Microwave ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma undetectable by conventional ultrasonography

Objectives

To evaluate the efficiency and feasibility of microwave (MW) ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma (HCC) undetectable by conventional ultrasonography.

Methods

18 patients with 18 HCC nodules (undetectable on conventional US but detectable by intravenous contrast-enhanced CT or MRI) were enrolled in this study. Before MW ablation, US images and MRI or CT images were synchronized using the internal markers at the best timing of the inspiration. Thereafter, MW ablation was performed under real-time virtual navigation system guidance. Therapeutic efficacy was assessed by the result of contrast-enhanced imagings after the treatment.

Results

The target HCC nodules could be detected with fusion images in all patients. The time required for image fusion was 8–30 min (mean, 13.3 ± 5.7 min). 17 nodules were successfully ablated according to the contrast enhanced imagings 1 month after ablation. The technique effectiveness rate was 94.44% (17/18). The follow-up time was 3–12 months (median, 6 months) in our study. No severe complications occurred. No local recurrence was observed in any patients.

Conclusions

MW ablation assisted by a real-time virtual navigation system is a feasible and efficient treatment of patients with HCC undetectable by conventional ultrasonography.     

Use of contrast-enhanced ultrasonography with a perflubutane-based contrast agent performed one day after transarterial chemoembolization for the early assessment of residual viable hepatocellular carcinoma

Objective

We evaluated the efficacy of contrast-enhanced ultrasonography (US), compared with contrast-enhanced computed tomography (CT), for early assessments after transarterial chemoembolization (TACE) for the treatment of hypervascular hepatocellular carcinoma (HCC) lesions.

Subjects and methods

Thirty-two patients with 59 HCC lesions who were scheduled to receive TACE were enrolled in this prospective study. TACE was performed by injecting a mixture of iodized oil and miriplatin hydrate, followed by a gelatin sponge. Digital subtraction angiography (DSA) and/or contrast-enhanced CT were performed 2–6 months after TACE and were used as the reference standard for residual HCC; the detection rates for residual viable HCC using contrast-enhanced US with a perflubutane-based contrast agent and a high mechanical index (MI) mode performed one day after TACE were also compared with those obtained using contrast-enhanced CT performed one month after TACE. The comparisons were made using the McNemar test.

Results

Forty-seven (79.7%) of the 59 HCC lesions were diagnosed as having residual viability based on DSA and contrast-enhanced CT findings obtained 2–6 months after TACE. Eight (17.0%) of the 47 HCC lesions that were diagnosed as having residual viability using one-day contrast-enhanced US were not detected using one-month contrast-enhanced CT because of artifacts produced by the high attenuation of the iodized oil. The detection rate for residual HCC lesions using one-day contrast-enhanced US (95.7%, 45/47) was significantly higher than that using one-month contrast-enhanced CT (78.7%, 37/47) (P < 0.05).

Conclusion

Contrast-enhanced US performed one day after TACE is more sensitive than contrast-enhanced CT performed one month after TACE for detecting residual viable HCC.     

Treatment response assessment of radiofrequency ablation for hepatocellular carcinoma: usefulness of virtual CT sonography with magnetic navigation

Purpose

Virtual CT sonography using magnetic navigation provides cross sectional images of CT volume data corresponding to the angle of the transducer in the magnetic field in real-time. The purpose of this study was to clarify the value of this virtual CT sonography for treatment response of radiofrequency ablation for hepatocellular carcinoma.

Patients and methods

Sixty-one patients with 88 HCCs measuring 0.5–1.3 cm (mean ± SD, 1.0 ± 0.3 cm) were treated by radiofrequency ablation. For early treatment response, dynamic CT was performed 1–5 days (median, 2 days). We compared early treatment response between axial CT images and multi-angle CT images using virtual CT sonography.

