The Clinical Significance of Maximum Tumor Diameter on MRI in Men Undergoing Radical Prostatectomy or Definitive Radiotherapy for Locoregional Prostate Cancer

INTRODUCTION

Maximum tumor diameter (MTD) on pretreatment magnetic resonance imaging (MRI) has the potential to further risk stratify for men with prostate cancer (PCa) prior to definitive local therapy. We aim to evaluate the prognostic impact of radiographic maximum tumor diameter (MTD) in men with localized prostate cancer.

PATIENTS AND METHODS

From a single-center retrospective cohort of men receiving definitive treatment for PCa (radical prostatectomy [RP] or radiotherapy [RT]) with available pretreatment MRI, we conducted univariable and multivariable Cox proportional-hazards models for progression using clinical variables including age, NCCN risk group, radiographic extracapsular extension (ECE), radiographic seminal vesical invasion (SVI), and MTD. RP and RT cohorts were analyzed separately. Covariates were used in a classification and regression tree (CART) analysis and progression-free survival was estimated with the Kaplan-Meier method and groups were compared using log-rank tests.

RESULTS

The cohort included 631 patients (n = 428 RP, n = 203 RT). CART analysis identified 4 prognostic groups for patients treated with RP and 2 prognostic groups in those treated with RT. In the RP cohort, NCCN low/intermediate risk group patients with MTD>=15 mm had significantly worse PFS than those with MTD <= 14 mm, and NCCN high-risk patients with radiographic ECE had significantly worse PFS than those without ECE. In the RT cohort, PFS was significantly worse in the cohort with MTD >= 23 mm than those <= 22 mm.

CONCLUSION

Radiographic MTD may be a useful prognostic factor for patients with locoregional prostate cancer. This is the first study to illustrate that the importance of pretreatment tumor size may vary based on treatment modality.

The Effect of Maximum Tumor Diameter by MRI on Disease Control in Intermediate and High-risk Prostate Cancer Patients Treated With Brachytherapy Boost

BACKGROUND

Larger maximum tumor diameter (MTD) has been associated with worse prostate cancer (PCa) outcomes. However, the impact of MTD in PCa treated with external beam radiotherapy and brachytherapy boost (EBRT+BB) remains unknown.

MATERIALS AND METHODS

Patients with PCa treated with EBRT+BB were identified from an institutional database. Clinical data including MTD, age, androgen deprivation therapy (ADT) use, prostate specific antigen (PSA), International Society of Urologic Pathology (ISUP) group, clinical T-stage, and presence of adverse pathology on imaging were retrospectively collected. Multivariable and univariable cox proportional hazards models for biochemical failure (BF) and distant metastasis (DM) were produced with MTD grouped by receiver operating characteristic (ROC) cut-point. Cumulative hazard functions for BF and DM were compared with log-rank test and stratified by ISUP group.

RESULTS

Of 191 patients treated with EBRT+BB, 113 had MTD measurements available. Larger MTD was associated with increased ADT use and seminal vesicle involvement. ROC optimization identified MTD of 24 mm as the optimal cut-point for both BF and DM. MTD was independently associated with both BF (HR 8.61, P = .048, 95% CI 1.02-72.97) and DM (HR 8.55, P = .05, 95% CI 1.00-73.19). In patients with ISUP group 4 to 5 disease, MTD > 24 mm was independently associated with increased risk of DM (HR 10.13, P = .04, 95% CI 1.13-91.12).

CONCLUSIONS

This is the first study to evaluate MTD in the setting of EBRT+BB. These results demonstrate that MTD is independently associated with BF and metastasis. This suggests a possible role for MTD in risk assessment models and clinical decision-making for men receiving EBRT+BB.

The effect of maximum tumor diameter on disease control in intermediate and high-risk prostate cancer patients treated with brachytherapy boost

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Background: Larger maximum tumor diameter (MTD) has been associated with worse prostate cancer outcomes for those undergoing surgery as well as salvage radiation. MTD is also an important consideration for patients weighing active surveillance. However, the impact of MTD in intermediate and high-risk prostate cancer treated with external beam radiotherapy (EBRT) and brachytherapy boost is unknown. We set out to evaluate MTD of the dominant nodule on MRI as a prognostic factor in patients treated with EBRT and brachytherapy boost for localized prostate cancer. Methods: Patients with prostate cancer treated with EBRT and brachytherapy boost were identified from an institutional database. In patients with a pretreatment MRI, data on MTD were retrospectively collected. Clinical data including age, ADT use, pretreatment PSA, International Society of Urologic Pathology (ISUP) group, clinical T-stage, and presence of adverse pathology on imaging (either seminal vesicle invasion or extraprostatic extension) were also collected. Multivariable and univariable cox proportional hazards models for biochemical failure (BF) and distant metastasis (DM) were produced in patients with MTD grouped by receiver operating characteristic (ROC) cutpoint. Cumulative hazard functions for BF and DM were compared with log-rank test and stratified by ISUP group. Results: Of 191 patients treated with EBRT and brachytherapy boost, 113 had pretreatment MRI and available MTD measurement. Median follow up was 40 months (interquartile range 23-66 months) and median MTD was 17 mm (interquartile range 13-22mm). Increasing MTD was associated with higher T stage and increased ADT use. ROC cutpoint optimization identified MTD of 24mm to be the optimal cut-point for both BF and DM. On univariate log-rank analysis, patients with MTD > 24mm had higher 5-year BF (31% vs 4%, p = 0.004) and DM (21% vs 4%, p = 0.002) than those with MTD≤24. Stepwise multivariable cox model for BF (P = 0.130, HR 1.08, 95% CI 0.98-1.21) and DM (P = 0.115, HR 1.09, 95% CI 0.98-1.23), MTD did not demonstrate statistical significance when controlling for clinical t-stage, adverse pathologic features on imaging, ISUP group, and ADT use. However, in patients with ISUP group 4-5 disease, MTD > 24 was independently associated with increased risk of DM (P = 0.032, HR 1.18, 95% CI 1.01-1.37). Conclusions: This is the first study to evaluate MTD on MRI as a prognostic factor in the setting of brachytherapy boost. These results demonstrate that for patients treated with EBRT and brachytherapy boost, MTD is independently associated with risk for metastasis in patients with ISUP grade 4 and 5 disease. Although these results require further validation, this suggests a possible role for MTD as a factor in risk assessment models and clinical decision-making.

