Comparison of conventional sonography, real-time compound sonography, tissue harmonic sonography, and tissue harmonic compound sonography of abdominal and pelvic lesions

OBJECTIVE: The purpose of this study was to compare conventional sonography, real-time spatial compound sonography, tissue harmonic sonography, and tissue harmonic sonography merged with compound sonography for overall image quality, lesion conspicuity, and elimination of artifacts. SUBJECTS AND METHODS. In this study, 150 lesions in 122 randomly selected patients with various abdominal and pelvic lesions were evaluated. For each lesion, sonograms were obtained with four techniques: conventional sonography, real-time spatial compound sonography, tissue harmonic sonography, and tissue harmonic compound sonography. All images were reviewed and graded independently by two observers for overall image quality, lesion conspicuity, and elimination of artifacts. RESULTS: Statistical analysis showed that for overall image quality, lesion conspicuity, and elimination of artifacts, tissue harmonic compound sonography was significantly superior to all of the other techniques; real-time spatial compound sonography was better than tissue harmonic sonography; and conventional sonography was the least valuable of all (p < 0.001). When data were analyzed separately according to lesion types, tissue harmonic compound sonography was significantly superior for revealing stone diseases, liver cysts, gallbladder polyps, and uterine myomas. For the remainder of lesion groups, spatial compounding was superior to tissue harmonic sonography for all aspects of evaluation, and conventional sonography was the least valuable (p < 0.05). CONCLUSION: In abdominal and pelvic scanning, tissue harmonic compound sonography provides the best overall image quality, best lesion conspicuity, and least artifacts of all the evaluated imaging modes. Spatial compound sonography is better than tissue harmonic sonography for the evaluation of lesions in general, despite some differences among lesion groups.     

The benefits of comparing conventional sonography, real-time spatial compound sonography, tissue harmonic sonography, and tissue harmonic compound sonography of hepatic lesions

This study aimed to compare conventional sonography, tissue harmonic imaging (THI), spatial compound sonography (SONOCT), and SONOCT+THI for overall image quality, lesion conspicuity, and elimination of artifacts of hepatic lesions. Forty-five patients were randomly selected, and 51 different hepatic lesions were scanned using each of the four techniques. The combined images of SONOCT+THI exhibited the best image quality for solid and cystic lesions, while conventional images were the worst for most hepatic lesions (P<.001). SONOCT was the best for fatty liver.     

Diagnostic accuracy of phase-inversion tissue harmonic imaging versus fundamental B-mode sonography in the evaluation of focal lesions of the kidney

OBJECTIVE: We compared phase-inversion tissue harmonic imaging with fundamental B-mode sonography in the evaluation of focal lesions of the kidney. SUBJECTS AND METHODS: For our prospective study, 114 patients underwent sonography of the kidneys in both modes, fundamental B-mode sonography and phase-inversion tissue harmonic imaging, in a randomly chosen scanning order. Imaging parameters were standardized. Sonographic diagnoses were made under real-time conditions by the examining radiologist. All sonographic diagnoses were compared with a diagnostic reference modality: contrast-enhanced CT, contrast-enhanced MR imaging, or histopathology. Three radiologists different from the examiners evaluated overall image quality, lesion conspicuity, and fluid-solid differentiation for both modalities using hard-copy images. RESULTS: In 70 patients, fundamental B-mode sonography as the first technique depicted 73 of 111 lesions 10 mm or larger and enabled 71 lesions to be correctly characterized (sensitivity, 65.8%; accuracy, 64.0%). As the first mode, phase-inversion tissue harmonic imaging depicted 57 of 65 focal lesions and enabled 54 lesions to be accurately classified in 44 patients (sensitivity, 87.7%; accuracy, 83.1%). The differences in sensitivity and accuracy were statistically significant (95% confidence interval). For overall image quality, lesion conspicuity, and fluid-solid differentiation phase-inversion harmonic imaging was superior to fundamental B-mode sonography (p < 0.0001). CONCLUSION: Phase-inversion tissue harmonic imaging is superior to fundamental B-mode sonography in the sonography of focal kidney lesions because phase-inversion tissue harmonic imaging has better overall image quality, lesion conspicuity, and fluid-solid differentiation. In six cases, phase-inversion tissue harmonic imaging added crucial diagnostic information that changed patient management.     

