Masoom A Haider

University of Toronto, Toronto, Ontario, Canada

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Publications (197)506.85 Total impact

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    ABSTRACT: Purpose To determine if the integration of diagnostic magnetic resonance (MR) imaging and MR-guided biopsy would improve target delineation for focal salvage therapy in men with prostate cancer. Materials and Methods Between September 2008 and March 2011, 30 men with biochemical failure after radiation therapy for prostate cancer provided written informed consent and were enrolled in a prospective clinical trial approved by the institutional research ethics board. An integrated diagnostic MR imaging and interventional biopsy procedure was performed with a 1.5-T MR imager by using a prototype table and stereotactic transperineal template. Multiparametric MR imaging (T2-weighted, dynamic contrast material-enhanced, and diffusion-weighted sequences) was followed by targeted biopsy of suspicious regions and systematic sextant sampling. Biopsy needle locations were imaged and registered to diagnostic images. Two observers blinded to clinical data and the results of prior imaging studies delineated tumor boundaries. Area under the receiver operating characteristic curve (Az) was calculated based on generalized linear models by using biopsy as the reference standard to distinguish benign from malignant lesions. Results Twenty-eight patients were analyzed. Most patients (n = 22) had local recurrence, with 82% (18 of 22) having unifocal disease. When multiparametric volumes from two observers were combined, it increased the apparent overall tumor volume by 30%; however, volumes remained small (mean, 2.9 mL; range, 0.5-8.3 mL). Tumor target boundaries differed between T2-weighted, dynamic contrast-enhanced, and diffusion-weighted sequences (mean Dice coefficient, 0.13-0.35). Diagnostic accuracy in the identification of tumors improved with a multiparametric approach versus a strictly T2-weighted or dynamic contrast-enhanced approach through an improvement in sensitivity (observer 1, 0.65 vs 0.35 and 0.44, respectively; observer 2, 0.82 vs 0.64 and 0.53, respectively; P < .05) and improved further with a 5-mm expansion margin (Az = 0.85 vs 0.91 for observer 2). After excluding three patients with fewer than six informative biopsy cores and six patients with inadequately stained margins, MR-guided biopsy enabled more accurate delineation of the tumor target volume be means of exclusion of false-positive results in 26% (five of 19 patients), false-negative results in 11% (two of 19 patients) and by guiding extension of tumor boundaries in 16% (three of 19 patients). Conclusion The integration of guided biopsy with diagnostic MR imaging is feasible and alters delineation of the tumor target boundary in a substantial proportion of patients considering focal salvage. © RSNA, 2014 Online supplemental material is available for this article.
    Radiology 09/2014; · 6.34 Impact Factor
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    ABSTRACT: The clinical use of conventional ultrasonography (US) in autosomal dominant polycystic kidney disease (ADPKD) is currently limited by reduced diagnostic sensitivity, especially in at-risk subjects younger than 30 years of age. In this single-center prospective study, we compared the diagnostic performance of MRI with that of high-resolution (HR) US in 126 subjects ages 16-40 years born with a 50% risk of ADPKD who underwent both these renal imaging studies and comprehensive PKD1 and PKD2 mutation screening. Concurrently, 45 healthy control subjects without a family history of ADPKD completed the same imaging protocol. We analyzed 110 at-risk subjects whose disease status was unequivocally defined by molecular testing and 45 unaffected healthy control subjects. Using a total of >10 cysts as a test criterion in subjects younger than 30 years of age, we found that MRI provided both a sensitivity and specificity of 100%. Comparison of our results from HR US with those from a previous study of conventional US using the test criterion of a total of three or more cysts found a higher diagnostic sensitivity (approximately 97% versus approximately 82%) with a slightly decreased specificity (approximately 98% versus 100%) in this study. Similar results were obtained in test subjects between the ages of 30 and 40 years old. These results suggest that MRI is highly sensitive and specific for diagnosis of ADPKD. HR US has the potential to rival the diagnostic performance of MRI but is both center- and operator-dependent.
    Journal of the American Society of Nephrology : JASN. 07/2014;
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    ABSTRACT: In active surveillance (AS) patients: (i) To compare the ability of a multiparametric MRI (mpMRI)-ultrasound biopsy system to detect clinically significant (CS) prostate cancer with systematic 12-core biopsy (R-TRUSBx), and (ii) To assess the predictive value of mpMRI with biopsy as the reference standard.
