Correction to: Is liver lesion characterisation by simplified IVIM DWI also feasible at 3.0 T?

The original version of this article, published on 08 April 2019, unfortunately contained a mistake. The following correction has therefore been made in the original: The caption of Fig. 2 is wrong. The corrected version is given below.

Is liver lesion characterisation by simplified IVIM DWI also feasible at 3.0 T?

OBJECTIVE: To evaluate simplified intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for liver lesion characterisation at 3.0 T and to compare it with 1.5 T. METHODS: 3.0-T DWI data from a respiratory-gated MRI sequence with b = 0, 50, 250, and 800 s/mm2 were analysed in 116 lesions (78 patients) and 27 healthy livers. Apparent diffusion coefficient ADC = ADC(0,800) and IVIM-based parameters D1' = ADC(50,800), D2' = ADC(250,800), f1' = f(0,50,800), f2' = f(0,250,800), D*' = D*(0,50,250,800), ADClow = ADC(0,50), and ADCdiff = ADClow-D2' were calculated voxel-wise and analysed on per-patient basis. Results were compared with those of 173 lesions (110 patients) and 40 healthy livers at 1.5 T. RESULTS: Focal nodular hyperplasias were best discriminated from all other lesions by f1' and haemangiomas by D1' with an area under the curve (AUC) of 0.993 and 1.000, respectively. For discrimination between malignant and benign lesions, ADC was best suited (AUC of 0.968). The combination of D1' and f1' correctly identified more lesions as malignant or benign than the ADC (99.1% vs 88.8%). Discriminatory power for differentiating malignant from benign lesions tended to be higher at 3.0 T than at 1.5 T. CONCLUSION: Simplified IVIM is suitable for lesion characterisation at 3.0 T with a trend of superior diagnostic accuracy for discriminating malignant from benign lesions compared with 1.5 T. KEY POINTS: • Simplified IVIM is also suitable for liver lesion characterisation at 3.0 T. • Excellent accuracy was reached for discriminating malignant from benign lesions. • The acquisition of only three b-values (0, 50, 800 s/mm 2 ) is required.

The role of muscle strength on tendon adaptability in old age.

PURPOSE: The purpose of the study was to determine: (1) the relationship between ankle plantarflexor muscle strength and Achilles tendon (AT) biomechanical properties in older female adults, and (2) whether muscle strength asymmetries between the individually dominant and non-dominant legs in the above subject group were accompanied by inter-limb AT size differences. METHODS: The maximal generated AT force, AT stiffness, AT Young's modulus, and AT cross-sectional area (CSA) along its length were determined for both legs in 30 women (65 ± 7 years) using dynamometry, ultrasonography, and magnetic resonance imaging. RESULTS: No between-leg differences in triceps surae muscle strength were identified between dominant (2798 ± 566 N) and non-dominant limb (2667 ± 512 N). The AT CSA increased gradually in the proximo-distal direction, with no differences between the legs. There was a significant correlation (P < 0.05) of maximal AT force with AT stiffness (r = 0.500) and Young's modulus (r = 0.414), but only a tendency with the mean AT CSA. However, region-specific analysis revealed a significant relationship between maximal AT force and the proximal part of the AT, indicating that this region is more likely to display morphological adaptations following an increase in muscle strength in older adults. CONCLUSIONS: These findings demonstrate that maximal force-generation capabilities play a more important role in the variation of AT stiffness and material properties than in tendon CSA, suggesting that exercise-induced increases in muscle strength in older adults may lead to changes in tendon stiffness foremost due to alterations in material rather than in its size.

Accurate IVIM model-based liver lesion characterisation can be achieved with only three b-value DWI.

OBJECTIVE: The objective of this study was to evaluate a simplified intravoxel incoherent motion (IVIM) approach of diffusion-weighted imaging (DWI) with four b-values for liver lesion characterisation at 1.5 T. METHODS: DWI data from a respiratory-gated MRI sequence with b = 0, 50, 250, 800 s/mm2 were retrospectively analysed in 173 lesions and 40 healthy livers. The apparent diffusion coefficient ADC = ADC(0,800) and IVIM-based parameters D1' = ADC(50,800), D2' =ADC(250,800), f1', f2', D*', ADClow = ADC(0,50), and ADCdiff=ADClow-D2' were calculated voxel-wise without fitting procedures. Differences between lesion groups were investigated. RESULTS: Focal nodular hyperplasias were best discriminated from all other lesions by f1' with an area under the curve (AUC) of 0.989. Haemangiomas were best discriminated by D1' (AUC of 0.994). For discrimination between malignant and benign lesions, ADC(0,800) and D1' were best suited (AUC of 0.915 and 0.858, respectively). Discriminatory power was further increased by using a combination of D1' and f1'. CONCLUSION: IVIM parameters D and f approximated from three b-values provided more discriminatory power between liver lesions than ADC determined from two b-values. The use of b = 0, 50, 800 s/mm2 was superior to that of b = 0, 250, 800 s/mm2. The acquisition of four instead of three b-values has no further benefit for lesion characterisation. KEY POINTS: • Diffusion and perfusion characteristics are assessable with only three b-values. • Association of b = 0, 50, 800 s/mm2is superior to b = 0, 250, 800 s/mm2. • A fourth acquired b-value has no benefit for differential diagnosis. • For liver lesion characterisation, simplified IVIM analysis is superior to ADC determination. • Simplified IVIM approach guarantees numerically stable, voxel-wise results and short acquisition times.