Four-dimensional volume contrast ultrasound imaging of the gallbladder compared with tissue harmonic imaging: preliminary experience

Comparison of volume contrast US imaging with tissue harmonic imaging for the evaluation of gallbladder lesions and determination of the adequate slice thickness in volume contrast US imaging were performed. Forty-one patients who had gallbladder lesions (polyps in 26, stones in 12, and sludge in 3) were enrolled in our study. A Voluson 730 Expert US scanner was used throughout. Volume contrast US imaging with slice thicknesses of 3, 5, 10 and 15 mm and tissue harmonic imaging of the gallbladder were obtained. Two abdominal radiologists reviewed the masked images and graded by consensus these images using a five-point scale [from grade 1, (best), to grade 5, (worst)], based on the sharpness of the anterior gallbladder wall, internal artifact, lesion conspicuity and acoustic shadowing from stone. Volume contrast US imaging with thin slice thicknesses (3 or 5 mm) was judged superior to both tissue harmonic imaging and with thick slice thicknesses (10 or 15 mm), with respect to the sharpness of the anterior wall and lesion conspicuity (P<0.001). In terms of internal artifact, volume contrast imaging with thin slice thicknesses was significantly superior to both tissue harmonic imaging and volume contrast imaging with a 15 mm thickness (P<0.001) and was judged to be marginally better than with a 10 mm thickness (p>0.01). With regard to acoustic shadowing, volume contrast imaging with thin slice thicknesses was also significantly better than with thick slice thicknesses (P<0.01), and it was also marginally better than tissue harmonic imaging (P>0.01). Volume contrast US imaging with thin slice thicknesses provides a better image quality with fewer artifacts than three other types of images for the evaluation of gallbladder diseases.     

T2-weighted breath-hold MRI of the liver at 1.0 T: Comparison of turbo spin-echo and HASTE sequences with and without fat suppression

To compare the clinical usefulness of T2-weighted breath-hold sequences for imaging the liver, 33 patients with 97 focal hepatic lesions were studied with a 1.0-T scanner by using T2-weighted breath-hold turbo spin-echo (SE) sequences and T2-weighted breath-hold half-Fourier single-shot turbo SE (HASTE) sequences with and without fat suppression. Images were quantitatively analyzed for liver signal-to-noise ratio (SNR) and lesion-to-liver contrast-to-noise ratios (CNR). Qualitative analysis was performed for lesion conspicuity, motion artifacts, and anatomic sharpness of extrahepatic structures. Breath-hold turbo SE imaging with fat suppression showed the highest CNR for cystic lesions and the best lesion conspicuity for cystic and solid lesions among the four sequences. For solid lesions, there was no significant difference of lesion-to-liver CNR between them. HASTE sequence was superior to turbo SE sequences in terms of motion artifacts; however, the usefulness for evaluating focal hepatic lesions was limited compared with turbo SE sequence with fat suppression. Addition of fat suppression was not helpful for HASTE imaging because of decreased lesion conspicuity and extrahepatic details without the advantage of reducing motion artifacts. This study suggests that turbo SE sequence with fat suppression is most useful for breath-hold T2-weighted liver imaging at 1.0 T. Addition of imaging without fat suppression can be considered for evaluating extrahepatic structures. HASTE sequence may have a role for imaging uncooperative patients due to absence of motion artifacts.     

Combination of tissue harmonic sonography, real-time spatial compound sonography and adaptive image processing technique for the detection of carotid plaques and intima-medial thickness

Background and purpose

Conventional sonography (CS) had many unwanted artifacts, which obscured the carotid artery lesions. We try to explore whether the combination of tissue harmonic imaging (THI), real-time spatial compound sonography (SCS), and adaptive image processing (AIP) techniques (CTX) could be a better way to reduce the artifacts in the carotid artery and enhance the visualization of its plaques and intima-medial thickness (IMT) than CS.

Methods

Eighty-three patients who harbored IMT (73) and carotid plaques (19) with variable degrees of stenosis underwent scanning for which five different ultrasound techniques were performed for overall image quality, lesion conspicuity, and elimination of artifacts. Two observers, who were blinded to the imaging techniques, graded the different images. A Friedman test was used for multiple statistical comparisons between the five techniques. To make paired comparisons between different imaging modes, Wilcoxon's signed-rank test was used.

Results

The mean Kappa score for the two independent observers was 0.812 (standard error, 0.021), and reflected moderate-to-high interobserver agreement. Combining SCS + THI + AIP (CTX) provided the best for overall image quality, lesion conspicuity, and elimination of undesired artifacts of carotid plaques whereas CS produced the worst quality (p < 0.001). There were significant differences among the five techniques (p < 0.001); however, there were no differences between SCS and THI on either image quality (p = 0.417), lesion conspicuity (p = 0.594), or elimination of artifact (p = 0.064).