Results

Residual tumor stains on axial CT images and multi-angle CT images were detected in 11.4% (10/88) and 13.6% (12/88) after the first session of RFA, respectively (P = 0.65). Two patients were diagnosed as showing hyperemia enhancement after the initial radiofrequency ablation on axial CT images and showed local tumor progression shortly because of unnoticed residual tumors. Only virtual CT sonography with magnetic navigation retrospectively showed the residual tumor as circular enhancement. In safety margin analysis, 10 patients were excluded because of residual tumors. The safety margin more than 5 mm by virtual CT sonographic images and transverse CT images were determined in 71.8% (56/78) and 82.1% (64/78), respectively (P = 0.13). The safety margin should be overestimated on axial CT images in 8 nodules.

Conclusion

Virtual CT sonography with magnetic navigation was useful in evaluating the treatment response of radiofrequency ablation therapy for hepatocellular carcinoma.     

Radiofrequency ablation of hepatocellular carcinoma: therapeutic response using contrast-enhanced coded phase-inversion harmonic sonography

OBJECTIVE: This study was performed to evaluate the usefulness of contrast-enhanced coded phase-inversion harmonic sonography in assessing the therapeutic response of percutaneous radiofrequency ablation in patients with hepatocellular carcinoma. SUBJECTS AND METHODS: Sixty-seven patients with a total of 107 examinations on 91 hepatocellular carcinoma nodules underwent coded harmonic angio, a technique of coded phase-inversion harmonic sonography, using the IV microbubble contrast agent Levovist before and after percutaneous radiofrequency ablation. The intratumoral blood vessels and tumor parenchymal stain were detected in the early arterial phase and the late vascular phase, respectively. The results of contrast-enhanced imaging with coded harmonic angio were compared with those of three-phase dynamic CT. RESULTS: Before treatment, all examined 107 hepatocellular carcinoma nodules were found to be hypervascular on contrast-enhanced imaging with coded harmonic angio. After radiofrequency ablation, contrast-enhanced coded harmonic angio detected persistent signal enhancement in 41 examined nodules (38.3%), whereas this technique showed no intratumoral enhancement in the remaining 66 (61.7%) examined nodules. Compared with dynamic CT, the sensitivity, specificity, and diagnostic accuracy of contrast-enhanced coded harmonic angio were 95.3%, 100%, and 98.1%, respectively. With contrast-enhanced coded harmonic angio, we found that it was difficult to identify the safety margin that can be detected on dynamic CT. CONCLUSION: Contrast-enhanced imaging with coded harmonic angio may provide an alternative approach that has high diagnostic agreement with dynamic CT in assessing the therapeutic effect of radiofrequency ablation in hypervascular hepatocellular carcinomas, in spite of having limitations in identifying the safety margin.     

Clinical utility of three-dimensional contrast-enhanced ultrasound in the differentiation between noninvasive and invasive neoplasms of urinary bladder

Objectives

The purpose of this study was to evaluate the effectiveness of three-dimensional contrast-enhanced ultrasound in differentiating invasive and noninvasive neoplasms of urinary bladder.

Methods

A total of 60 lesions in 60 consecutive patients with bladder tumors received three dimensional ultrasonography, low acoustic power contrast enhanced ultrasonography and low acoustic power three-dimensional contrast-enhanced ultrasound examination. The IU22 ultrasound scanner and a volume transducer were used and the ultrasound contrast agent was SonoVue. The contrast-specific sonographic imaging modes were PI (pulse inversion) and PM (power modulation). The three dimensional ultrasonography, contrast enhanced ultrasonography, and three-dimensional contrast-enhanced ultrasound images were independently reviewed by two readers who were not in the images acquisition. Images were analyzed off-site. A level of confidence in the diagnosis of tumor invasion of the muscle layer was assigned on a 5° scale. Receiver operating characteristic analysis was used to assess overall confidence in the diagnosis of muscle invasion by tumor. Kappa values were used to assess inter-readers agreement. Histologic diagnosis was obtained for all patients.

