDATIONS: Despite the known investigator dependence, ultrasound enables a reliable and unerring imaging clarification of muscle injuries. For this reason, ultrasound should be considered as the first-line diagnostic imaging modality when dealing with muscle trauma.

R2*-relaxometry of the pancreas in patients with human hemochromatosis protein associated hereditary hemochromatosis.

PURPOSE: To evaluate pancreatic iron in patients with human hemochromatosis protein associated hereditary hemochromatosis (HHC) using R2* relaxometry. MATERIALS AND METHODS: 81 patients (58 male, 23 female; median age 49.5, range 10-81 years) with HHC were retrospectively studied. All underwent 1.5T magnetic resonance imaging (MRI) of the abdomen. A fat-saturated multi-gradient echo sequence with 12 echoes (TR=200ms; TE-initial 0.99ms; Delta-TE 1.41ms; 12 echoes; flip-angle: 20°) was used for the R2* quantification of the liver and the pancreas. Parameter maps were analyzed using regions of interest (3 in the liver and 2 in the pancreas) and R2* values were correlated. RESULTS: 59/81 patients had a liver R2*≥70 1/s of which 10/59 patients had a pancreas R2*≥50 1/s. No patient presented with a liver R2*<70 1/s and pancreas R2*≥50 1/s. All patients with pancreas R2* values≥50 1/s had liver R2* values≥70 1/s. ROC analysis resulted in a threshold of 209.4 1/s for liver R2* values to identify HFE positive patients with pancreas R2* values≥50 1/s with a median specificity of 78.87% and a median sensitivity of 90%. CONCLUSION: In patients with HHC R2* relaxometry of the pancreas should be performed when liver iron overload is present and can be omitted in cases with no sign of hepatic iron.

[Ultrasound-guided interventions on the peripheral nervous system]. / Ultraschallgesteuerte Interventionen am peripheren Nervensystem.

CLINICAL/METHODICAL ISSUE: Up to the advent of high-resolution ultrasound, interventions on the peripheral nervous system, including local anesthesia and pain treatment were performed without visual guidance, which in some cases led to treatment failure or local tissue and nerve damage. METHODICAL INNOVATIONS: Progress in the field of ultrasound has enabled the functional visualization, anesthesia and anti-inflammatory or neurolytic treatment of many peripheral nerves, such as the brachial plexus, nerves of the upper and lower extremities and various nerves of the trunk. Contrast medium-guided biopsies have also become feasible. ACHIEVEMENTS: This article discusses the general prerequisites for such interventions and details the visualization and the interventional algorithms for interventions on the brachial plexus, on large nerves often affected by compression neuropathies, such as the median, ulnar, sciatic and femoral nerves and small nerves, such as the lateral cutaneous nerves of the thigh. Furthermore, contrast medium-aided biopsies of intraneural and perineural masses are discussed. Finally, the treatment of stump neuromas via phenol instillation is described. PRACTICAL RECOMMENDATIONS: Innovations in high-resolution ultrasound allow the reliable and safe diagnosis and treatment of various pathologies of the peripheral nervous system with few side effects. Compared to older methods, which did not use visual guidance ultrasound provides higher success rates and lower adverse event rates in many instances.

The Ulnar Nerve After Surgical Transposition: Can Sonography Define the Reason of Persisting Neuropathy?

PURPOSE: Ulnar nerve neuropathy is mainly caused by compression at the level of the cubital tunnel. Two main approaches are currently known for the surgical treatment of this condition: decompression of the nerve in its usual position or transposition to the ulnar flexor side. This study was performed to define the usefulness of ultrasound in patients with persisting symptoms after ulnar nerve transposition. MATERIALS AND METHODS: We present the data of 8 subjects with persisting symptoms after nerve transposition due to compressive neuropathy. The cross-section areas (CSA) and texture changes were recorded. Each ulnar nerve was divided into 6 segments - 3 segments at the proximal pass and 3 segments at the distal pass through the subcutaneous fascia. RESULTS: Texture changes were recorded in 4.6 (76.7 %)  ±â€Š1.2 and outer nerve sheath blurring in mean 4.1 (68.3 %)  ±â€Š1.1 of the segments. Caliber changes were found in the course of the nerve based on the 6 segments: A mean CSA of 7.45  mm²â€Š ±  2.24 was found proximal to the upper fascial passage (PUF), a mean CSA of 11.96  mm²  ±  3.61  at the upper fascial passage (UF), a mean CSA of 11.49  mm²â€Š ±â€Š 8.16 distal to the upper fascial passage (DUF), a mean CSA of 10.84  mm²â€Š ±  4.73 proximal to the lower fascial passage (PLF), a mean CSA of 12.12  mm²â€Š ±â€Š 5  at the lower fascial passage (LF), and a mean CSA of 7.89  mm²  ±  3.42 distal to the lower fascial passage (DLF). All transposed nerves presented relevant kinks at the UF, 6 nerves presented relevant kinks at the LF. CONCLUSION: In cases of secondary ulnar neuropathy after nerve transposition, ultrasound can reliably assess the actual "situation" of the nerve and thus at least ease the decision for secondary surgery.