Conclusions

The combined technique of SCS, THI, and AIP may represent the optimal ultrasonic technique for the evaluation of the IMT and carotid plaque echomorphology.     

Sonographic Evaluation of Breast Nodules: Comparison of Conventional, Real-Time Compound, and Pulse-Inversion Harmonic Images

Objective

To compare the use of conventional, real-time compound, and pulse-inversion harmonic imaging in the evaluation of breast nodules.

Materials and Methods

Fifty-two breast nodules were included in this study, conducted between May and December 2000, in which conventional, real-time compound, and pulse-inversion harmonic images were obtained in the same plane. Three radiologists, each blinded to the interpretations of the other two, evaluated the findings, characterizing the lesions and ranking the three techniques from grade 1, the worst, to grade 3, the best. Lesion conspicuity was assessed, and lesions were also characterized in terms of their margin, clarity of internal echotexture, and clarity of posterior echo pattern. The three techniques were compared using Friedman''s test, and interobserver agreement in image interpretation was assessed by means of the intraclass correlation coefficient.

Results

With regard to lesion conspicuity, margin, and internal echotexture of the nodules, real-time compound imaging was the best technique (p < 0.05); in terms of posterior echo pattern, the best was pulse-inversion harmonic imaging (p < 0.05). Real-time compound and pulse inversion harmonic imaging were better than conventional sonography in all evaluative aspects. Interobserver agreement was greater than moderate.

Conclusion

Real-time compound and pulse-inversion harmonic imaging procedures are superior to conventional sonography in terms of both lesion conspicuity and the further characterization of breast nodules. Real-time compound imaging is the best technique for evaluation of the margin and internal echotexture of nodules, while pulse-inversion harmonic imaging is very effective for the evaluation of the posterior echo patterns.     

Quantitative dynamic contrast-enhanced sonography of hepatic tumors

Liver tumors are defined using quantitative dynamic contrast-enhanced ultrasound compared to histological diagnosis, respectively, long-term follow-ups. Forty-two focal liver lesions in 39 patients were examined by contrast harmonic imaging over a period of 2 min after bolus injection of 10-ml galactose-based contrast agent. Vascular enhancement was quantified by using a dedicated software that allowed us to place representative regions of interest (ROI) in the center of the lesion, in the complete lesion, in regular liver parenchyma and in representative liver vessels (artery, vein and portal vein). Peak enhancement was judged to be either in the arterial, portal venous or in the late phase of liver perfusion. The lesion was described as hypovascular, isovascular and hypervascular compared to liver parenchyma. Contrast uptake was described as centrifugal or centripetal and peripheral or homogenous, respectively. Characterization of the lesions was performed unenhanced and after contrast by four independent specialists unaware of histology. Diagnosis of malignancy was evaluated by using a receiver operating characteristic (ROC) analysis, also overall accuracy, average sensitivity, specificity and negative and positive predictive values were calculated. Interobserver agreement was defined by the Kappa statistics. Histologic examination revealed 29 malignant [hepatocellular carcinoma (HCC), n=11; cholangiocellular carcinoma (CCC), n=1; lymphoma, n=1; metastases, n=16)] and 7 benign [hemangioma, n=1; focal nodular hyperplasia (FNH), n=4, adenoma, n=2)] lesions. Six benign lesions (hemangioma n=1; FNH n=5) were proved by long-term follow-up. ROC analysis regarding the diagnosis of malignancy showed values from 0.43 to 0.62 (mean 0.57) before and from 0.70 to 0.80 (mean 0.75) after contrast agent, respectively. The average values for sensitivity, specificity, accuracy and negative and positive predictive values were 66, 26, 62, 45 and 73% unenhanced and 83, 49, 73, 65 and 82% after contrast, respectively. The interobserver agreement was 0.54 and 0.65 for unenhanced and enhanced examinations, respectively. Quantitative dynamic contrast-enhanced sonography improves the diagnosis of malignancy in liver lesions.     