Results

Final pathologic staging revealed 44 noninvasive tumors and 16 invasive tumors. Three-dimensional contrast-enhanced ultrasound depicted all 16 muscle-invasive tumors. The diagnostic performance of three-dimensional contrast-enhanced ultrasound was better than those of three dimensional ultrasonography and contrast enhanced ultrasonography. The receiver operating characteristic curves were 0.976 and 0.967 for three-dimensional contrast-enhanced ultrasound, those for three dimensional ultrasonography were 0.881 and 0.869, those for contrast enhanced ultrasonography were 0.927 and 0.929. The kappa values in the three dimensional ultrasonography, contrast enhanced ultrasonography and three-dimensional contrast-enhanced ultrasound for inter-reader agreements were 0.717, 0.794 and 0.914.

Conclusion

Three-dimensional contrast-enhanced ultrasound imaging, with contrast-enhanced spatial visualization is clinical useful for differentiating invasive and noninvasive neoplasms of urinary bladder objectively.     

Percutaneous treatment of hepatocellular carcinoma in patients with cirrhosis: A comparison of the safety of cryoablation and radiofrequency ablation

Purpose

To compare the safety of image-guided percutaneous cryoablation and radiofrequency ablation in the treatment of hepatocellular carcinoma in patients with cirrhosis.

Materials and methods

This retrospective HIPAA-compliant study received institutional review board approval. Forty-two adult patients with cirrhosis underwent image-guided percutaneous ablation of hepatocellular carcinoma from 2003 to 2011. Twenty-five patients underwent 33 cryoablation procedures to treat 39 tumors, and 22 underwent 30 radiofrequency ablation procedures to treat 39 tumors. Five patients underwent both cryoablation and radiofrequency ablation procedures. Complication rates and severity per procedure were compared between the ablation groups. Potential confounding patient, procedure, and tumor-related variables were also compared. Statistical analyses included Kruskal–Wallis, Wilcoxon rank sum, and Fisher's exact tests. Two-sided P-values <0.05 were considered significant.

Results

The overall complication rates, 13 (39.4%) of 33 cryoablation procedures versus eight (26.7%) of 30 radiofrequency ablation procedures and severe/fatal complication rates, two (6.1%) of 33 cryoablation procedures versus one (3.3%) of 30 radiofrequency ablation procedures, were not significantly different between the ablation groups (both P = 0.26). Severe complications included pneumothoraces requiring chest tube insertion during two cryoablation procedures. One death occurred within 90 days of a radiofrequency ablation procedure; all other complications were managed successfully.

Conclusion

No significant difference was seen in the overall safety of image-guided percutaneous cryoablation and radiofrequency ablation in the treatment of hepatocellular carcinoma in patients with cirrhosis.     

Combined versus single interventional therapies in treatment of hepatic malignant tumors

Aim of work

To evaluate the effectiveness of transarterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) in treatment of malignant hepatic focal lesions versus use of either TACE or RFA alone.

Material and methods

The study included 57 patients; 53 with hepatocellular carcinoma (HCC), 3 with hepatic metastases, and one case with cholangiocarcinoma.They were divided into three groups according to the technique of treatment: the first group (25 patients) was treated by RF alone, the second group (17 patients) was treated by TACE alone and the third group (15 patients) was treated by combined RFA and TACE.

Results

In cases treated with RF only there was good response in 20% of hypervascular tumors and 28% of hypovascular tumors. In cases treated with TACE there was 47.06% good response in hypervascular tumors and 11.76% in hypovascular tumors. While in combined use of TACE and RF there was 60% good response in hypervascular tumors, and 26.66% in hypovascular tumors.

Conclusion

Combined interventional therapies are superior to any single therapy in treatment of either hypervascular or hypovascular hepatic malignant tumors.     

Contrast-enhanced ultrasonography findings using a perflubutane-based contrast agent in patients with early hepatocellular carcinoma

Objective

We evaluated the contrast-enhanced ultrasonography (US) imaging features of early hepatocellular carcinomas (HCCs) and compared these findings with those obtained using contrast-enhanced computed tomography (CT).