Consensus-based technical recommendations for clinical translation of renal BOLD MRI

Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65-74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.

Consensus-based technical recommendations for clinical translation of renal BOLD MRI

Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65-74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.

Comparison of Performance of Improved Serum Estimators of Glomerular Filtration Rate (GFR) to 99mTc-DTPA GFR Methods in Patients with Hepatic Cirrhosis

Glomerular filtration rate (GFR) measurements are critical in patients with hepatic cirrhosis but potentially erroneous when based on serum creatinine. New equations for estimated GFR (eGFR) have shown variable performance in cirrhotics, possibly because of inaccuracies in reference methods for measured GFR (mGFR). The primary objective was to compare the performance of 4 improved eGFR equations with a 1-compartment, 2-sample plasma slope intercept ^99mTc-DTPA mGFR method to determine whether any of the eGFR calculations could replace plasma ^99mTc-DTPA mGFR in patients with cirrhosis. The secondary objective was to test the hypothesis that mGFR using voluntary voided urine collections introduces error compared with plasma-only methods. Methods: Fifty-four patients with hepatic cirrhosis underwent mGFR determinations from 2 plasma samples at 1 and 3 h after intravenous administration of 185 MBq of ^99mTc-DTPA. GFR was also generated by a UV/P calculation derived from blood and urine samples. These mGFRs were compared with the eGFRs generated by 4 estimating equations: MDRD (Modified Diet in Renal Disease), CKD-EPI (Chronic Kidney Disease-Epidemiology Collaboration) (serum creatinine [SCr]), CKD-EPI (cystatin [CysC]), and CKD-EPI (CysC+SCr). eGFRs were compared with mGFRs by Pearson correlation, precision, bias, percentage bias, and accuracy (eGFRs varying by <10% [p10], <20% [p20] or <30% [p30] from the corresponding mGFR). Results: All eGFRs showed poorer performance when the UV/P ^99mTc-DTPA mGFR was used as the reference than when the plasma ^99mTc-DTPA mGFR was used. When compared with the plasma ^99mTc-DTPA mGFR method, the performance of all eGFR equations was superior to most published reports. There was a moderately good positive correlation between eGFRs and mGFRs. When compared with plasma ^99mTc-DTPA mGFR, precision of eGFRs was in the range of 14-20 mL/min and showed a negligible bias. Compared with the plasma ^99mTc-DTPA mGFR, CKD-EPI (CysC+SCr) showed the best overall performance and accuracy, at 85.19% (p30), 75.93% (p20), and 42.59% (p10). Conclusion: Estimating equations for measuring eGFR performed better than in most published reports, attributable to use of the plasma ^99mTc-DTPA mGFR method as a reference. CKD-EPI (CysC+SCr) eGFR showed the best overall performance. However, more discriminating methods may be required when accurate GFR measurements are necessary. mGFR measurements using urine collections may introduce error compared with plasma-only methods.

Fast Padé Transform Accelerated CSI for Hyperpolarized MRS

The fast Padé transform (FPT) is a method of spectral analysis that can be used to reconstruct nuclear magnetic resonance spectra from truncated free induction decay signals with superior robustness and spectral resolution compared with conventional Fourier analysis. The aim of this study is to show the utility of FPT in reducing of the scan time required for hyperpolarized ¹³C chemical shift imaging (CSI) without sacrificing the ability to resolve a full spectrum. Simulations, phantom, and in vivo hyperpolarized [1-¹³C] pyruvate CSI data were processed with FPT and compared with conventional analysis methods. FPT shows improved stability and spectral resolution on truncated data compared with the fast Fourier transform and shows results that are comparable to those of the model-based fitting methods, enabling a reduction in the needed acquisition time in ¹³C CSI experiments. Using FPT can reduce the readout length in the spectral dimension by 2-6 times in ¹³C CSI compared with conventional Fourier analysis without sacrificing the spectral resolution. This increased speed is crucial for ¹³C CSI because T1 relaxation considerably limits the available scan time. In addition, FPT can also yield direct quantification of metabolite concentration without the additional peak analysis required in conventional Fourier analysis.

Synchronous Radial 1H and 23Na Dual-Nuclear MRI on a Clinical MRI System, Equipped With a Broadband Transmit Channel

The purpose of this work was to synchronously acquire proton (1H) and sodium (23Na) image data on a 3T clinical MRI system within the same sequence, without internal modification of the clinical hardware, and to demonstrate synchronous acquisition with 1H/23Na-GRE imaging with Cartesian and radial k-space sampling. Synchronous dual-nuclear imaging was implemented by: mixing down the 1H signal so that both the 23Na and 1H signal were acquired at 23Na frequency by the conventional MRI system; interleaving 1H/23Na transmit pulses in both Cartesian and radial sequences; and using phase stabilization on the 1H signal to remove mixing effects. The synchronous 1H/23Na setup obtained images in half the time necessary to sequentially acquire the same 1H and 23Na images with the given setup and parameters. Dual-nuclear hardware and sequence modifications were used to acquire 23Na images within the same sequence as 1H images, without increases to the 1H acquisition time. This work demonstrates a viable technique to acquire 23Na image data without increasing 1H acquisition time using minor additional custom hardware, without requiring modification of a commercial scanner with multinuclear capability.