T1-weighted spoiled gradient-echo MR imaging of focal hepatic lesion: comparison of in-phase vs opposed-phase pulse sequence

The goal of our prospective study was to compare quantitatively and qualitatively in-phase and opposed-phase T1-weighted breath-hold spoiled gradient-recalled-echo (GRE) MR imaging technique for imaging focal hepatic lesion. Thirty-eight patients with 53 focal hepatic lesions had in-phase (TR = 12.3 ms, TE = 4.2 ms) and opposed-phase (TR = 10.1 ms, TE = 1.9 ms) GRE (flip angle = 30°, bandwidth ± 32 kHz, matrix size 256 × 128, one signal average) MR imaging at 1.5 T. Images were analyzed quantitatively by measuring the lesion-to-liver contrast and for lesion detection. In addition, images were reviewed qualitatively for lesion conspicuity. Quantitatively, lesion-to-liver contrast obtained with in-phase (3.22 ± 1.86) and opposed-phase pulse sequence (3.72 ± 2.32) were not statistically different (Student's t-test). No difference in sensitivity was found between in-phase and opposed-phase pulse sequence (31 of 53, sensitivity 58 % vs 30 of 53, sensitivity 57 %, respectively). Two lesions not seen with opposed-phase imaging were detected with in-phase imaging. Conversely, one lesion not seen on in-phase imaging was detected on opposed-phase imaging so that the combination of in-phase and opposed-phase imaging yielded detection of 32 of 53 lesions (sensitivity 60 %). Qualitatively, lesion conspicuity was similar with both techniques. However, in-phase images showed better lesion conspicuity than opposed-phase images in 9 cases, and opposed-phase images showed better lesion conspicuity than in-phase images in 7 cases. No definite advantage (at a significant level) emerged between in-phase and opposed-phase spoiled GRE imaging. Because differences in lesion conspicuity and lesion detection may be observed with the two techniques in individual cases, MR evaluation of patients with focal hepatic lesion should include both in-phase and opposed-phase spoiled GRE imaging. Received 30 October 1996; Revision received 6 January 1997; Accepted 8 January 1997     

Gadobenate dimeglumine-enhanced liver MR imaging: value of dynamic and delayed imaging for the characterization and detection of focal liver lesions

The aim of this study was to determine the value of delayed-phase imaging (DPI) of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging for the evaluation of focal hepatic tumors compared with precontrast imaging and early dynamic phase imaging. The MR images were obtained in 48 patients with 98 focal hepatic tumors. Three-dimensional gradient-echo (GRE) imaging obtained before and 30, 60, and 1 h after administration of 0.1 mmol/kg of gadobenate dimeglumine. Each image set was analyzed qualitatively (lesion detection, conspicuity, delineation, and enhancement pattern on DPI) and quantitatively [signal-to-noise ratio (SNR), tumor–liver contrast-to-noise ratio (CNR)]. Improved lesion-to-liver contrast during the dynamic phase imaging was observed compared with precontrast images. The DPI showed a homogeneous enhancement of liver parenchyma and distinctive enhancement features of focal liver lesions: metastases (85%) showed a target shaped enhancement, and hepatocellular carcinomas (HCCs) showed an inhomogeneous (58%) or homogeneous enhancement (21%). The DPI showed better performance for the detection of metastases than other images by increasing lesion delineation (p<0.05). The absolute CNR of metastasis measured from periphery of the tumors on DPI was greater than precontrast and arterial phase imaging (p<0.05). The Gd-BOPTA during both dynamic and delayed phases provides valuable information for the characterization of focal liver lesions, and furthermore, Gd-BOPTA-enhanced DPI contributed to the improved detection of liver metastasis compared to precontrast and early dynamic imaging.     

T2-Weighted Liver MRI Using the MultiVane Technique at 3T: Comparison with Conventional T2-Weighted MRI

Objective

To assess the value of applying MultiVane to liver T2-weighted imaging (T2WI) compared with conventional T2WIs with emphasis on detection of focal liver lesions.

Materials and Methods

Seventy-eight patients (43 men and 35 women) with 86 hepatic lesions and 20 pancreatico-biliary diseases underwent MRI including T2WIs acquired using breath-hold (BH), respiratory-triggered (RT), and MultiVane technique at 3T. Two reviewers evaluated each T2WI with respect to artefacts, organ sharpness, and conspicuity of intrahepatic vessels, hilar duct, and main lesion using five-point scales, and made pairwise comparisons between T2WI sequences for these categories. Diagnostic accuracy (Az) and sensitivity for hepatic lesion detection were evaluated using alternative free-response receiver operating characteristic analysis.

