Ultrasound needle visibility in contrast mode imaging: an in vitro and ex vivo study

PURPOSE: To evaluate needle visibility in ultrasound under contrast mode conditions. MATERIALS AND METHODS: Needle visibility was evaluated for bevel, EchoTip (®) and shaft of 18G Chiba biopsy needle with a 9 MHz linear probe (GE Logiq E9). Insertion angles varied between 30°(steep) and 90°(parallel to the probe surface). The acoustic output varied from 5-28%. 2 different contrast mode presets with either 'Amplitude Modulation' (Penetration) or 'Phase Inversion Harmonics' (High Resolution) were assessed. All other imaging parameters were kept constant. The visibility of bevel, EchoTip (®) and shaft was assessed for grayscale and color-coded images with a 3-point Likert-like scale (not, poorly, well visible) by 2 independent readers. The echogenicity of the needle bevel, EchoTip (®) and shaft was assessed in deciBel (dB) on the color-coded images. RESULTS: With the parallel insertion angle, all needle areas were well visible. With steep insertion the EchoTip (®) was the only visible area. High Resolution was superior to Penetration (p<0.001). The visibility and echogenicity of the needle bevel ( rgrayscale =0.109, p grayscale =0.178; rcolor-coded =0.236, p color-coded =0.266; rdB =0.956, p dB =0.001), EchoTip (®) ( rgrayscale += 0.477, p grayscale += 0.018; rcolor-coded =0.540, p color-coded += 0.006; rdB =0.911, p dB =0.001) and shaft ( rgrayscale =0.124, p grayscale =0.563; rcolor-coded =0.061, p color-coded += 0.775; rdB += 0.926, p dB =0.001) increased with increasing acoustic output. Grayscale images were superior to color-coded images for needle visibility (p=0.004). CONCLUSION: Parallel needle insertion, use of an echogenic tip, adequate choice of presets, increased acoustic output, and dual view of grayscale and color-coded images improve needle visibility in ultrasound under contrast mode conditions

Cinematic rendering - an alternative to volume rendering for 3D computed tomography imaging

Volume rendering (VR) represents today's standard three-dimensional (3-D) image post-processing technique, and often is used to visualize complex anatomical information. Recently, a novel 3-D technique for post-processing of computed tomography (CT) image data has been introduced, which is called cinematic rendering (CR). The objective of this review is to illustrate the image appearance and potential value of CR in comparison with conventional VR in a number of various applications and different anatomical regions. Similar to VR, CR best visualizes high density and high contrast structures such as bones and contrast-enhanced vessels, but at the same time provides a more natural and photo-realistic illumination of the rendered data. Further research will be necessary for determining possible advantages of CR over conventional VR and over two-dimensional (2-D) image post-processing for CT image data

The value of advanced MRI techniques in the assessment of cervical cancer: a review

Abstract Objectives To assess the value of new magnetic resonance imaging (MRI) techniques in cervical cancer. Methods We searched PubMed and MEDLINE and reviewed articles published from 1990 to 2016 to identify studies that used MRI techniques, such as diffusion weighted imaging (DWI), intravoxel incoherent motion (IVIM) and dynamic contrast enhancement (DCE) MRI, to assess parametric invasion, to detect lymph node metastases, tumour subtype and grading, and to detect and predict tumour recurrence. Results Seventy-nine studies were included. The additional use of DWI improved the accuracy and sensitivity of the evaluation of parametrial extension. Most studies reported improved detection of nodal metastases. Functional MRI techniques have the potential to assess tumour subtypes and tumour grade differentiation, and they showed additional value in detecting and predicting treatment response. Limitations included a lack of technical standardisation, which limits reproducibility. Conclusions New advanced MRI techniques allow improved analysis of tumour biology and the tumour microenvironment. They can improve TNM staging and show promise for tumour classification and for assessing the risk of tumour recurrence. They may be helpful for developing optimised and personalised therapy for patients with cervical cancer. Teaching points • Conventional MRI plays a key role in the evaluation of cervical cancer. • DWI improves tumour delineation and detection of nodal metastases in cervical cancer. • Advanced MRI techniques show promise regarding histological grading and subtype differentiation. • Tumour ADC is a potential biomarker for response to treatment