Optimization of saturation-recovery dynamic contrast-enhanced MRI acquisition protocol: monte carlo simulation approach demonstrated with gadolinium MR renography

Dynamic contrast-enhanced (DCE) MRI is widely used for the measurement of tissue perfusion and to assess organ function. MR renography, which is acquired using a DCE sequence, can measure renal perfusion, filtration and concentrating ability. Optimization of the DCE acquisition protocol is important for the minimization of the error propagation from the acquired signals to the estimated parameters, thus improving the precision of the parameters. Critical to the optimization of contrast-enhanced T1 -weighted protocols is the balance of the T1 -shortening effect across the range of gadolinium (Gd) contrast concentration in the tissue of interest. In this study, we demonstrate a Monte Carlo simulation approach for the optimization of DCE MRI, in which a saturation-recovery T1 -weighted gradient echo sequence is simulated and the impact of injected dose (D) and time delay (TD, for saturation recovery) is tested. The results show that high D and/or high TD cause saturation of the peak arterial signals and lead to an overestimation of renal plasma flow (RPF) and glomerular filtration rate (GFR). However, the use of low TD (e.g. 100 ms) and low D leads to similar errors in RPF and GFR, because of the Rician bias in the pre-contrast arterial signals. Our patient study including 22 human subjects compared TD values of 100 and 300 ms after the injection of 4 mL of Gd contrast for MR renography. At TD = 100 ms, we computed an RPF value of 157.2 ± 51.7 mL/min and a GFR of 33.3 ± 11.6 mL/min. These results were all significantly higher than the parameter estimates at TD = 300 ms: RPF = 143.4 ± 48.8 mL/min (p = 0.0006) and GFR = 30.2 ± 11.5 mL/min (p = 0.0015). In conclusion, appropriate optimization of the DCE MRI protocol using simulation can effectively improve the precision and, potentially, the accuracy of the measured parameters. Copyright © 2016 John Wiley & Sons, Ltd.

T2* Measurement bias due to concomitant gradient fields

PURPOSE

To demonstrate that concomitant magnetic fields can cause significant spatially dependent biases in T2* relaxometry measurements with implications for clinical applications such as BOLD and dynamic susceptibility contrast-enhanced MRI.

THEORY AND METHODS

After developing a theoretical framework for intravoxel dephasing and signal loss from concomitant magnetic fields, this framework and the effect of concomitant fields on T2* are validated with phantom experiments and numerical simulation. In lower leg and renal T2* mapping, we quantify measurement bias for imaging protocols with high gradient amplitude multiecho readouts, comparable to those used in clinical applications.

RESULTS

Concordance between phantom experiment and numerical simulation validate the theoretical framework. Changes in T2* measured in the lower leg and kidney varied by up to 15% and 35%, respectively, as a result of concomitant gradient effects when compared with the control measurements.

CONCLUSION

Concomitant magnetic fields produced by imaging gradient coils can cause clinically significant T2* mapping errors when high amplitude, long duration gradient waveforms are used. While we have shown that measurement biases can be quite large, modification of imaging parameters can potentially reduce concomitant field-induced measurement errors to acceptable levels. Magn Reson Med 77:1562-1572, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Low Physical Function in Maintenance Hemodialysis Patients Is Independent of Muscle Mass and Comorbidity

OBJECTIVES

It is unknown whether muscle wasting accounts for impaired physical function in adults on maintenance hemodialysis (MHD).

DESIGN

Observational study.

SETTING

Outpatient dialysis units and a fall clinic.

SUBJECTS

One hundred eight MHD and 122 elderly nonhemodialysis (non-HD) participants.

EXPOSURE VARIABLE

Mid-thigh muscle area was measured by magnetic resonance imaging.

MAIN OUTCOME MEASURE

Physical function was measured by distance walked in 6 minutes.

RESULTS

Compared with non-HD elderly participants, MHD participants were younger (49.2 ± 15.8 vs. 75.3 ± 7.1 years; P < .001) and had higher mid-thigh muscle area (106.2 ± 26.8 vs. 96.1 ± 21.1 cm2; P = .002). However, the distance walked in 6 minutes was lower in MHD participants (322.9 ± 110.4 vs. 409.0 ± 128.3 m; P < .001). In multiple regression analysis adjusted for demographics, comorbid conditions, and mid-thigh muscle area, MHD patients walked significantly less distance (-117 m; 95% confidence interval: -177 to -56 m; P < .001) than the non-HD elderly.

CONCLUSIONS

Even when compared with elderly non-HD participants, younger MHD participants have poorer physical function that was not explained by muscle mass or comorbid conditions. We speculate that the uremic milieu may impair muscle function independent of muscle mass. The mechanism of impaired muscle function in uremia needs to be established in future studies.

Associations of body size and body composition with functional ability and quality of life in hemodialysis patients

BACKGROUND AND OBJECTIVES

Modifiable factors, such as body size and body composition, could influence physical function and quality of life in patients undergoing maintenance hemodialysis (MHD).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

From January 2008 to June 2012, in body mass index (BMI), waist circumference (WC), and magnetic resonance imaging measurements of midthigh muscle area (MTMA) and intra-abdominal fat area (IAFA) were obtained at baseline in 105 MHD patients. Six-minute walk distances and physical and mental component scores (PCS and MCS) from the Short Form-12 questionnaire were obtained at baseline and 6 and 12 months. Separate mixed-effects regression models were used to relate baseline BMI, WC, and IAFA with baseline and the average of follow-up 6-minute walk distances and PCS and MCS after adjustment for baseline covariates and MTMA.