Results

MultiVane T2WI was significantly better than BH-T2WI or RT-T2WI for organ sharpness and conspicuity of intrahepatic vessels and main lesion in both separate reviews and pairwise comparisons (p < 0.001). With regard to motion artefacts, MultiVane T2WI or BH-T2WI was better than RT-T2WI (p < 0.001). Conspicuity of hilar duct was better with BH-T2WI than with MultiVane T2WI (p = 0.030) or RT-T2WI (p < 0.001). For detection of 86 hepatic lesions, sensitivity (mean, 97.7%) of MultiVane T2WI was significantly higher than that of BH-T2WI (mean, 89.5%) (p = 0.008) or RT-T2WI (mean, 84.9%) (p = 0.001).

Conclusion

Applying the MultiVane technique to T2WI of the liver is a promising approach to improving image quality that results in increased detection of focal liver lesions compared with conventional T2WI.     

Evaluation of Focal Cervical Spinal Cord Lesions in Multiple Sclerosis: Comparison of White Matter–Suppressed T1 Inversion Recovery Sequence versus Conventional STIR and Proton Density–Weighted Turbo Spin-Echo Sequences

BACKGROUND AND PURPOSE:Conventional MR imaging of the cervical spinal cord in MS is challenged by numerous artifacts and interreader variability in lesion counts. This study compares the relatively novel WM-suppressed T1 inversion recovery sequence with STIR and proton density–weighted TSE sequences in the evaluation of cervical cord lesions in patients with MS.MATERIALS AND METHODS:Retrospective blinded analysis of cervical cord MR imaging examinations of 50 patients with MS was performed by 2 neuroradiologists. In each patient, the number of focal lesions and overall lesion conspicuity were measured in the STIR/proton density–weighted TSE and WM-suppressed T1 inversion recovery sequence groups. Independent side-by-side comparison was performed to categorize the discrepant lesions as either “definite” or “spurious.” Lesion contrast ratio and edge sharpness were independently calculated in each sequence.RESULTS:Substantial interreader agreement was noted on the WM-suppressed T1 inversion recovery sequence (κ = 0.82) compared with STIR/proton density–weighted TSE (κ = 0.52). Average lesion conspicuity was better on the WM-suppressed T1 inversion recovery sequence (conspicuity of 3.1/5.0 versus 3.7/5.0, P < .01, in the WM-suppressed T1 inversion recovery sequence versus STIR/proton density–weighted TSE, respectively). Spurious lesions were more common on STIR/proton density–weighted TSE than on the WM-suppressed T1 inversion recovery sequence (23 and 30 versus 3 and 4 by readers 1 and 2, respectively; P < .01). More “definite” lesions were missed on STIR/proton density–weighted TSE compared with the WM-suppressed T1 inversion recovery sequence (37 and 38 versus 3 and 6 by readers 1 and 2, respectively). Lesion contrast ratio and edge sharpness were highest on the WM-suppressed T1 inversion recovery sequence.CONCLUSIONS:There is better interreader consistency in the lesion count on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density–weighted TSE sequences. The focal cord lesions are visualized with better conspicuity due to better contrast ratio and edge sharpness. There are fewer spurious lesions on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density–weighted TSE. The WM-suppressed T1 inversion recovery sequence could potentially be substituted for either STIR or proton density–weighted TSE sequences in routine clinical protocols.

The cervical spinal cord is commonly affected in multiple sclerosis, which is often associated with an increase in clinical disability.^1–3 A focal form of involvement is more common in the relapsing-remitting variant of MS compared with the other less common MS subtypes.⁴ MS lesions undergo complex cycles of inflammation, followed by variable extent of repair and, therefore, have heterogeneity in the prolongation of T1 and T2 relaxation times, which influence their conspicuity on the standard MR imaging sequences such as STIR and proton density–weighted TSE (PDWTSE).The PDWTSE sequence with a lower TE is better than the longer TE T2-weighted sequences in the detection of focal MS lesions in the spinal cord.^5,6 STIR has intrinsic sensitivity to T1 shortening effects in addition to T2 prolongation effects and improves the lesion contrast compared with T2-weighted sequences, translating to a better interreader agreement in the assessment of the extent of disease.⁷ Nevertheless, artifacts and lower lesion conspicuity prevalent on these sequences may cause variability in the clinical evaluation of lesion burden, which is difficult to resolve in the absence of a true reference standard.⁸ Reliable characterization of the lesion burden on follow-up examinations is therefore important for assessing treatment efficacy and optimizing treatment strategies.Many novel sequences have been devised attempting to improve imaging quality and lesion conspicuity with fewer artifacts and with a reasonable acquisition time. In a smaller study population, the WM-suppressed T1 inversion recovery (WMS) sequence has shown improvement in lesion conspicuity over STIR and dual-echo fast spin-echo.⁹ While the principles of the contrast mechanism on WMS are similar to those on STIR, the sequence parameters of WMS are optimized for better intramedullary imaging. In WMS, the section-selective inversion pulse is applied at 385 ms to suppress the background signal from white matter, whereas in STIR, it is applied at 160 ms to optimize fat suppression.¹⁰ A shorter TE is used in WMS compared with STIR or PDWTSE, which further increases the T1-weighting of the sequence, which acts as the main contrast mechanism in this long TR/short TE sequence.^11,12 MS lesions have increased T1 relaxation times and thus are not suppressed with a white matter selective inversion recovery suppression pulse. There is a need for larger scale evaluation of WMS for clinical utility in routine practice against the standard sequences (STIR and PDWTSE) in the detection of MS cord lesions. The purpose of this retrospective study was to compare the utility of WMS compared with routinely used STIR and PDWTSE sequences in the evaluation of focal cervical cord lesions is MS.     