    Journal of Magnetic Resonance Imaging 07/2014; · 2.57 Impact Factor
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    ABSTRACT: Patients with colorectal cancer with liver metastases undergo hepatic resection with curative intent. Positron emission tomography combined with computed tomography (PET-CT) could help avoid noncurative surgery by identifying patients with occult metastases. To determine the effect of preoperative PET-CT vs no PET-CT (control) on the surgical management of patients with resectable metastases and to investigate the effect of PET-CT on survival and the association between the standardized uptake value (ratio of tissue radioactivity to injected radioactivity adjusted by weight) and survival. A randomized trial of patients older than 18 years with colorectal cancer treated by surgery, with resectable metastases based on CT scans of the chest, abdomen, and pelvis within the previous 30 days, and with a clear colonoscopy within the previous 18 months was conducted between 2005 and 2013, involving 21 surgeons at 9 hospitals in Ontario, Canada, with PET-CT scanners at 5 academic institutions. Patients were randomized using a 2 to 1 ratio to PET-CT or control. The primary outcome was a change in surgical management defined as canceled hepatic surgery, more extensive hepatic surgery, or additional organ surgery based on the PET-CT. Survival was a secondary outcome. Of the 263 patients who underwent PET-CT, 21 had a change in surgical management (8.0%; 95% CI, 5.0%-11.9%). Specifically, 7 patients (2.7%) did not undergo laparotomy, 4 (1.5%) had more extensive hepatic surgery, 9 (3.4%) had additional organ surgery (8 of whom had hepatic resection), and the abdominal cavity was opened in 1 patient but hepatic surgery was not performed and the cavity was closed. Liver resection was performed in 91% of patients in the PET-CT group and 92% of the control group. After a median follow-up of 36 months, the estimated mortality rate was 11.13 (95% CI, 8.95-13.68) events/1000 person-months for the PET-CT group and 12.71 (95% CI, 9.40-16.80) events/1000 person-months for the control group. Survival did not differ between the 2 groups (hazard ratio, 0.86 [95% CI, 0.60-1.21]; P = .38). The standardized uptake value was associated with survival (hazard ratio, 1.11 [90% CI, 1.07-1.15] per unit increase; P < .001). The C statistic for the model including the standardized uptake value was 0.62 (95% CI, 0.56-0.68) and without it was 0.50 (95% CI, 0.44-0.56). The difference in C statistics is 0.12 (95% CI, 0.04-0.21). The low C statistic suggests that the standard uptake value is not a strong predictor of overall survival. Among patients with potentially resectable hepatic metastases of colorectal adenocarcinoma, the use of PET-CT compared with CT alone did not result in frequent change in surgical management. These findings raise questions about the value of PET-CT scans in this setting. Identifier: NCT00265356.
    JAMA The Journal of the American Medical Association 05/2014; 311(18):1863-9. · 29.98 Impact Factor
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    ABSTRACT: Purpose To prospectively compare image quality with use of a two-channel solid reusable phased-array endorectal receiver coil (SPAC) with that of the single-channel inflatable endorectal balloon coil currently in widespread use for 1.5-T magnetic resonance (MR) imaging of the prostate. Materials and Methods Institutional review board approval and informed consent were obtained. Multiparametric prostate MR imaging at 1.5 T was performed in patients who were suspected of having cancer. Thirty consecutive patients were included (mean age, 66.1 years; range, 49-76 years). The first 15 patients were imaged by using a balloon coil and an eight-channel external array, and the remaining 15 were imaged with a SPAC alone. One patient was imaged with both techniques. Axial T2-weighted images acquired at both standard and high spatial resolution were used to compare image quality between coils. Qualitative assessments of image quality were made separately by three radiologists. Signal-to-noise ratio (SNR) profiles were determined on a pixel-by-pixel basis in a 1-cm central band in the prostate by using T1-weighted axial images at the apex, midgland, and base. Interrater reliability was determined by using a two-way intraclass correlation coefficient, qualitative scores were compared by using the Student t test for independent samples, and SNR profiles were plotted by using a Biot-Savart curve approximation. Results SNR of the SPAC was significantly better compared with that of the balloon coil at distances up to 3.0 cm at the apex and 3.5 cm at the base and midgland (P < .001). There was a 7% improvement in SNR at the mean maximal anteroposterior prostate dimension in this cohort and a 96% improvement at half this distance. At both standard and high spatial resolution, significant improvements in overall image quality (P = .015 and P < .001, respectively), visibility of the anterior gland (P = .009 and P < .001, respectively), and noise (P < .001 and P < .001, respectively) were seen when the SPAC was used. Interrater reliability was 0.536 (95% confidence interval: 0.461, 0.603). Conclusion Both SNR and image quality were significantly improved with use of the SPAC at 1.5 T compared with use of the single-channel inflatable endorectal balloon coil. © RSNA, 2013.