RESULTS

for baseline covariates and baseline MTMA, each SD increase in baseline BMI was inversely associated with baseline (-31.5 m; 95% confidence interval [95% CI], -53.0 to -10.0 m) and follow-up (-36.9 m; 95% CI, -54.6 to -19.2 m) 6-minute walk distances. Results were similar for WC and IAFA. In each of these models, each SD increase in MTMA had a strong positive association with 6-minute walk distance. Adiposity measures were not associated with baseline or follow-up PCS and MCS. After adjustment for baseline BMI, each SD increase in baseline MTMA was associated with higher baseline PCS score (3.78; 95% CI, 0.73 to 6.82) and MCS (3.75; 95% CI, 0.44 to 7.05) but had weaker associations with follow-up PCS and MCS.

CONCLUSIONS

Body size and composition are significantly associated with physical functioning and quality of life. Interventions that improve muscle mass and decrease obesity might improve these measures in patients undergoing MHD.

New magnetic resonance imaging methods in nephrology

Established as a method to study anatomic changes, such as renal tumors or atherosclerotic vascular disease, magnetic resonance imaging (MRI) to interrogate renal function has only recently begun to come of age. In this review, we briefly introduce some of the most important MRI techniques for renal functional imaging, and then review current findings on their use for diagnosis and monitoring of major kidney diseases. Specific applications include renovascular disease, diabetic nephropathy, renal transplants, renal masses, acute kidney injury, and pediatric anomalies. With this review, we hope to encourage more collaboration between nephrologists and radiologists to accelerate the development and application of modern MRI tools in nephrology clinics.

Measurement of renal tissue oxygenation with blood oxygen level-dependent MRI and oxygen transit modeling

Blood oxygen level-dependent (BOLD) MRI data of kidney, while indicative of tissue oxygenation level (Po2), is in fact influenced by multiple confounding factors, such as R2, perfusion, oxygen permeability, and hematocrit. We aim to explore the feasibility of extracting tissue Po2 from renal BOLD data. A method of two steps was proposed: first, a Monte Carlo simulation to estimate blood oxygen saturation (SHb) from BOLD signals, and second, an oxygen transit model to convert SHb to tissue Po2. The proposed method was calibrated and validated with 20 pigs (12 before and after furosemide injection) in which BOLD-derived tissue Po2 was compared with microprobe-measured values. The method was then applied to nine healthy human subjects (age: 25.7 ± 3.0 yr) in whom BOLD was performed before and after furosemide. For the 12 pigs before furosemide injection, the proposed model estimated renal tissue Po2 with errors of 2.3 ± 5.2 mmHg (5.8 ± 13.4%) in cortex and -0.1 ± 4.5 mmHg (1.7 ± 18.1%) in medulla, compared with microprobe measurements. After injection of furosemide, the estimation errors were 6.9 ± 3.9 mmHg (14.2 ± 8.4%) for cortex and 2.6 ± 4.0 mmHg (7.7 ± 11.5%) for medulla. In the human subjects, BOLD-derived medullary Po2 increased from 16.0 ± 4.9 mmHg (SHb: 31 ± 11%) at baseline to 26.2 ± 3.1 mmHg (SHb: 53 ± 6%) at 5 min after furosemide injection, while cortical Po2 did not change significantly at ∼58 mmHg (SHb: 92 ± 1%). Our proposed method, validated with a porcine model, appears promising for estimating tissue Po2 from renal BOLD MRI data in human subjects.

A 3 T sodium and proton composite array breast coil

PURPOSE

The objective of this study was to determine whether a sodium phased array would improve sodium breast MRI at 3 T. The secondary objective was to create acceptable proton images with the sodium phased array in place.

METHODS

A novel composite array for combined proton/sodium 3 T breast MRI is compared with a coil with a single proton and sodium channel. The composite array consists of a 7-channel sodium receive array, a larger sodium transmit coil, and a 4-channel proton transceive array. The new composite array design utilizes smaller sodium receive loops than typically used in sodium imaging, uses novel decoupling methods between the receive loops and transmit loops, and uses a novel multichannel proton transceive coil. The proton transceive coil reduces coupling between proton and sodium elements by intersecting the constituent loops to reduce their mutual inductance. The coil used for comparison consists of a concentric sodium and proton loop with passive decoupling traps.

RESULTS

The composite array coil demonstrates a 2-5× improvement in signal-to-noise ratio for sodium imaging and similar signal-to-noise ratio for proton imaging when compared with a simple single-loop dual resonant design.

CONCLUSION

The improved signal-to-noise ratio of the composite array gives breast sodium images of unprecedented quality in reasonable scan times.

A phase I/II study of decitabine in combination with panitumumab in patients with wild-type (wt) KRAS metastatic colorectal cancer

PURPOSE

KRAS mutations are predictive of lack of response to monoclonal antibodies (mAb) against EGFR in metastatic colorectal cancer (mCRC). Most wild-type KRAS patients, however, are also resistant. Retrospective data suggest that EGFR silencing play a role in resistance to therapy. We conducted a study to evaluate the safety and efficacy of decitabine (a hypomethylating agent) in combination with panitumumab (mAb against EGFR) in mCRC patients.