Comparison of conventional fast spin echo, single-shot two-dimensional and three-dimensional half-fourier RARE for T2-weighted female pelvic imaging

PURPOSE: To evaluate the usefulness of the three-dimensional half-Fourier RARE sequence in comparison with single-shot two-dimensional half-Fourier RARE and conventional fast spin echo (FSE) for female pelvic imaging. MATERIALS AND METHODS: Imaging with all sequences was performed in 146 patients with 166 focal lesions on a 1.5-T system. The images were compared on the basis of quality, lesion conspicuity, and lesion to the uterus contrast-to-noise ratio (CNR). RESULTS: The sharpness of intrapelvic organs on the three-dimensional half-Fourier RARE sequence was better than that on two-dimensional half-Fourier RARE and worse than that on FSE. Motion-related artifacts for three-dimensional half-Fourier RARE were more frequent than those for two-dimensional half-Fourier RARE. There was no statistical difference between the three-dimensional half-Fourier RARE sequence and FSE in regard to lesion conspicuity and overall image quality. The CNR of leiomyoma to myometrium and cervical cancer to cervical stroma was the highest with three-dimensional half-Fourier RARE (P< 0.05). CONCLUSION: The three-dimensional half-Fourier RARE sequence generates images with higher contrast and better image resolution than two-dimensional-RARE. The three-dimensional data set provided images that can be observed in any orientation without acquiring an additional scan by using the multiplanar reconstruction (MPR) method.     

Can ultrasound distinguish between dermatofibroma and subcutaneous epidermal tumors? - Imaging features and reproducibility

BackgroundWe evaluated ultrasound (US) features of dermatofibroma and epidermal tumor (ET). We also evaluated the reproducibility of each US findings.Materials and methodsWe retrospectively assessed US findings of 30 surgically confirmed dermatofibromas and 44 ETs, measuring the lesion (i.e., the depth and the length of the lesion) and calculating the depth to length ratio (DLR). We then determined the sharpness and the shape of the lesion. Finally, we assessed whether the lesion appeared with a “more-than-half sign” (involving more than 50% of the dermal layer) or a “submarine sign” (focal projection to skin). We used Pearson's chi-squared test to analyze the US findings (i.e., presence of more-than-half sign or submarine sign and margin sharpness) between dermatofibroma and ET. Inter-observer agreement of the image findings was assessed using kappa statistics.ResultsThe submarine sign and margin sharpness of ET lesions and the more-than-half sign and submarine sign in dermatofibroma, respectively, showed almost perfect agreement. Also, the more-than-half sign and shape of the lesion in ET and the margin sharpness and shape of the lesion in dermatofibroma showed substantial agreement. The measurements of DLRs showed excellent reproducibility. There were no significant differences of DLRs between two groups (p values = 0.512, 0.671, respectively). The more-than-half sign was observed more frequently in the context of dermatofibroma to a statistically significant degree (p < 0.001), while the submarine sign was statistically more common in relation to ET together with greater margin sharpness (p = 0.021 and <0.001, respectively).ConclusionsMore-than-half signs are common in dermatofibroma while submarine sign and sharp margin are common in ET. Each finding showed high reproducibility and can be useful as a sonographic marker for differentiation between ET and dermatofibroma.     