[Benign mesenchymal tumors of the abdomen]. / Benigne mesenchymale Tumoren des Abdomens.

BACKGROUND: Benign mesenchymal tumors of the abdomen are-except for hemangiomas-rare neoplasms that are associated with potentially life-threatening complications. Thus, awareness of the most important entities and knowledge of their imaging characteristics is fundamental for the radiologist. OBJECTIVES: An overview of the most frequent benign abdominal soft tissue tumors and their common imaging features is given. Furthermore, other facts concerning the individual entities that are relevant to radiologic practice are outlined. MATERIALS AND METHODS: A literature search and evaluation of the institutional image database were performed. RESULTS: Hemangiomas, desmoid tumors, lipomas and lipoma variants are presented. Typical characteristics and radiological signs (e. g., iris diaphragm sign, band sign, India ink artifact) are elucidated and illustrated by image examples. CONCLUSION: Despite the lack of distinctive imaging features, there are a few radiological characteristics suggestive for each of the entities that in many cases allow for correct diagnosis. In cases of doubt, biopsy or surgery is necessary to distinguish them from malignancies.

Three-Dimensional Isotropic Fat-Suppressed Proton Density-Weighted MRI at 3 Tesla Using a T/R-Coil Can Replace Multiple Plane Two-Dimensional Sequences in Knee Imaging.

PURPOSE: To evaluate whether a 3 D proton density-weighted fat-suppressed sequence (PDwFS) of the knee is able to replace multiplanar 2D-PDwFS. MATERIALS AND METHODS: 52 patients (26 men, mean age: 41.9 ±â€Š14.5years) underwent magnetic resonance imaging (MRI) of the knee at 3.0 Tesla using a T/R-coil. The imaging protocol included 3 planes of 2D-PDwFS (acquisition time (AT): 6:40 min; voxel sizes: 0.40 - 0.63 × 0.44 - 0.89 × 3mm³) and a 3D-PDwFS (AT: 6:31 min; voxel size: 0.63 × 0.68 × 0.63mm³). Homogeneity of fat suppression (HFS), artifacts, and image sharpness (IS) were evaluated on a 5-point scale (5[excellent] - 1[non-diagnostic]). The sum served as a measure for the overall image quality (OIQ). Contrast ratios (CR) compared to popliteal muscle were calculated for the meniscus (MEN), anterior (ACL) and posterior cruciate ligaments (PCL). In 13 patients who underwent arthroscopic knee surgery, two radiologists evaluated the presence of meniscal, ligamental and cartilage lesions to estimate the sensitivity and specificity of lesion detection. RESULTS: The CR was higher in the ACL, PCL and MEN in 3D- PDwFS compared to 2D-PDwFS (p < 0.01 for ACL and PCL; p = 0.07 for MEN). Compared to 2 D images, the OIQ was rated higher in 3D-PDwFS images (p < 0.01) due to fewer artifacts and HFS despite the lower IS (p < 0.01). The sensitivity and specificity of lesion detection in 3D- and 2D-PDwFS were similar. CONCLUSION: Compared to standard multiplanar 2D-PDwFS knee imaging, isotropic high spatial resolution 3D-PDwFS of the knee at 3.0 T can be acquired with high image quality in a reasonable scan time. Multiplanar reformations in arbitrary planes may serve as an additional benefit of 3D-PDwFS. KEY POINTS: • 3D-PDwFS of the knee is acquired with high image quality• 3D-PDwFS can be achieved in only one measurement with a reasonable scan time• 3D-PDwFS with the advantage of multiplanar reformation may replace 2D-PD-weighted knee MRI Citation Format: • Homsi R, Gieseke J, Luetkens JA et al. Three-Dimensional Isotropic Fat-Suppressed Proton Density-Weighted MRI at 3 Tesla Using a T/R-Coil Can Replace Multiple Plane Two-Dimensional Sequences in Knee Imaging. Fortschr Röntgenstr 2016; 188: 949 - 956.

Intravoxel incoherent motion model-based liver lesion characterisation from three b-value diffusion-weighted MRI.