EXPERIMENTAL DESIGN

20 patients with wild-type KRAS mCRC were included in this phase I/II study. Patients were treated with decitabine at 45 mg/m(2) IV over 2 h on day 1 and 15 and panitumumab 6 mg/kg IV over 1 h on day 8 and 22 every 28 days. Blood samples were collected at baseline, day 8, 15 and 22. Quantitative polymerase chain reaction was used to measure promoter-specific methylation in peripheral-blood cells (PBMCs).

RESULTS

The most common adverse events were grade 1-2 (rash and hypomagnesemia); 3 (16 %) patients had grade III-IV neutropenia including one patient with neutropenic fever. Two of 20 patients (10 %) had a partial response. Both had previously received cetuximab. Ten patients had stable disease (3 of them longer than 16 weeks). Decreased methylation of the MAGE promoter was not evidenced in PBMCs.

CONCLUSIONS

The combination of decitabine and panitumumab was well tolerated and showed activity in wild-type KRAS mCRC patients previously treated with cetuximab. Target modulation in surrogate tissues was not achieved and tumor biopsies were not available. Future studies evaluating hypomethylating agents in combination with EGFR mAb in patients with mCRC are warranted.

3D multi-parametric breast MRI segmentation using hierarchical support vector machine with coil sensitivity correction

RATIONALE AND OBJECTIVES

The goal of the study is to develop a technique to achieve accurate volumetric breast tissue segmentation using magnetic resonance imaging (MRI) data. This segmentation can be useful to aid in the diagnosis of breast cancers and to assess breast cancer risk based on breast density. Tissue segmentation is also essential for development of acoustic and thermal models used in magnetic resonance guided high-intensity focused ultrasound treatment of breast lesions.

MATERIALS AND METHODS

In addition to commonly used T1-, T2-, and proton density-weighted images, three-point Dixon water- and fat-only images were also included as part of the multiparametric inputs to a tissue segmentation algorithm using a hierarchical support vector machine (SVM). The effectiveness of a variety of preprocessing schemes was evaluated through two in vivo datasets. The performance of the hierarchical SVM was investigated and compared to the conventional classification algorithms-conventional SVM and fuzzy C-mean (FCM).

RESULTS

The need for co-registration, zero-filled interpolation, coil sensitivity correction, and optimal SNR reconstruction before the final stage classification was demonstrated. The overlap ratios of the hierarchical SVM, conventional SVM and FCM were 93.25%-94.08%, 81.68-92.28%, and 75.96%-91.02%, respectively. Classification outputs from in vivo experiments showed that the presented methodology is consistent and outperforms other algorithms.

CONCLUSION

The presented hierarchical SVM-based technique showed promising results in automatically segmenting breast tissues into fat, fibroglandular tissue, skin, and lesions. The results provide evidence that both the multiparametric breast MRI inputs and the preprocessing procedures contribute to the high accuracy of tissue classification.

Testing targeted demethylation to overcome resistance to epidermal growth factor receptor (EGFR) blocking agents in wild-type (wt) KRAS metastatic colorectal cancer patients (mCRC)

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Background: Panitumumab, a monoclonal antibody against EGFR, led to improved progression-free survival (PFS) in patients with (wt)KRAS mCRC. However, the benefit of panitumumab is limited to a not yet identified small subset of (wt)KRAS patients. The CpG island methylator phenotype (CIMP-high) is present in 15-20% of CRC patients. Epigenetic silencing through methylation of PTEN and/or genes in the EGFR pathway might play a role in resistance to therapy. We assessed whether decitabine (a hypomethylating agent) reverted resistance to anti-EGFR therapies. Methods: Patients (n=19) with (wt)KRAS mCRC previously treated with anti-EGFR therapies were enrolled. Patients were treated with decitabine 45mg/kg IV on day (d)1 and d15 and panitumumab 6mg/kg IV on d8 and d22 q28days. Peripheral blood, skin biopsies and buccal smear samples were collected on d1, d8, d15 and d22 to assess methylation changes in PTEN, RASSF1A and SOCS-1 in response to therapy. Tumors were analyzed for PIK3CA mutations using PCR-based DNA sequencing of exon 9 and 20 by PCR as well as for PTEN by immunohistochemistry. Results: Median age was 53 (range 31-72). Eleven (58%) patients were female; 15 (79%) had ECOG PS 1; 3 (16%) had ECOG PS 2; and 1 had ECOG PS 0. Median number of previous therapies was 4. The most common toxicities were rash (68%), hypomagnesemia (26%) and neutropenia (10%) (all grade 1-2). The most common grade 3-4 toxicities were neutropenic fever (5%) and hypomagnesemia (5%). Of 19 (wt)KRAS mCRC patients previously treated with anti-EGFR therapies, 2 (11%) had a partial response (PR) (-50% and -30%, respectively) and 3 (16%) had stable disease (SD) >4 months (7.8, 5.9 and 4.2 months). Both responders were (wt)PIK3CA and (wt)PTEN. Clinical benefit rate (PR+SD) was 27%. Median PFS was 60 days (95% CI 45.4-74.5), similar to median PFS after last anti-EGFR therapy, 61d (95% CI 50.6-71.3). Conclusions: Panitumumab + decitabine is an active combination in a subset of patients with mCRC previously treated with anti-EGFR therapies (2 PRs in this population). Efficacy assessment in an anti-EGFR therapy naïve population is warranted. Methylation studies are ongoing.

Diffusion-weighted imaging of human carotid artery using 2D single-shot interleaved multislice inner volume diffusion-weighted echo planar imaging (2D ss-IMIV-DWEPI) at 3T: diffusion measurement in atherosclerotic plaque

PURPOSE

To determine if 2D single-shot interleaved multislice inner volume diffusion-weighted echo planar imaging (ss-IMIV-DWEPI) can be used to obtain quantitative diffusion measurements that can assist in the identification of plaque components in the cervical carotid artery.