    Radiology 02/2014; 270(2):556-65. · 6.34 Impact Factor
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    ABSTRACT: Purpose: To study the effect of needle placement uncertainty on the expected probability of achieving complete focal target destruction in focal laser ablation (FLA) of prostate cancer.Methods: Using a simplified model of prostate cancer focal target, and focal laser ablation region shapes, Monte Carlo simulations of needle placement error were performed to estimate the probability of completely ablating a region of target tissue.Results: Graphs of the probability of complete focal target ablation are presented over clinically relevant ranges of focal target sizes and shapes, ablation region sizes, and levels of needle placement uncertainty. In addition, a table is provided for estimating the maximum target size that is treatable. The results predict that targets whose length is at least 5 mm smaller than the diameter of each ablation region can be confidently ablated using, at most, four laser fibers if the standard deviation in each component of needle placement error is less than 3 mm. However, targets larger than this (i.e., near to or exceeding the diameter of each ablation region) require more careful planning. This process is facilitated by using the table provided.Conclusions: The probability of completely ablating a focal target using FLA is sensitive to the level of needle placement uncertainty, especially as the target length approaches and becomes greater than the diameter of ablated tissue that each individual laser fiber can achieve. The results of this work can be used to help determine individual patient eligibility for prostate FLA, to guide the planning of prostate FLA, and to quantify the clinical benefit of using advanced systems for accurate needle delivery for this treatment modality.
    Medical Physics 01/2014; 41(1):013301. · 2.91 Impact Factor
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    ABSTRACT: Most small renal masses (SRMs) are diagnosed incidentally and have a low malignant potential. As more elderly patients and infirm patients are diagnosed with SRMs, there is an increased interest in active surveillance (AS) with delayed intervention. Patient and tumour characteristics relating to aggressive disease have not been well-studied. The objective was to determine predictors of growth of SRMs treated with AS. A multicentre prospective phase 2 clinical trial was conducted on 207 SRMs in 169 patients in 8 institutions in Canada from 2004 to 2009; in these patients treatment was delayed until disease progression. Patient and tumour characteristics were evaluated to determine predictors of growth of SRMs by measuring rates of change in growth (on imaging) over time. All patients underwent AS for presumed renal cell carcinoma (RCC) based on diagnostic imaging. We used the following factors to develop a predictive model of tumour growth with binary recursive partitioning analysis: patient characteristics (age, symptoms at diagnosis) and tumour characteristics (consistency [solid vs. cystic] and maximum diameter at diagnosis. With a median follow-up of 603 days, 169 patients (with 207 SRMs) were followed prospectively. Age, symptoms at diagnosis, tumour consistency and maximum diameter of the renal mass were not predictors of growth. This cohort was limited by lack of availability of patient and tumour characteristics, such as sex, degree of endophytic component and tumour location. Slow growth rates and the low malignant potential of SRMs have led to AS as a treatment option in the elderly and infirm population. In a large prospective cohort, we have shown that age, symptoms, tumour consistency and maximum diameter of the mass at diagnosis are not predictors of growth of T1a lesions. More knowledge on predictors of growth of SRMs is needed.
    Canadian Urological Association journal = Journal de l'Association des urologues du Canada 01/2014; 8(1-2):24-7. · 1.66 Impact Factor
  • Masoom A. Haider
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    ABSTRACT: LEARNING OBJECTIVES 1) To be able to perform an MRI protocol for evalaution of pancreatic cystic lesions. 2) To recognize the classic MRI findings for cystic pathologies of the pancreas. 3) To have a pragmatic approach to management reccomendations of cystic lesions of the pancreas. ABSTRACT With the widespread use of cross sectional imaging cystic pancreatic lesions are being detected with increasing frequency. The dominance of pseudocyst as the commonest type of pancreatic cyst may no longer hold. Radiologists must be familiar with the features of cystic neoplasms. MRI offers excellent tissue contrast for characterization of pancreatic cysts as well as for assessment of relationship to the pancreatic duct which can be helpful for differential diagnosis. A number of MRI features can be used to help guide management and offer likely differential diagnosis and will be presented. At the same time MRI has resulted in increased detection of tiny incidental simple pancreatic cysts for which limited or no followup may be necessary. It is important to recognize that in some cases MRI and other non-invasive imaging methods cannot provide reliable diagnosis as there is substantial overlap in imaging findings between some benign and pre-malignant or malignant cystic neoplasm. These scenarios will be reviewed.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
  • Katherine Zukotynski, Masoom A Haider
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    ABSTRACT: Imaging plays a central role in the detection, diagnosis, staging, and follow-up of prostate carcinoma. This article discusses the role of multiple imaging modalities in the diagnosis and staging of prostate cancer, with attention to imaging features of localized and metastatic disease, imaging adjuncts to improve prostate biopsy, and potential imaging biomarkers. In addition, the role of imaging in the management of prostate cancer, with emphasis on surveillance, evaluation of response to new therapies, and detection of recurrent disease is described. Lastly, future directions in prostate cancer imaging are presented.