Phase-inversion tissue harmonic imaging compared to fundamental B-mode ultrasound in the evaluation of the pathology of large and small bowel

Our purpose was to compare phase-inversion harmonic imaging (PIHI) with conventional B-mode ultrasound (US) regarding image quality in the evaluation of bowel pathology. Forty-one patients prospectively underwent intestinal ultrasound scans with US and PIHI in randomly chosen order. Crucial technical parameters were standardized. Bowel morphology as well as perienteric pathology and complications were documented. In 24 cases, the ultrasound results were compared to those of other imaging modalities. Three radiologists evaluated (1) overall image quality, (2) lesion conspicuity and diagnostic confidence, and (3) detection of free fluid on hardcopy films. The ratings for image quality were compared using the two-sample paired t test for means and Bowkers test for symmetry (p=0.05). Compared to US, PIHI provided significantly better overall image quality, lesion conspicuity and diagnostic confidence, as well as better detection of free fluid (p< 0.05). Bowel wall pathology, detected by both modalities, showed good correlation to additional imaging modalities. In 12 patients (29.3%), a gain of crucial diagnostic information was observed with PIHI when compared to US. PIHI significantly enhances sonography of the intestine by offering better overall image quality, better visualization of bowel pathology and associated changes. Additionally, PIHI adds crucial diagnostic information in several patients.     

The influence of MR field strength on the detection of focal liver lesions with superparamagnetic iron oxide

The purpose of this study was to compare the value of low- vs high-field MR systems in the detection of focal liver lesions after IV administration of iron oxide particles. A prospective study was undertaken which included 20 patients with focal liver lesions on CT or US, or strong clinical suspicion of focal liver disease. Iron oxide particles were administered in an IV drip infusion over 30 min. Magnetic resonance imaging was subsequently performed on a 0.2 and a 1.5-T system. Both examinations were performed in one session. Turbo spin-echo T2-weighted sequences were used for further analysis (at 0.2 T: TR 4050 ms, TE 96 ms; 1.5 T: TR 3000 ms, TE 103 ms). After randomisation, images were analysed by two blinded readers. The evaluation included lesion counts, determination of lesion conspicuity and overall image quality (both graded on a scale 1–5). Quantitative analysis was performed on 29 lesions. Lesion-to-liver signal intensity and contrast-to-noise ratios (CNRs) were calculated. The total lesion count (cumulative counts for two observers) was 59 on the high-field system and 63 on the low-field system. Statistical analysis showed no significant difference. On both systems median value for lesion conspicuity was 3. No statistically significant difference was found. Global image quality was rated higher on the high-field system: 3 vs 2 for the low-field system (p = 0.0017). Quantitative analysis showed no significant difference for lesion-to-liver signal intensity ratios or CNRs. Although subjective image quality is significantly better on the high-field system, this does not result in better lesion detection or better lesion conspicuity. No significant difference in objective quantitative parameters was found in our series. Received 25 June 1996; Revision received 28 October 1996; Accepted 25 November 1996     

Free-breathing contrast-enhanced T1-weighted gradient-echo imaging with radial k-space sampling for paediatric abdominopelvic MRI

Objective

To compare the image quality of contrast-enhanced abdominopelvic 3D fat-suppressed T1-weighted gradient-echo imaging with radial and conventional Cartesian k-space acquisition schemes in paediatric patients.

Methods

Seventy-three consecutive paediatric patients were imaged at 1.5 T with sequential contrast-enhanced T1-weighted Cartesian (VIBE) and radial gradient echo (GRE) acquisition schemes with matching parameters when possible. Cartesian VIBE was acquired as a breath-hold or as free breathing in patients who could not suspend respiration, followed by free-breathing radial GRE in all patients. Two paediatric radiologists blinded to the acquisition schemes evaluated multiple parameters of image quality on a five-point scale, with higher score indicating a more optimal examination. Lesion presence or absence, conspicuity and edge sharpness were also evaluated. Mixed-model analysis of variance was performed to compare radial GRE and Cartesian VIBE.

Results

Radial GRE had significantly (all P?<?0.001) higher scores for overall image quality, hepatic edge sharpness, hepatic vessel clarity and respiratory motion robustness than Cartesian VIBE. More lesions were detected on radial GRE by both readers than on Cartesian VIBE, with significantly higher scores for lesion conspicuity and edge sharpness (all P?<?0.001).

Conclusion

Radial GRE has better image quality and lesion conspicuity than conventional Cartesian VIBE in paediatric patients undergoing contrast-enhanced abdominopelvic MRI.