Subjects and methods

Forty-three patients with 52 early HCCs with a mean maximal diameter of 15.6 mm were enrolled in this retrospective study. After confirming the location of the target lesion using fusion imaging combining conventional US and hepatobiliary phase of contrast-enhanced magnetic resonance (MR) imaging with gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid, we evaluated findings of contrast-enhanced US using a perflubutane-based contrast agent. The contrast-enhanced US detection rates for hyper-vascularity in early HCCs were compared with those obtained for contrast-enhanced CT.

Results

Transient hypo-vascularity subsequent to iso-vascularity during arterial phase and iso-vascularity during portal and post-vascular phases were the predominant contrast-enhanced US findings seen for 25 (48.1%) of the 52 early HCCs. Nine (17.3%) showed iso-vascularity during all three phases, while 1 (1.9%) showed hypo-vascularity during all three phases. The remaining 17 (32.7%) showed partial or whole hyper-vascularity during arterial phase, iso-vascularity during portal phase, and iso- or hypo-vascularity during post-vascular phase. The detection rate for the hyper-vascularity of early HCCs using contrast-enhanced US (32.7%, 17/52) was significantly higher than that obtained using contrast-enhanced CT (21.2%, 11/52) (P < 0.05 by McNemar test).

Conclusion

Hypo-vascularity, iso-vascularity, and hyper-vascularity were observed during the arterial phase of contrast-enhanced US in 50.0%, 17.3%, and 32.7% of the early HCCs, respectively. Contrast-enhanced US was more sensitive than contrast-enhanced CT for the detection of hyper-vascularity in early HCCs. Of note, early HCCs might not exhibit the early arterial enhancement that is generally considered to be a typical finding for HCCs.     

Role of Sonazoid-enhanced three-dimensional ultrasonography in the evaluation of percutaneous radiofrequency ablation of hepatocellular carcinoma

Objective

We investigated contrast-enhanced three-dimensional ultrasonography (CE 3D US) with contrast agent Sonazoid for evaluating the effect of percutaneous radiofrequency (RF) ablation of hepatocellular carcinomas (HCCs).

Methods

63 HCCs were treated by US-guided percutaneous RF ablation. CE 3D US after bolus injection of 0.2 mL of Sonazoid was performed 5-7 days before and 1 day after RF ablation. CE 3D computed tomography (CT) was performed 5-7 days before and 1 month after the ablation, and during the follow-up period. Multiplanar images in three orthogonal planes and US/CT angiograms were reconstructed on both modalities. Two blinded observers reviewed the images on both modalities to evaluate the ablation effects.

Results

After RF ablation, the evaluation on CE 3D US and that on CE 3D CT achieved concordance in 61 lesions. Among them, 59 lesions were detected with the absence of tumor vessels and tumor enhancement and evaluated as adequate ablation, and the remaining two lesions were detected with residual tumors. The kappa value for agreement between the findings on the two modalities was 0.65. When 1-month CE 3D CT scans were used as reference standard, the sensitivity, specificity, and accuracy of 1-day CE 3D US for detecting adequate ablation were 97%, 100%, and 97%, respectively.

Conclusion

By demonstrating the ablated areas and residual tumors in three dimensions, CE 3D US with Sonazoid was shown to be useful for evaluating the effect of RF ablation of HCCs, and there was good concordance with the results obtained by CE 3D CT.     

Fusion of multislice computed tomography and electroanatomical mapping data for 3D navigation of left and right atrial catheter ablation

Purpose

To assess whether fusion of multislice computed tomography (CT) images with electroanatomical (EA)-mapping data using a new image integration module (CartoMerge™) is feasible and accurate to navigate ablation catheters in right and left atrial catheter ablation.

Material and methods

Twenty-four patients were examined with ECG-gated cardiac multislice CT (64 mm × 0.6 mm, 0.33 s) 1 day before left atrial (LA) (15 patients) radiofrequency or right atrial cavotricuspid isthmus ablation (9 patients). CT data were fused with the non-fluoroscopic EA-mapping data by using dedicated software (CartoMerge™) and the value of CT was analysed.