Comparison of medical-grade and calibrated consumer-grade displays for diagnosis of subtle bone fissures

To compare the diagnostic accuracy of medical-grade and calibrated consumer-grade digital displays for the detection of subtle bone fissures. Three experienced radiologists assessed 96 digital radiographs, 40 without and 56 with subtle bone fissures, for the presence or absence of fissures in various bones using one consumer-grade and two medical-grade displays calibrated according to the DICOM-Grayscale Standard Display Function. The reference standard was consensus reading. Subjective image quality was also assessed by the three readers. Statistical analysis was performed using receiver operating characteristic analysis and by calculating the sensitivity, specificity, and Youden's J for each combination of reader and display. Cohen's unweighted kappa was calculated to assess inter-rater agreement. Subjective image quality was compared using the Wilcoxon signed-rank test. No significant differences were found for the assessment of subjective image quality. Diagnostic performance was similar across all readers and displays, with Youden's J ranging from 0.443 to 0.661. The differences were influenced more by the reader than by the display used for the assessment. No significant differences were found between medical-grade and calibrated consumer-grade displays with regard to their diagnostic performance in assessing subtle bone fissures. Calibrated consumer-grade displays may be sufficient for most radiological examinations. aEuro cent Diagnostic performance of calibrated consumer-grade displays is comparable to medical-grade displays. aEuro cent There is no significant difference with regard to subjective image quality. aEuro cent Use of calibrated consumer-grade displays could cut display costs by 60-80%

The Influence of Background Signal Intensity Changes on Cancer Detection in Prostate MRI

OBJECTIVE The objective of this study was to develop a scoring system for background signal intensity changes or prostate homogeneity on prostate MRI and to assess these changes' influence on cancer detection. MATERIALS AND METHODS This institutional review board-approved, HIPAA-compliant, retrospective study included 418 prostate MRI examinations in 385 men who subsequently underwent MRI-guided biopsy. The Likert score for suspicion of cancer assigned by the primary radiologist was extracted from the original report, and histopathologic work-up of the biopsy cores served as the reference standard. Two readers assessed the amount of changes on T2-weighted sequences and assigned a predefined prostate signal-intensity homogeneity score of 1-5 (1 = poor, extensive changes; 5 = excellent, no changes). The sensitivity and specificity of Likert scores for detection of prostate cancer and clinically significant cancer (Gleason score ≥ 3+4) were estimated in and compared between subgroups of patients with different signal-intensity homogeneity scores (≤ 2, 3, and ≥ 4). RESULTS Interreader agreement on signal-intensity homogeneity scores was substantial (κ = 0.783). Sensitivity for prostate cancer detection increased when scores were better (i.e., higher) (reader 1, from 0.41 to 0.71; reader 2, from 0.53 to 0.73; p ≤ 0.007, both readers). In the detection of significant cancer (Gleason score ≥ 3+4), sensitivity also increased with higher signal-intensity scores (reader 1, from 0.50 to 0.82; reader 2, from 0.63 to 0.86; p ≤ 0.028), though specificity decreased significantly for one reader (from 0.67 to 0.38; p = 0.009). CONCLUSION Background signal-intensity changes on T2-weighted images significantly limit prostate cancer detection. The proposed scoring system could improve the standardization of prostate MRI reporting and provide guidance for applying prostate MRI results appropriately in clinical decision-making

Diffusion tensor imaging of lumbar nerve roots: Comparison between fast readout-segmented and selective-excitation acquisitions