Key Points

? Numerous techniques are required to provide optimal MR images in paediatric patients. ? Radial free-breathing contrast-enhanced acquisition demonstrated excellent image quality. ? Image quality and lesion conspicuity were better with radial than Cartesian acquisition. ? More lesions were detected on contrast-enhanced radial than on Cartesian acquisition. ? Radial GRE can be used for performing abdominopelvic MRI in paediatric patients.     

Superparamagnetic iron oxide-enhanced liver magnetic resonance imaging: comparison of 1.5 T and 3.0 T imaging for detection of focal malignant liver lesions

OBJECTIVES: We sought to compare the image quality, lesion conspicuity, and the diagnostic performance of 1.5 T and 3.0 T superparamagnetic iron oxide-enhanced liver magnetic resonance imaging (MRI) for detecting focal malignant hepatic lesions. MATERIALS AND METHODS: A total of 35 patients with pathologically proven liver malignancy underwent both 1.5 and 3.0 T SPIO-enhanced MRI. The diagnostic accuracy was evaluated using the alternative-free response receiver operating characteristic method. Image artifacts, quality, and the lesion conspicuity were analyzed. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the lesion were calculated. RESULTS: No significant difference of area under ROC curve (Az value) was noted. The mean SNR and CNR of the lesions was higher in the 3.0 T sets. There was no difference between the 1.5 T and the 3.0 T image sets for lesion conspicuity, but the image quality was better on 1.5 T. Motion and susceptibility artifacts were more frequent on 3.0 T. CONCLUSION: Diagnostic accuracies of the SPIO-enhanced MRI were equivalent on the 1.5 T and 3.0 T image sets. More prominent artifacts on 3.0 T superparamagnetic iron oxide-enhanced liver MRI counteracted advantage of higher SNR and CNR of 3.0 T.     

Tissue harmonic imaging sonography of breast lesions: Improved margin analysis, conspicuity, and image quality compared to conventional ultrasound

The purpose of this preference study is to determine if tissue harmonic imaging (THI) is preferred over conventional sonography for imaging breast masses. A prospective evaluation of 73 identical image pairs (one obtained with conventional sonography, one with THI sonography) was performed, examining 25 cysts, 36 solid masses, and 12 indeterminate lesions. Each image was evaluated for lesion contrast, margins, and overall image quality using a graduated score. Statistical analysis was performed using a modified t test. For cystic and solid lesions, THI was preferred for lesion conspicuity, margin, and overall quality (P<.001). For indeterminate lesions, THI was significantly preferred for lesion conspicuity and overall quality (P<.05), but the preference for margins was not significant. Overall, THI of breast lesions was significantly preferred for lesion contrast and margin evaluation compared to conventional sonography. This modality deserves further evaluation and may improve detection and evaluation of breast lesions.     

Feasibility of application of sensitivity encoding to the breath-hold T2-weighted turbo spin-echo sequence for evaluation of focal hepatic tumors

OBJECTIVE: The purpose of this study is to assess the feasibility of the application of sensitivity encoding (SENSE) to the T2-weighted breath-hold turbo spin-echo (BHTSE) sequence for evaluating focal hepatic lesions. MATERIALS AND METHODS: Thirty consecutive patients with 43 focal liver lesions underwent BHTSE, BHTSE using SENSE with the conventional parameters, and BHTSE using SENSE with increased matrix and reduced echo-train length (ETL). There were 23 hepatocellular carcinomas in 21 patients, 10 hemangiomas in six, and 10 metastases in three. The images were compared quantitatively by measuring the signal-to-noise ratio (SNR) of the liver and the lesion and the lesion-liver contrast-to-noise ratio (CNR) and qualitatively by evaluating image quality, lesion conspicuity, artifact, and lesion detectability. RESULTS: The SNR of lesions and the lesion-liver CNR were highest on BHTSE using SENSE with increased matrix and reduced ETL, which were significantly higher than conventional BHTSE (p <0.05). In qualitative analysis, the image quality and conspicuity of malignant lesions with BHTSE using SENSE with increased matrix and reduced ETL were better than with BHTSE and BHTSE using SENSE with the conventional parameter (p <0.05). The image artifacts were lower with two BHTSEs using SENSE than with BHTSE (p <0.05). Lesion conspicuity of malignancy on BHTSE using SENSE with the conventional parameter was superior to those on BHTSE (p <0.05). Although there was no significant difference in the lesion detectability among the three images, two malignant lesions were clearly depicted on BHTSE using SENSE with increased matrix and reduced ETL. CONCLUSION: The application of SENSE to BHTSE can provide high-quality liver imaging with decreased acquisition time compared with conventional BHTSE.