OBJECTIVE: To evaluate intravoxel incoherent motion (IVIM) model-based liver lesion characterisation from three b-value diffusion-weighted imaging (DWI). METHODS: The 1.5-T DWI data from a respiratory gated spin-echo echo-planar magnetic resonance imaging sequence (b = 0, 50, 800 s/mm(2)) were retrospectively analysed in 38 patients with different liver lesions. Conventional apparent diffusion coefficient ADC = ADC(0,800) as well as IVIM-based parameters D' = ADC(50,800), ADC_low = ADC(0,50), and f' were calculated voxel-wise. Sixty-one regions of interest in hepatocellular carcinomas (HCCs, n = 24), haemangiomas (HEMs, n = 11), focal nodular hyperplasias (FNHs, n = 11), and healthy liver tissue (REFs, n = 15) were analysed. Group differences were investigated using Student's t-test and receiver-operating characteristic (ROC) analysis. RESULTS: Mean values ± standard deviations of ADC, D', ADC_low (in 10(-5) mm(2)/s), and f' (in %) for REFs/FNHs/HEMs/HCCs were 130 ± 11/143 ± 27/168 ± 16/113 ± 25, 104 ± 12/123 ± 25/162 ± 18/102 ± 23, 518 ± 66/437 ± 97/268 ± 69/283 ± 120, and 18 ± 3/14 ± 4/6 ± 3/9 ± 5, respectively. Differences between lesions and REFs were more significant for IVIM-based parameters than for conventional ADC. ROC analysis showed the best discriminability between HCCs and FNHs for ADC_low and f' and between HEMs and FNHs or HCCs for D'. CONCLUSION: Three instead of two b-value DWI enables a numerically stable and voxel-wise IVIM-based analysis for improved liver lesion characterisation with tolerable acquisition time. KEY POINTS: • Quantitative analysis of diffusion-weighted MRI helps liver lesion characterisation. • Analysis of intravoxel incoherent motion is superior to apparent diffusion coefficient determination. • Only three b-values enable separation of diffusion and microcirculation effects. • The method presented is numerically stable, with voxel-wise results and short acquisition times.

Noninvasive evaluation of cerebral arteriovenous malformations by 4D-MRA for preoperative planning and postoperative follow-up in 56 patients: comparison with DSA and intraoperative findings.

BACKGROUND AND PURPOSE: 4D-MRA is a promising technique in the diagnosis and follow-up of cAVMs. The purpose of this study was to compare 4D-MRA in the pre- and postoperative evaluation of cAVMs with DSA or intraoperative findings as the standards of reference regarding qualitative and quantitative parameters. MATERIALS AND METHODS: Fifty-six consecutive patients with cAVMs (30 women) underwent both 4D-MRA and DSA. Preoperative 4D-MRA was excluded from analysis in 1 patient (movement artifacts). Twenty-five patients underwent surgery on cAVMs and underwent both imaging modalities pre- and postoperatively. 4D-MRA was performed with either 0.5-mol/L gadolinium-diethylene-triamine pentaacetic acid (group 1: voxel size, 1.1 × 1.1 × 1.4 mm(3); 608 ms/dynamic frame; 19 patients) or 1.0-mol/L gadobutrol (group 2: voxel size, 1.1 × 1.1 × 1.1 mm(3); 572 ms/dynamic frame; additional alternating view sharing; 37 patients). Two readers independently reviewed 4D-MRA and DSA regarding the Spetzler-Martin classification, arterial feeders, and postoperative residual filling. Vessel sharpness, vessel diameter, and VBC of 4D-MRA were quantified. RESULTS: Preoperative Spetzler-Martin classification 4D-MRA and DSA ratings matched in 55/55 patients (Spetzler-Martin grades: I, 12; II, 22; III, 15; IV, 5; V, 1), and 93/100 arterial feeders were correctly identified by preoperative 4D-MRA (7 additional arterial feeders identified by DSA only: group 1, 3/19; group 2, 4/36). Postoperative 4D-MRA and DSA matched in 25/25 patients (residual filling, 1/25). Vessel sharpness and diameters did not differ substantially between the 2 groups. VBC was significantly higher in group 2 (P < .005). CONCLUSIONS: 4D-MRA is a reliable tool that allows predicting Spetzler-Martin classification and postoperative residual filling; it hence allows substituting DSA in the pre- and postoperative evaluation of patients with cerebral AVMs.

A gene for hypotrichosis simplex of the scalp maps to chromosome 6p21.3.

Hypotrichosis simplex of the scalp (HSS) is an autosomal dominant form of isolated alopecia causing almost complete loss of scalp hair, with onset in childhood. After exclusion of candidate regions previously associated with hair-loss disorders, we performed a genomewide linkage analysis in two Danish families and localized the gene to chromosome 6p21.3. This was confirmed in a Spanish family, with a total LOD score of 11.97 for marker D6S1701 in all families. The combined haplotype data identify a critical interval of 14.9 cM between markers D6S276 and D6S1607. Localization of the locus for HSS to 6p21.3 is a first step toward identification of the gene. The gene will give important insights into the molecular and cellular basis of hair growth on the scalp.