To improve clinical three-dimensional (3D) MR spectroscopic imaging with more accurate localization and faster acquisition schemes.

Institutional review board approval and patient informed consent were obtained. Data were acquired with a 3-T MR imager and a 32-channel head coil in phantoms, five healthy volunteers, and five patients with glioblastoma. Excitation was performed with localized adiabatic spin-echo refocusing (LASER) by using adiabatic gradient-offset independent adiabaticity wideband uniform rate and smooth truncation (GOIA-W[16,4]) pulses with 3.5-msec duration, 20-kHz bandwidth, 0.81-kHz amplitude, and 45-msec echo time. Interleaved constant-density spirals simultaneously encoded one frequency and two spatial dimensions. Conventional phase encoding (PE) (1-cm3 voxels) was performed after LASER excitation and was the reference standard. Spectra acquired with spiral encoding at similar and higher spatial resolution and with shorter imaging time were compared with those acquired with PE. Metabolite levels were fitted with software, and Bland-Altman analysis was performed.

Clinical 3D MR spectroscopic images were acquired four times faster with spiral protocols than with the elliptical PE protocol at low spatial resolution (1 cm3). Higher-spatial-resolution images (0.39 cm3) were acquired twice as fast with spiral protocols compared with the low-spatial-resolution elliptical PE protocol. A minimum signal-to-noise ratio (SNR) of 5 was obtained with spiral protocols under these conditions and was considered clinically adequate to reliably distinguish metabolites from noise. The apparent SNR loss was not linear with decreasing voxel sizes because of longer local T2* times. Improvement of spectral line width from 4.8 Hz to 3.5 Hz was observed at high spatial resolution. The Bland-Altman agreement between spiral and PE data is characterized by narrow 95% confidence intervals for their differences (0.12, 0.18 of their means). GOIA-W(16,4) pulses minimize chemical-shift displacement error to 2.1%, reduce nonuniformity of excitation to 5%, and eliminate the need for outer volume suppression.

The proposed adiabatic spiral 3D MR spectroscopic imaging sequence can be performed in a standard clinical MR environment. Improvements in image quality and imaging time could enable more routine acquisition of spectroscopic data than is possible with current pulse sequences.

© RSNA, 2011

To determine the precision of a three-dimensional (3D) method for measuring the growth rate of solid and subsolid nodules and its ability to detect abnormal growth rates.

This study was approved by the Institutional Research Board and was HIPAA compliant. Informed consent was waived. The growth rates of 123 lung nodules in 59 patients who had undergone lung cancer screening computed tomography (CT) were measured by using a 3D semiautomated computer-assisted volume method. Clinical stability was established with long-term CT follow-up (mean, 6.4 years ± 1.9 [standard deviation]; range, 2.0–8.5 years). A mean of 4.1 CT examinations per patient ± 1.2 (range, two to seven CT examinations per patient) was analyzed during 2.4 years ± 0.5 after baseline CT. Nodule morphology, attenuation, and location were characterized. The analysis of standard deviation of growth rate in relation to time between scans yielded a normative model for detecting abnormal growth.

Growth rate precision increased with greater time between scans. Overall estimate for standard deviation of growth rate, on the basis of 939 growth rate determinations in clinically stable nodules, was 36.5% per year. Peripheral location (P = .01; 37.1% per year vs 25.6% per year) and adjacency to pleural surface (P = .05; 38.9% per year vs 34.0% per year) significantly increased standard deviation of growth rate. All eight malignant nodules had an abnormally high growth rate detected. By using 3D volumetry, growth rate–based diagnosis of malignancy was made at a mean of 183 days ± 158, compared with radiologic or clinical diagnosis at 344 days ± 284.

A normative model derived from the variability of growth rates of nodules that were stable for an average of 6.4 years may enable identification of lung cancer.

© RSNA, 2011

Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11100878/-/DC1

To quantify a pseudoenhancement phenomenon observed during dynamic contrast material–enhanced ultrasonography (US) of the carotid artery, both in vitro and in vivo.