Results

In 23/24 (96%) patients, CT images could be fused with the EA-map. The alignment error was 2.16 ± 0.35 mm. In 15/15 (100%) patients, CT added relevant anatomical information regarding the course of the esophagus or the pulmonary veins before LA-ablation. CT added useful information in only 3/8 (37.5%) of patients undergoing right atrial cavotricuspid isthmus ablation.

Conclusion

3D-navigation of RF-ablation catheters in the atria assisted by image fusion of multislice CT with EA-mapping data is feasible and accurate. CT added relevant anatomical information about the left atrium and the pulmonary veins before LA-ablation, CT also provided information about the course of the esophagus which might help to avoid thermal injury. CT image fusion might be of minor value before right atrial cavotricuspid isthmus catheter ablation.     

Hepatocellular carcinoma treated with radiofrequency ablation: comparison of pulse inversion contrast-enhanced harmonic sonography, contrast-enhanced power Doppler sonography, and helical CT.

OBJECTIVE: The purpose of this study was to compare the efficacy of contrast-enhanced pulse inversion harmonic imaging with contrast-enhanced power Doppler sonography and helical CT to determine incomplete local treatment after radiofrequency ablation in patients with hepatocellular carcinoma. MATERIALS AND METHODS: Thirty-five consecutive patients (24 men and 11 women; mean age, 64 years) with 43 hepatocellular carcinomas (3.6 +/- 1.1 cm) were treated using internally cooled radiofrequency ablation therapy. Therapeutic response was evaluated at 4 months with dual-phase contrast-enhanced helical CT, conventional power Doppler Sonography, and pulse inversion harmonic imaging using a sonographic contrast agent (SH-508). CT and sonographic studies were reviewed separately in random order by four radiologists at different consensus conferences. Sensitivity and specificity of the sonographic methods were determined using CT as a gold standard and results were compared using the McNemar test. RESULTS: CT examinations identified residual tumor in 12 lesions (27.9%). Although conventional contrast-enhanced power Doppler sonography identified residual viable tumor foci in four incompletely treated lesions (9.3%), contrast-enhanced pulse inversion harmonic imaging identified residual tumoral enhancement in 10 lesions (23.3%). Thus, the sensitivity of pulse inversion harmonic imaging (83.3%) was significantly greater (p < 0.05) for detecting residual nonablated tumor compared with conventional contrast-enhanced power Doppler sonography. CONCLUSION: Our study suggests that contrast-enhanced pulse inversion harmonic imaging may enable the detection of residual nonablated tumor in more cases than contrast-enhanced power Doppler sonography and may ultimately prove to be a useful adjunct for percutaneous ablation therapies. Nevertheless, contrast-enhanced axial imaging (CT or MR imaging) is currently the most sensitive test for managing thermal ablation for patients with hepatocellular carcinoma.     

Indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced computed tomography: Assessment of the additional diagnostic value of contrast-enhanced ultrasound in the non-cirrhotic liver

Objective

To assess the additional diagnostic value of contrast-enhanced ultrasound (CEUS) in the characterization of indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced computed tomography (CT).

Methods

Fifty-five solid hepatic lesions (1–4 cm in diameter) in 46 non-cirrhotic patients (26 female, 20 male; age ± SD, 55 ± 10 years) underwent CEUS after being detected on contrast-enhanced CT which was considered as non-diagnostic after on-site analysis. Two blinded independent readers assessed CT and CEUS scans and were asked to classify retrospectively each lesion as a malignant or benign based on reference diagnostic criteria for the different hepatic lesion histotypes. Diagnostic accuracy and confidence (area – A_z – under ROC curve) were assessed by using gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging (n = 30 lesions), histology (n = 7 lesions), or US follow-up (n = 18 lesions) as the reference standards.