OBJECTIVES: The aim of this study was to compare the quality of recently emerged advanced diffusion tensor imaging (DTI) techniques with conventional single-shot echo-planar imaging (EPI) in a functional assessment of lumbar nerve roots. MATERIALS AND METHODS: The institutional review board approved the study including 12 healthy volunteers. Diffusion tensor imaging was performed at 3 T (MAGNETOM Skyra; Siemens Healthcare) with b-values of 0 and 700 s/mm and an isotropic spatial resolution for subsequent multiplanar reformatting. The nerve roots L2 to S1 were imaged in coronal orientation with readout-segmented EPI (rs-DTI) and selective-excitation EPI (sTX-DTI) with an acquisition time of 5 minutes each, and in axial orientation with single-shot EPI (ss-DTI) with an acquisition time of 12 minutes (scan parameters as in recent literature). Two independent readers qualitatively and quantitatively assessed image quality. RESULTS: The interobserver reliability ranged from "substantial" to "almost perfect" for all examined parameter and all 3 sequences (κ = 0.70-0.94). Overall image quality was rated higher, and artifact levels were scored lower for rs-DTI and sTX-DTI than for ss-DTI (P = 0.007-0.027), while fractional anisotropy and signal-to-noise ratio values were similar for all sequences (P ≥ 0.306 and P ≥ 0.100, respectively). Contrast-to-noise ratios were significantly higher for rs-DTI and ss-DTI than for sTX-DTI (P = 0.004-0.013). CONCLUSIONS: Despite shorter acquisition times, rs-DTI and sTX-DTI produced images of higher quality with smaller geometrical distortions than the current standard of reference, ss-DTI. Thus, DTI acquisitions in the coronal plane, requiring fewer slices for full coverage of exiting nerve roots, may allow for functional neurography in scan times suitable for routine clinical practice

MR neurographic orthopantomogram: Ultrashort echo-time imaging of mandibular bone and teeth complemented with high-resolution morphological and functional MR neurography

PURPOSE Panoramical radiographs or cone-beam computed tomography (CT) are the standard-of-care in dental imaging to assess teeth, mandible, and mandibular canal pathologies, but do not allow assessment of the inferior alveolar nerve itself nor of its branches. We propose a new technique for "MR neurographic orthopantomograms" exploiting ultrashort echo-time (UTE) imaging of bone and teeth complemented with high-resolution morphological and functional MR neurography. MATERIALS AND METHODS The Institutional Review Board approved the study in 10 healthy volunteers. Imaging of the subjects mandibles at 3.0T (Magnetom Skyra, Siemens-Healthcare) using a 64-channel head coil with isotropic spatial resolution for subsequent multiplanar reformatting, was performed. Bone images were acquired using a 3D PETRA sequence (TE, 0.07 msec). Morphological nerve imaging was performed using a dedicated 3D PSIF and 3D SPACE STIR sequence. Functional MR neurography was accomplished using a new accelerated diffusion-tensor-imaging (DTI) prototype sequence (2D SMS-accelerated RESOLVE). Qualitative and quantitative image analysis was performed and descriptive statistics are provided. RESULTS Image acquisition and subsequent postprocessing into the MR neurographic orthopantomogram by overlay of morphological and functional images were feasible in all 10 volunteers without artifacts. All mandibular bones and mandibular nerves were assessable and considered normal. Fiber tractography with quantitative evaluation of physiological diffusion properties of mandibular nerves yielded the following mean ± SD values: fractional anisotropy, 0.43 ± 0.07; mean diffusivity (mm(2) /s), 0.0014 ± 0.0002; axial diffusivity, 0.0020 ± 0.0002, and radial diffusivity, 0.0011 ± 0.0001. CONCLUSION The proposed technique of MR neurographic orthopantomogram exploiting UTE imaging complemented with high-resolution morphological and functional MR neurography was feasible and allowed comprehensive assessment of osseous texture and neural microarchitecture in a single examination. J. Magn. Reson. Imaging 2016