MATERIALS AND METHODS

The 2D ss-DWEPI sequence was combined with interleaved multislice inner volume region localization to obtain diffusion weighted images with 1 mm in-plane resolution and 2 mm slice thickness. Eleven subjects, six of whom have carotid plaque, were studied with this technique. The apparent diffusion coefficient (ADC) images were calculated using DW images with b = 10 s/mm(2) and b = 300 s/mm(2).

RESULTS

The mean ADC measurement in normal vessel wall of the 11 subjects was 1.28 +/- 0.09 x 10(-3) mm(2)/s. Six of the 11 subjects had carotid plaque and ADC measurements in plaque ranged from 0.29 to 0.87 x 10(-3) mm(2)/s. Of the 11 common carotid artery walls studied (33 images), at least partial visualization of the wall was obtained in all ADC images, more than 50% visualization in 82% (27/33 images), and full visualization in 18% (6/33 images).

CONCLUSION

2D ss-IMIV-DWEPI can perform diffusion-weighted carotid magnetic resonance imaging (MRI) in vivo with reasonably high spatial resolution (1 x 1 x 2 mm(3)). ADC values of the carotid wall and plaque are consistent with similar values obtained from ex vivo endarterectomy specimens. The spread in ADC values obtained from plaque indicate that this technique could form a basis for plaque component identification in conjunction with other MRI/MRA techniques.

Rapid simultaneous acquisition of T1 and T2 mapping images using multishot double spin-echo EPI and automated variations of TR and TE (ms-DSEPI-T12)

A rapid method of simultaneous T(1) and T(2) measurement is presented which uses a segmented echo-planar readout with varying repetition times (TR) and echo times (TE). This method is useful in T(1) mapping for analysis of dynamic contrast enhanced MRI (DCE-MRI), where T(1) can be used to estimate contrast agent concentration. In the application of this method to dynamic imaging, the equilibrium magnetization is measured on pre-contrast images and incorporated into post-contrast T(1) calculations for improved accuracy. Simultaneous T(2) measurement allows correction of T(2) effects in the T(1) map which may occur at high contrast agent concentrations, and is performed without significant imaging time penalty. Phantom and in vivo results show the usefulness of this technique for analysis of contrast enhancement kinetics. Accurate rapid contrast agent concentration measurement may be useful for analyzing the distribution and kinetics of contrast agents or labeled pharmaceuticals.

Comparison of combined aerobic and high-force eccentric resistance exercise with aerobic exercise only for people with type 2 diabetes mellitus

BACKGROUND AND PURPOSE

The purpose of this study was to compare the outcomes between a diabetes exercise training program using combined aerobic and high-force eccentric resistance exercise and a program of aerobic exercise only.

SUBJECTS AND METHODS

Fifteen participants with type 2 diabetes mellitus (T2DM) participated in a 16-week supervised exercise training program: 7 (mean age=50.7 years, SD=6.9) in a combined aerobic and eccentric resistance exercise program (AE/RE group) and 8 (mean age=58.5 years, SD=6.2) in a program of aerobic exercise only (AE group). Outcome measures included thigh lean tissue and intramuscular fat (IMF), glycosylated hemoglobin, body mass index (BMI), and 6-minute walk distance.

RESULTS

Both groups experienced decreases in mean glycosylated hemoglobin after training (AE/RE group: -0.59% [95% confidence interval (CI)=-1.5 to 0.28]; AE group: -0.31% [95% CI=-0.60 to -0.03]), with no significant between-group differences. There was an interaction between group and time with respect to change in thigh lean tissue cross-sectional area, with the AE/RE group gaining more lean tissue (AE/RE group: 15.1 cm(2) [95% CI=7.6 to 22.5]; AE group: -5.6 cm(2) [95% CI=-10.4 to 0.76]). Both groups experienced decreases in mean thigh IMF cross-sectional area (AE/RE group: -1.2 cm(2) [95% CI=-2.6 to 0.26]; AE group: -2.2 cm(2) [95% CI=-3.5 to -0.84]) and increases in 6-minute walk distance (AE/RE group: 45.5 m [95% CI=7.5 to 83.6]; AE group: 29.9 m [95% CI=-7.7 to 67.5]) after training, with no between-group differences. There was an interaction between group and time with respect to change in BMI, with the AE/RE group experiencing a greater decrease in BMI.

DISCUSSION AND CONCLUSION

Significant improvements in long-term glycemic control, thigh composition, and physical performance were demonstrated in both groups after participating in a 16-week exercise program.

SUBJECTS

in the AE/RE group demonstrated additional improvements in thigh lean tissue and BMI. Improvements in thigh lean tissue may be important in this population as a means to increase resting metabolic rate, protein reserve, exercise tolerance, and functional mobility.