Results

Final diagnoses included 29 hemangiomas, 3 focal nodular hyperplasias, 1 hepatocellular adenoma, and 22 metastases. The additional review of CEUS after CT images improved significantly (P < .05) the diagnostic accuracy (before vs after CEUS review = 49% [20/55] vs 89% [49/55] – reader 1 and 43% [24/55] vs 92% [51/55] – reader 2) and confidence (A_z, 95% Confidence Intervals before vs after CEUS review = .773 [.652–.895] vs .997 [.987–1] – reader 1 and .831 [.724–.938] vs .998 [.992–1] – reader 2).

Conclusions

CEUS improved the characterization of indeterminate solid hepatic lesions identified on non-diagnostic contrast-enhanced CT by identifying some specific contrast enhancement patterns.     

Value of fusion of PET and MRI for staging of endometrial cancer: Comparison with F-FDG contrast-enhanced PET/CT and dynamic contrast-enhanced pelvic MRI

Purpose

To investigate the diagnostic value of retrospective fusion of pelvic MRI and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET images for assessment of locoregional extension and nodal staging of endometrial cancer.

Materials and methods

Thirty patients with biopsy-proven endometrial cancer underwent preoperative contrast-enhanced PET/CT (PET/ceCT) and pelvic dynamic contrast-enhanced MRI for initial staging. Diagnostic performance of PET/ceCT, contrast-enhanced MRI, and retrospective image fusion from PET and MRI (fused PET/MRI) for assessing the extent of the primary tumor (T stage) and metastasis to regional LNs (N stage) was evaluated by two experienced readers. Histopathological and follow-up imaging results were used as the gold standard. The McNemar test was employed for statistical analysis.

Results

Fused PET/MRI and MRI detected 96.7% of the primary tumors, whereas PET/ceCT detected 93.3%. Accuracy for T status was 80.0% for fused PET/MRI, and MRI proved significantly more accurate than PET/ceCT, which had an accuracy of 60.0% (p = 0.041). Patient-based sensitivity, specificity and accuracy for detecting pelvic nodal metastasis were 100%, 96.3% and 96.7% for both fused PET/MRI and PET/ceCT, and 66.7%, 100% and 96.7% for MRI, respectively. These three parameters were not statistically significant (p = 1).

Conclusion

Fused PET/MRI, which complements the individual advantages of MRI and PET, is a valuable technique for assessment of the primary tumor and nodal staging in patients with endometrial cancer.     

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.     

Local thermal ablation of renal cell carcinoma

Purpose

With evolving local thermal ablation technology, the clinical application of thermal ablation has been actively investigated in the treatment for renal cell carcinoma. We review the evolution and current status of radiofrequency ablation and microwave ablation for renal cell carcinoma.

Materials and methods

All articles published in English on radiofrequency ablation or microwave ablation as a treatment for renal cell carcinoma were identified with a MEDLINE^® and PubMed^® search from 1990 to 2010.

Results

Local thermal ablation has several advantages, including keeping more normal renal units, relatively simple operation, easy tolerance, fewer complications, a shorter hospitalization and convalescence period. Long-term data has determined radiofrequency ablation is responsible for poor surgical candidates with renal cell carcinoma, however, tumor size, location and shape might affect the efficacy of radiofrequency ablation. Microwave ablation can induce large ablation volumes and yield good local tumor control. Associated complications appear to be low.

Conclusions

Local ablative approaches seem to represent an attractive alternative to extirpative surgery for the treatment of small renal neoplasms in select patients. Potential developments include concepts to improve the accuracy and effectiveness of thermal ablation by improving the guiding, monitoring capabilities and detection capacity of multi-center lesions to provide at least equivalent cancer control to conventional surgery.     

Ultrasound elastography and contrast-enhanced ultrasound in infants,children and adolescents

Objective

To describe prerequisites, use, and safety of ultrasound elastography and contrast-enhanced ultrasound in infants, children, and adolescents.