Transperineal ultrasonography as a complementary diagnostic tool in identifying acute perianal sepsis.

BACKGROUND: Successful anal fistula care in complex cases can be assisted by specialized imaging which accurately defines the site of the internal fistula opening and the fistula type. There are currently limited data concerning the clinical indications for and accuracy of transperineal ultrasound (TP-US) in acute perianal sepsis. The aims of this study were to compare the anatomical interpretation of TP-US images with magnetic resonance imaging (MRI) and surgical findings in an unselected patient cohort presenting with acute perianal sepsis. METHODS: Sixty-seven consecutive patients with acute anorectal sepsis referred from the surgical department were examined using TP-US and Gadolinium-enhanced MRI with both examiners blinded to the surgical results. Fistulae were categorized by the Parks' classification of fistula type. RESULTS: Thirty-six abscesses were detected by MRI, 38 by TP-US and 30 by surgical examination. Operatively discordant cases showed only ischiorectal panniculitis. TP-US was more accurate in the diagnosis of superficial sepsis and MRI in the diagnosis of deep-seated perirectal infection. TP-US and MRI show concordance with operative findings in fistula diagnosis with a tendency for TP-US to overdiagnose trans-sphincteric fistulae and MRI to over diagnose extra-sphincteric fistulae. Comparison of TP-US with MRI showed good agreement for perianal abscess diagnosis (τ = 0.82) and for fistula diagnosis (τ = 0.68). For fistulae, TP-US showed moderate agreement with surgery (τ = 0.43) with only fair agreement between MRI and surgery (τ = 0.29). CONCLUSIONS: Transperineal ultrasound complements other imaging modalities in the anatomical diagnosis of acute perianal abscesses and fistulae. It has specific advantages over other techniques and is accurate in the detection of superficially located perirectal sepsis showing concordance with MRI and surgical findings.

Thickened hyperechoic outer epineurium, a sonographic sign suggesting snapping ulnar nerve syndrome?

PURPOSE: Snapping ulnar nerve syndrome (dislocation of the ulnar nerve over the medial epicondyle) is one of many causes of ulnar neuropathy at the elbow. This preliminary study was performed to search for sonographic signs suggesting the presence of this condition. METHODS AND MATERIALS: We retrospectively investigated 11 patients with snapping ulnar nerve syndrome (SNAP) in comparison with an age-matched group of 20 patients with idiopathic cubital tunnel syndrome (SNU). Patients were grouped according to the presence of paretic or merely sensory deficits. Nerve cross section area (CSA) and thickness of outer epineurium (ET) was measured and correlated with neurological findings. Statistical differences were evaluated with the Mann-Whitney U-Test. RESULTS: 5 SNAP (10 SNU) patients had sensory symptoms only, 6 SNAP (10 SNU) patients had paretic deficits. CSA in sensory SNU was 0.14 cm(2), in paretic SNU 0.19 cm(2), in sensory SNAP 0.15 cm(2) and in paretic SNAP 0.14 cm(2). ET in sensory SNU was 0.85 mm, 0.8 mm in paretic SNU, 1.05 mm in sensory SNAP and 1.1 in paretic SNAP. Differences in CSA were not significant depending on symptoms or group, differences in ET were not significant depending on symptoms but on group (SNAP versus SNU) at α = 0.05. CONCLUSION: A thickened, hyperechoic outer epineurium in a patient with ulnar neuropathy at the elbow might be a statistically significant differential feature of snapping ulnar nerve syndrome and should be involved in a further functional sonographic evaluation during flexion/extension of the elbow.

Punched nerve syndrome: ultrasonographic appearance of functional vascular nerve impairment.

PURPOSE: The mechanical impact of a neighboring vessel on a "punched" nerve segment is thought to be one possible cause of compression neuropathy but has not been proven definitively. We report on 9 subjects with unclear clinical mononeuropathies in whom we could clearly define peripheral nerve impairment by such vessels on real-time high-resolution ultrasound (HRUS). MATERIALS AND METHODS: Nine subjects with unclear mononeuropathy based on clinical neurological examination were referred to our department for HRUS assessment. The shape, inner and outer echotexture, size and diameter, and overall integrity of these nerves were assessed including an exact analysis of the surrounding soft tissues to search for potentially extraneural pathology. This included duplex imaging to identify even tiny atypical vascular structures. RESULTS: In all patients duplex HRUS showed the pulsatile and "punching" character of the relevant vessels and the direct mechanical impact of these vessel. The involved nerve segments appeared enlarged with a hypoechoic change of echotexture including at least partial masking of their inner fascicular texture. CONCLUSION: Although rare, a "punching" vessel can be the cause of a compression neuropathy. Therefore, duplex HRUS must be included in every HRUS examination of patients with otherwise unclear mononeuropathy.