Synthesis and evaluation of globular Gd-DOTA-monoamide conjugates with precisely controlled nanosizes for magnetic resonance angiography

The purpose of this study was to design and prepare macromolecular contrast agents (CAs) with a precisely defined globular structure for MR angiography and tumor angiogenesis imaging. Generations 1 through 3 (Gd-DOTA-monoamide)-poly-L-lysine octasilsesquioxane dendrimers were prepared as nanoglobular MRI CAs. The nanoglobular Gd(III) chelates had a well-defined compact globular structure and high loading of Gd-DOTA-monoamide at their surface. The size of the G1, G2, and G3 nanoglobular MRI CAs was approximately 2.0, 2.4, and 3.2 nm, respectively. The T1 relaxivity of G1, G2, and G3 nanoglobular MRI CAs was approximately 6.4, 7.2, and 10.0 mM(-1) sec(-1) at 3T, respectively. The nanoglobular MRI CAs showed size-dependent contrast enhancement within the mouse vasculature, which gradually decayed to baseline after a 60 min session. The G3 nanoglobular CA resulted in more significant and prolonged vascular enhancement than the smaller nanoglobular agents at 0.03 mmol Gd/kg. The G3 agent also provided significant and prolonged contrast enhancement in the heart and vasculature at a dose as low as 0.01 mmol Gd/kg, 1/10th of the regular clinical dose. Significant enhancement was observed in tumor for all CAs. The nanoglobular CAs cleared via renal filtration and accumulated in the urinary bladder as shown in the dynamic MR images. The nanoglobular Gd(III) chelates are effective intravascular MRI CAs at substantially reduced doses. The nanoglobular MRI CAs are promising for further preclinical development for MR angiography and MR imaging of tumor angiogenesis.

A case of broncholithiasis and esophagobronchial fistula

Broncholithiasis is the presence of intrabronchial calcification or ossification. We report a case of broncholiths resulting from extrusion of calcified mediastinal lymph node into a bronchus associated with esophagobronchial fistula that became more symptomatic after bronchoscopic removal of the broncholiths.

A randomized phase 2 trial of combretatstatin A4 phosphate (CA4P) in combination with paclitaxel and carboplatin to evaluate safety and efficacy in subjects with advanced imageable malignancies

14060

Background: CA4P is the lead compound in a class of agents termed Vascular Disrupting Agents. Phase I studies of CA4P demonstrated toxicities that do not overlap those of chemotherapy. In vitro studies show synergistic cytotoxicity for CA4P and chemotherapy. This study was designed to assess safety, toxicity and tumor perfusion of CA4P at 2 doses when combined with paclitaxel and carboplatin at fixed doses. Methods: A one stage, randomized trial for subjects with imageable tumors by DCE-MRI for perfusion. Subjects received either 45 or 63 mg/m2 CA4P IV on Days 1, 8, and 15, then 200 mg/m2 paclitaxel and AUC 6 carboplatin on Day 2 of each 21 day cycle. After completion of 6 cycles, subjects could continue with CA4P alone. DCE-MRI was measured prior and 24 hours after the first dose of CA4P. Results: 13 subjects were accrued from 3/05–11/05. 78 cycles were administered and 1 subject continues active therapy on cycle 19. The median number of cycles administered was 6. Both 45 and 63 CA4P with paclitaxel/carboplatin were well tolerated. The most frequent adverse events are listed in Table 1 . Grade 3–4 AEs were similar between the two dose groups. Table 1 : Most Frequent AEs by CA4P Dose DCE-MRI data showed a mean reduction in blood flow for both dose groups (46% vs. 19% respectively) confirming CA4P’s tumor vascular disrupting capabilities. Tumor responses were observed and were similar between both dose groups. Best overall response through cycle 6 was 3 PR, and 6 SD. Two subjects with thyroid cancer were randomized to the low dose group and completed cycle 6. The 1st had SD and progressed after cycle 6. The 2nd achieved PR and progressed after 8 cycles. These subjects also had the greatest reduction in tumor blood flow. Ktrans was reduced by 73 and 79% 24 hours post CA4P. Conclusion: These doses of CA4P in combination with paclitaxel and carboplatin were well tolerated, demonstrated anti-tumor activity and reduction of tumor blood flow.

[Table: see text]

No significant financial relationships to disclose.

Neonatal alloimmune thrombocytopenia with significant HLA antibodies

A case of neonatal alloimmune thrombocytopenia (NAIT) secondary to human platelet antigen (HPA)-1a antibodies is reported. Additional multispecific HLA antibodies rendered volunteer donor platelet transfusions ineffective. Despite a high incidence of maternal HLA antibodies in the pregnant population, there is only one previous report of clinically significant HLA antibodies.

Effect of structured preoperative teaching on anxiety levels of patients scheduled for cataract surgery

Cataract surgery is an outpatient, fast-paced surgical intervention that requires preoperative patient education to ensure success. The purpose of this study was to determine the effect of structured preoperative instructions on anxiety levels of patients scheduled for cataract surgery. A pretest/posttest classical experimental design was used to test the hypothesis. Anxiety was assessed by using the Spielberger State-Trait Anxiety Inventory. Blood pressure, pulse, and respiration were measured to assess the stimulation of the sympathetic nervous system in response to stress. The findings of this study support the hypothesis that structured preoperative instructions will decrease the anxiety level of patients scheduled for cataract surgery.

A study: will waiting room time be reduced when the redesigned preliminary workup is performed by a certified ophthalmic technician?

The primary source of patient dissatisfaction in ophthalmic clinics is waiting room time. At one clinic, a study was conducted to determine whether redesignating preliminary workup tasks affected waiting room time. Previously, technicians and the ophthalmic registered nurse performed workups by taking histories, checking vision, reading glasses, performing refractions, conducting tonometry and slit lamp examinations, and dilating patients' eyes. Because the technicians' refractions were often inaccurate, the nurse or the doctor had to redo the refraction, prolonging waiting room times. Workup tasks, beginning with refractions, were transferred from the technicians to the nurse, which increased patient satisfaction and staff efficiency.

Identification of an HLA-A11 serological variant and its characterization by sequencing based typing

We have identified an HLA-A11 variant allele, A*1105, segregating in a Caucasoid family. The variant antigen expressed by this allele failed to cross-react with most Caucasoid anti-HLA-A11 antisera tested. Sequencing based typing has been used to characterize this new allele and this showed that it has a novel mutation at a polymorphic position (502) in exon 3. In comparison with A*1101, the mutation (A-->G) results in an amino acid change from positively-charged lysine to negative glutamate and this may explain the altered HLA-A11 serological profile exhibited by this antigen. The new allele was found in a patient with acute lymphoid leukaemia (ALL), her father and two siblings.