Ethical approval was obtained prior to commencing this prospective case series, and each patient gave written informed consent. Thirty-one patients with 50%–99% internal carotid artery stenosis underwent dynamic contrast-enhanced US of the carotid bifurcation with use of 2 mL of microbubbles. In the final 10 patients, an additional 1 mL bolus was administered after 15 minutes. Raw linear digital imaging and communications in medicine data were analyzed offline. Regions of interest were drawn within the common carotid artery lumen and immediately adjacent to the lumen in the near and far wall adventitia. Peak intensity was measured. An in vitro experiment with a single–channel flow phantom was also performed. This apparatus consisted of an 8-mm-diameter latex tube placed in a tissue-mimicking fluid. Microbubble concentrations of 0.02%, 0.1%, 0.5%, 1%, and 2% were pumped into the tube. Regions of interest were drawn in a similar fashion to the in vivo experiments, and peak intensity was measured. The Wilcoxon signed rank and paired t tests were used to compare the difference between the near and far wall signal intensities at each dose; a multiplication factor comparing near and far wall signal intensity was derived.

The far wall of the common carotid artery was significantly more echogenic than the near wall at 2 mL contrast agent doses (P < .0001, n = 31), and the far wall signal intensity increased synchronously with that of the lumen. The difference in signal intensity between near and far wall regions was significantly greater at 2 mL than at 1 mL (P = .012, n = 10). In vitro, the phantom tubing demonstrated a similar pattern and magnitude of enhancement to that seen in vivo.

A dose-dependent, nonlinear propagation artifact known as pseudoenhancement occurs in the far wall adventitia of the carotid artery and should not be mistaken as a marker of plaque vulnerability.

© RSNA, 2011

To quantitatively assess microvascular activation in the thickened ileal walls of patients with Crohn disease (CD) by using contrast-enhanced ultrasonography (US) and evaluate its correlation with widely used indexes of CD activity.

This prospective study was approved by the ethics committee, and written informed consent was obtained from all patients. The authors examined 54 consecutively enrolled patients (mean age, 35.29 years; age range, 18–69 years; 39 men, 15 women) with endoscopically confirmed CD of the terminal ileum. Ileal wall segments thicker than 3 mm were examined with low-mechanical-index contrast-enhanced US and a second-generation US contrast agent. The authors analyzed software-plotted time–enhancement intensity curves to determine the maximum peak intensity (MPI) and wash-in slope coefficient (β) and evaluated their correlation with (a) the composite index of CD activity (CICDA), (b) the CD activity index (CDAI), and (c) the simplified endoscopic score for CD (SES-CD, evaluated in 37 patients) for the terminal ileum. Statistical analysis was performed with the Mann-Whitney test, Spearman rank test, and receiver operating characteristic (ROC) analysis.

MPI and β coefficients were significantly increased in the 36 patients with a CICDA indicative of active disease (P < .0001 for both), the 33 patients with a CDAI of at least 150 (P < .032 and P < .0074, respectively), and the 26 patients with an SES-CD of at least 1 (P < .0001 and P < .002, respectively). ROC analysis revealed accurate identification (compared with CICDA) of active CD with an MPI threshold of 24 video intensity (VI) (sensitivity, 97%; specificity, 83%) and a β coefficient of 4.5 VI/sec (sensitivity, 86%; specificity, 83%).

Contrast-enhanced US of the ileal wall is a promising method for objective, reproducible assessment of disease activity in patients with ileal CD.

© RSNA, 2011

To compare prospectively the effects of radiofrequency (RF) ablation after transcatheter arterial chemoembolization (TACE) with those of RF ablation alone in the treatment of recurrent hepatocellular carcinoma (HCC).

This study was approved by the institutional ethics committee, and all patients gave written informed consent. From January 2002 to December 2006, 139 patients with recurrent HCC measuring 5 cm in diameter or smaller were randomized to receive either sequential TACE and RF ablation (sequential treatment group, n = 69) or RF ablation alone (RF ablation group, n = 70). The survival curves were constructed with the Kaplan-Meier method and compared by using the log-rank test. Bonferroni correction was applied when multiple comparisons were performed. P < .0083 (.05 ÷ 6) was considered indicative of a statistically significant difference.