Method

This review deals with two latest developments in ultrasonography in children. The principle of strain elastography, transient elastography, and acoustic radiation force imaging is discussed, including limitations, and advantages of the different techniques in diagnosing focal and diffuse organ disease. The intravesical (contrast-enhanced voiding ultrasonography) and intravascular use of contrast-media to outline blood, and urinary flow is described, with special emphasis on indications, off-label use, and diagnostic gain. Examples of indications for performing the advanced ultrasound techniques are presented.

Summary and conclusion

Latest developments in ultrasound machine engineering, and the availability of contrast-media that interact with ultrasound waves allow for assessment of tissue stiffness/elasticity properties, blood, and urinary flow. Thereby ultrasound is capable not only to depict morphology, but gives the additional information on organ, and focal lesion perfusion, and urinary flow dynamics. The information gap to other cross-sectional techniques such as magnetic resonance imaging, that make potential harmful sedation, and anaesthesia in the youngest children necessary, thereby gets closer.     

Findings of multidetector row computed tomography of HCCs treated by HIFU ablation

Purpose

We evaluated the efficacy of high-intensity focused ultrasound (HIFU) ablation for hepatocellular carcinoma (HCC), and a long-term study by follow-up multidetector-row computed tomography (CT) was conducted to evaluate the changes occurring in the treatment area following the HIFU ablation.

Materials and methods

HIFU ablation was carried out in 14 patients with small HCCs (≤3 lesions, ≤3 cm in diameter). The HIFU system (Chongqing Haifu Tech) was used under ultrasound guidance. The evaluations were performed by follow-up CT at 1 week, 1, 3, 6 and 12 months after the HIFU ablation.

Results

HIFU ablation was carried out successfully in 11 of the 14 patients. At 1 week after the HIFU, a peripheral rim enhancement was found in all cases (100%). This finding was persistent in 6 of the 11 cases (54.5%) at 1 month, and in 1 of the 11 (9%) cases at 3 months after HIFU ablation. In all cases, the rim enhancement disappeared by 6 or 12 months after the HIFU ablation. At the 12 months follow-up, a decrease in the diameter of the ablated lesions was found. The enhancement around the treated area was found to be persistent at the 12 months follow-up in the one case of recurrence of the treated site in which the safety margin was not sufficiently wide. During the follow-up period, there were 2 cases with residual of HCC tumors. We performed radiofrequency ablation (RFA) for these residual tumors after the HIFU ablation.

Conclusion

To ascertain the cause of the peripheral enhancement on follow-up CT images after the HIFU ablation, in particular, to determine whether it might be caused by residual tumor or recurrence at the treated site, careful follow-up is important, especially in cases where the safety margin of the ablated area was not sufficiently wide.     

Prospective evaluation of MRI,C-acetate PET/CT and contrast-enhanced CT for staging of bladder cancer

Purpose

To prospectively evaluate the diagnostic performance of magnetic resonance imaging (MRI), ¹¹C-acetate positron emission tomography/computed tomography (PET/CT) and contrast-enhanced CT for bladder cancer staging, using whole-mount pathologic review of radical cystectomy and pelvic lymph node specimens as the reference standard.

Materials and methods

The institutional review board approved this prospective study, which was compliant with the Health Insurance Portability and Accountability Act. Written informed consent was obtained from 16 patients with histologically confirmed bladder cancer who underwent MRI, ¹¹C-acetate PET/CT and contrast-enhanced CT before radical cystectomy and pelvic lymph node dissection. Before imaging 4/16 patients had received intravesical Bacillus Calmette-Guérin treatment, 6 had received systemic chemotherapy, 3 had received both and 3 had received neither. Measures of diagnostic performance including accuracy, sensitivity and specificity were estimated separately for each imaging modality.

Results

MRI correctly staged 56% of patients (9/16), overstaged 38% (6/16) and understaged 6% (1/16). CT correctly staged 50% of patients (8/16), overstaged 44% (7/16) and understaged 6% (1/16). In 9 patients, ¹¹C-acetate PET/CT showed uptake within the bladder wall; the uptake was true-positive in 7 patients and false-positive in 2 patients. Of the remaining 7 patients, 5 had true-negative and 2 had false-negative PET/CT results for cancer in the bladder wall. For all modalities, staging accuracy was reduced in patients with a history of prior intravesical and/or systemic chemotherapy.