Dynamic shimming for multi-slice magnetic resonance imaging

Dynamic shimming has been implemented in three pulse sequences on a commercial GE Signa 1.5-T imaging system. Multi-slice field maps are acquired before the imaging sequence, and linear shim terms and center frequencies are calculated for each slice. During the imaging scan, the linear shim terms and center frequency are set before each pulse sequence repetition according to the current slice. Acquisition of multi-slice field maps and calculation of shim terms and center frequency for each slice are accomplished in a matter of seconds. Pulse sequences require only minimal modification to add dynamic shimming capability. Results are shown for a fat saturation spin-echo sequence, a single-shot echo-planar gradient-recalled echo sequence, and a spiral acquisition gradient-recalled echo sequence. In all cases, dynamic shimming with shim currents and center frequency optimized for each slice is shown to give better results than constant shim currents and a single center frequency optimized for the entire volume of interest.

Three-dimensional spectral-spatial excitation

A method of three-dimensional spectral-spatial excitation is presented which is selective simultaneously in two spatial dimensions and in the spectral or chemical shift dimension. This method can be used to create spectral passbands whose center frequency varies as a function of spatial location within an imaging plane. This variation of passband center frequency may be specified by an acquired main field (B0) map; the resulting excitations compensate for inhomogeneity of the B0 field. In vivo images are presented in which three-dimensional spectral-spatial excitation allows selective water-only imaging in the presence of large B0 inhomogeneity where conventional spectrally selective imaging falls. Phantom studies give a detailed profile of the performance of three-dimensional spectral-spatial pulses suitable for water-only or fat-saturation imaging. These pulses may also be useful for fat and water suppression in spectroscopic imaging. Performance constraints imposed by limited gradient slew rates are analyzed and quantified.

Infantile osteopetrosis; bone marrow transplantation from a cousin donor

The successful correction of infantile osteopetrosis in an Asian child by bone marrow transplantation (BMT) from an HLA-A,B matched cousin donor is reported. Retrospective HLA molecular analysis revealed that patient and donor were incompatible for HLA-DPB1. Donor type cells detected in the patient after transplantation indicate successful engraftment. The patient is currently alive and well.

Immunoradiometric assay for cytomegalovirus-specific IgG antibodies: assay development and evaluation in blood transfusion practice

An immunoradiometric assay (radio-immunosorbent test; RIST) for the detection of IgG antibodies to human herpesvirus 4 [human cytomegalovirus (CMV)] has been developed. The technique utilizes CMV antigen passively adsorbed to a polyvinyl microtitration plate and a radiolabelled murine monoclonal anti-human IgG antibody to detect binding of human antibody to the 'solid phase' reagent. The assay was optimized, and its specificity confirmed by testing paired acute and convalescent sera from patients with acute CMV or other human herpesvirus infections. To determine the assay's sensitivity 1433 blood donor sera were examined. The RIST was more sensitive than a standard complement fixation (CFT), in that 53% of these sera were positive by RIST and 48% positive by CFT. There were 1303 concordant results, 88 sera positive only by RIST and 19 sera were only positive by CFT. These discrepant results remained after an attempt to exclude false positive reactivity; their significance is discussed. Use of a monoclonal anti-human IgG antibody in the RIST reduced non-specific binding to the control uninfected cell antigen such that blood donor sera could be tested in the assay using only a CMV antigen without generating an unacceptable false positive rate.

An HLA-DR negative acute leukaemia which stimulates MLC and CMC responses

We describe an acute myelomonocytic leukaemia (E72) devoid of cell-surface HLA-DR antigens, but capable of inducing cellular responses. Leukaemia E72 induced proliferation of normal lymphocytes in primary mixed lymphocyte culture (MLC), which was only weakly inhibited by anti-DR sera. Depletion of a small percentage (congruent to 4%) of DR+ cells on a cell-sorter failed to abrogate the capacity of E72 to stimulate MLC and cell-mediated cytotoxicity (CMC) responses. We found that normal lymphocytes primed with E72 responded in secondary MLC to lymphocytes and leukaemias, suggesting that the lymphocyte-activating determinant (LAD) on E72 is not leukaemia-specific. In addition, E72 induced CMC responses to both leukaemias and lymphocytes. We suggest that E72 may express a novel HLA or non-HLA LAD.

Rapid micromethod for blood lead analysis by anodic stripping voltammetry

We describe a rapid microscale procedure for blood lead determination by anodic stripping voltammetry. Results correlate well with those obtained by atomic absorption spectroscopy. The procedure involves use of a metal-exchange reagent, which rapidly releases bound lead from its macromolecular binding sites, thus eliminating a long and cumbersome perchloric acid digestion procedure. Reproducibility and analytical recovery of added lead were both excellent. Our results show that anodic stripping voltammetry is a reliable, sensitive micromethod for routine determination of blood lead.

Rapid micromethod for blood lead analysis by anodic stripping voltammetry

We describe a rapid microscale procedure for blood lead determination by anodic stripping voltammetry. Results correlate well with those obtained by atomic absorption spectroscopy. The procedure involves use of a metal-exchange reagent, which rapidly releases bound lead from its macromolecular binding sites, thus eliminating a long and cumbersome perchloric acid digestion procedure. Reproducibility and analytical recovery of added lead were both excellent. Our results show that anodic stripping voltammetry is a reliable, sensitive micromethod for routine determination of blood lead.