The 1-, 3-, and 5-year overall survival rates were 94%, 69%, and 46%, respectively, for the sequential treatment group and 82%, 47%, and 36% for the RF ablation group (P = .037). The corresponding recurrence-free survival rates were 80%, 45%, and 40% for the sequential treatment group and 64%, 18%, and 18% for the ablation group (P = .005). At subgroup analyses, the overall survival for the sequential treatment group was better than that for the RF ablation group for patients with tumor recurrence 1 year or less after initial treatment (P = .004) and those with tumors measuring 3.1–5.0 cm (P = .002) but not for those with tumor recurrence more than 1 year after initial treatment (P = .421) and those with tumors 3.0 cm or smaller (P = .478). The recurrence-free survival in the sequential treatment group was better than that in the RF ablation group for patients with tumors measuring 3.1–5.0 cm (P < .001) but not for those with tumors 3.0 cm or smaller (P = .204). For recurrence-free survival, there was no significant difference between the two groups for patients with tumor recurrence 1 year or less or more than 1 year after initial treatment (P = .020 and P = .111, respectively). Logistic regression analysis showed that treatment allocation and the interval between initial treatment and tumor recurrence were significant prognostic factors for overall survival, whereas the interval between initial treatment and tumor recurrence, treatment allocation, and tumor size were significant prognostic factors for recurrence-free survival.

The efficacy of sequential TACE-RF ablation is better than that of RF ablation alone for recurrent HCC.

© RSNA, 2011

To evaluate the feasibility and efficacy of computed tomography (CT)-guided radiofrequency (RF) neurolysis (RFN) in the management of refractory inguinal neuralgia.

Local institutional review board approval was obtained and written informed consent was waived. Twelve patients 26–75 years of age with chronic (>6 months) inguinal pain refractory to specific medication were included between 2005 and 2011. Data on patient demographics, clinical history, and pain management history were retrospectively assessed. Pain was measured on a visual analog scale (VAS) from 0 to 10 before and immediately after the procedure and at 1, 3, 6, 9 and 12 months. Diagnosis was always confirmed by a positive nerve block test result. Ambulatory CT-guided RF was the rule.

Sixteen RFN procedures were performed. Pain was present for an average of 3.2 years (range: 2–8 years) prior to initial RFN. Mean VAS score before the procedure was 7.75 of 10. Immediate pain relief of 100% was achieved in all patients. Pain reduction at 1-, 3-, 6-, 9-, and 12-month follow-up was statistically significant. Important pain reduction (≥80%) was obtained in 75% of RFN procedures at 6-month follow-up and in 50% of cases at 12 months. The mean duration of pain relief was 11.8 months after RFN, with a maximum average pain reduction of 84.5%. No complications were noted during or after the procedure.

RFN with CT guidance is an effective technique in the management of refractory inguinal pain with lasting satisfactory pain reduction; it may be considered as an alternative treatment to surgery. These results should be confirmed in a controlled trial with a larger series of patients.

© RSNA, 2011

To identify differences in radiologic assessment methods and determine optimal imaging criteria for response evaluation in hepatocellular carcinoma (HCC) patients treated with chemoembolization.

Institutional review board approval was obtained, and patient informed consent was waived. The present study included 332 patients with intermediate stage HCC and Child-Pugh A cirrhosis who underwent serial chemoembolization. All measurable target lesions of 1 cm or larger in diameter were uni- and bidimensionally measured both at baseline and during follow-up. Intermodel agreement among the guidelines of the World Health Organization (WHO), Response Evaluation Criteria in Solid Tumors (RECIST), the European Association for the Study of the Liver (EASL), and modified RECIST (mRECIST) were examined. The most reliable model was selected on the basis of the correlation with survival prediction.

The values of comparisons among WHO, RECIST, and mRECIST guidelines were less than 0.20, whereas the value for the comparison of EASL and mRECIST guidelines was 0.94. In patients with a partial response (PR), stable disease (SD), or progressive disease (PD), compared with patients with a complete response (CR), hazard ratios (HRs) for survival were 2.99 (95% confidence interval [CI]: 2.14, 4.17), 3.49 (95% CI: 1.71, 7.10), and 15.63 (95% CI: 9.51, 25.69), respectively, for EASL criteria. In patients with a PR, SD, or PD, compared with patients with a CR, the HRs were 2.75 (95% CI: 1.96, 3.87), 6.32 (95% CI: 3.67, 10.90), and 16.06 (95% CI: 9.76, 26.43), respectively, for mRECIST guidelines (P < .001). The C index for the multivariate model was 0.76 (95% CI: 0.72, 0.79) for both EASL and mRECIST guidelines, thus exhibiting satisfactory capability to help predict survival. The Cox regression model revealed that both mRECIST and EASL guidelines were independent predictors of overall survival (P < .001 for both).

The enhancement models more accurately helped predict long-term survival in HCC patients treated with chemoembolization.

© RSNA, 2011