Conclusion

In staging bladder cancer, MRI, ¹¹C-acetate PET/CT and CT displayed similar levels of accuracy. For all modalities, a history of intravesical and/or systemic chemotherapy affected staging accuracy.     

Castleman disease of the neck: CT and MR imaging findings

Objective

To characterize the computed tomography (CT) and magnetic resonance imaging (MRI) findings of Castleman disease of the neck.

Methods

The imaging findings of 21 patients with Castleman disease of the neck were reviewed retrospectively. Of the 21 patients, 16 underwent unenhanced and contrast-enhanced CT scans; 5 underwent unenhanced and contrast-enhanced MRI scans.

Results

The unenhanced CT images showed isolated or multiple well-defined homogenous mild hypodensity lesions in fifteen cases, and a heterogeneous nodule with central areas of mild hypodensity in one case. Calcification was not observed in any of the patients. In five patients, MR T1-weighted images revealed well-defined, homogeneous isointense or mild hyperintense lesions to the muscle; T2-weighted images showed these as intermediate hyperintense. Sixteen cases showed intermediate to marked homogeneous enhancement on contrast-enhanced CT or MR T1-weighted images. Of the other five cases that underwent double-phase CT scans, four showed mild or intermediate heterogeneous enhancement at the arterial phase, and homogeneous intermediate or marked enhancement at the venous phase; the remaining case showed mild and intermediate ring-enhancement with a central non-enhanced area at the arterial and venous phases, respectively.

Conclusion

Castleman disease of the neck can be characterized as solitary or multiple well-defined, mild hypodensity or homogeneous intense lesions on plain CT/MR scans, and demonstrates intermediate and marked enhancement on contrast-enhanced CT/MR scans. On double-phase CT scans, Castleman disease often demonstrates mild enhancement at the arterial phase, and gradually uniform enhancement at venous phase. Double-phase enhanced CT or MRI may help to differentiate Castleman disease from other diseases.     

Clinical utility of contrast-enhanced three-dimensional ultrasound imaging with Sonazoid: findings on hepatocellular carcinoma lesions

Objectives

We investigated clinical utility of contrast-enhanced three-dimensional ultrasound (CE 3D US) imaging with contrast medium Sonazoid for demonstrating characteristic enhancement of hepatocellular carcinoma (HCC).

Methods

Among 115 focal liver tumors undergoing CE 3D US imaging, 70 HCCs confirmed with contrast-enhanced multi-detector computed tomography, contrast-enhanced magnetic resonance imaging or histopathologic examination were retrospectively analyzed. CE 3D US imaging was performed using Autosweep 3D scan functionality in the early, middle and late phase, after bolus injection of 0.2 ml Sonazoid. The CE 3D tomographic images reconstructed in parallel slices and sonographic angiogram images were independently reviewed by two reviewers. Kappa values were used to assess inter-reviewers’ agreement.

Results

TUI images showed most of HCCs were detected with intratumoral vessels and early tumor enhancement in the early phase, expressed homogenous or heterogeneous tumor enhancement in the middle phase, and became hypoechoic or isoechoic in the late phase. The kappa values in the early, middle and late phase for inter-reviewer agreements regarding the characteristic enhancement of tumors were 0.817, 0.774, and 0.785. In addition, TUI images demonstrated satellite foci and tortuous tumor vessels in three orthogonal planes. Sonographic angiogram reconstructed by different rendering modes showed the vessels and tumor stain in spatial view. The spatial configuration of anatomic structures was revealed on basis of both TUI and sonographic angiogram images.

Conclusion

CE 3D US imaging, with spatial visualization, is clinically useful to exhibit the characteristic enhancement of HCC tumors objectively.