    Hematology/oncology clinics of North America 12/2013; 27(6):1163-87. · 2.05 Impact Factor
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    ABSTRACT: OBJECTIVE. The purpose of this article is to review the many evolving facets of MRI in the evaluation of prostate cancer. We will discuss the roles of multiparametric MRI, including diffusion-weighted MRI, dynamic contrast-enhanced MRI, and MR spectroscopy, as adjuncts to morphologic T2-weighted imaging in detection, staging, treatment planning, and surveillance of prostate cancer. CONCLUSION. Radiologists need to understand the advantages, limitations, and potential pitfalls of the different sequences to provide optimal assessment of prostate cancer.
    American Journal of Roentgenology 12/2013; 201(6):1229-1238. · 2.90 Impact Factor
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    ABSTRACT: To determine whether R2* values are a consistent predictor of hepatic iron concentration (HIC) in thalassemia patients by demonstrating a correlation between R2* relaxation rates and FerriScan-determined HIC. Eighty-eight patients with thalassemia major were retrospectively evaluated. All patients underwent FerriScan imaging and multiecho gradient echo imaging. The results from FerriScan analysis were fitted against R2* estimates using linear regression. There was a very strong linear correlation between R2* values and FerriScan-determined HIC (Spearman correlation of 0.976; 95% confidence interval [CI]: 0.963, 0.984). R2* values can predict HIC determined by FerriScan using a linear calibration curve. This technique may provide a potentially cost-saving alternative for hepatic iron determination and improve acceptance by referring physicians.J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 10/2013; · 2.57 Impact Factor
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    ABSTRACT: A critical requirement of MR-guided interventions is the visualization of an instrument (e.g., catheter, needle) during the procedure. One approach is to fill the instrument with a contrast agent. Previously, the optimization of contrast agent visualization was performed only empirically. In the present study, an analytic optimization of contrast agent SNR efficiency was performed for a spoiled gradient echo pulse sequence. Optimal flip angle, repetition time, echo time, and contrast agent concentration were derived analytically. The solution is valid for any contrast agent, provided the relationship between T1 , T2 , and doping concentration is known. Phantom experiments validated the analytic optimization for Gd- and MnCl2 -based contrast agents. Results showed excellent agreement between experimentally predicted and theoretically observed magnetization behavior. In vivo experiments demonstrated optimized contrast agent visualization in brain, heart, and prostate applications. The results demonstrated the large SNR that can be achieved with analytic optimization. As a practical guideline, an 11% dilution of 500 mMol/L Gd-DTPA solution, repetition time ≈ 4 ms, echo time ≈ 1 ms, and θ ≈ 65° was found to provide a large SNR. This study derived and validated a method for analytically optimizing contrast agent SNR efficiency. This information may be useful for visualizing instruments during MR-guided interventions. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 06/2013; · 3.27 Impact Factor
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    ABSTRACT: Dominant cancer foci within the prostate are associated with sites of local recurrence post radiotherapy. In this systematic review we sought to address the question: "what is the clinical evidence to support differential boosting to an imaging defined GTV volume within the prostate when delivered by external beam or brachytherapy". A systematic review was conducted to identify clinical series reporting the use of radiation boosts to imaging defined GTVs. Thirteen papers describing 11 unique patient series and 833 patients in total were identified. Methods and details of GTV definition and treatment varied substantially between series. GTV boosts were on average 8Gy (range 3-35Gy) for external beam, or 150% for brachytherapy (range 130-155%) and GTV volumes were small (<10ml). Reported toxicity rates were low and may reflect the modest boost doses, small volumes and conservative DVH constraints employed in most studies. Variability in patient populations, study methodologies and outcomes reporting precluded conclusions regarding efficacy. Despite a large cohort of patients treated differential boosts to imaging defined intra-prostatic targets, conclusions regarding optimal techniques and/or efficacy of this approach are elusive, and this approach cannot be considered standard of care. There is a need to build consensus and evidence. Ongoing prospective randomized trials are underway and will help to better define the role of differential prostate boosts based on imaging defined GTVs.
    Radiotherapy and Oncology 06/2013; · 4.52 Impact Factor
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    ABSTRACT: This work is to compare the kinetic parameters derived from the DCE-CT and -MR data of a group of 37 patients with cervical cancer. The modified Tofts model and the reference tissue method were applied to estimate kinetic parameters. In the MR kinetic analyses using the modified Tofts model for each patient data set, both the arterial input function (AIF) measured from DCE-MR images and a population-averaged AIF from the literature were applied to the analyses, while the measured AIF was used for the CT kinetic analysis. The kinetic parameters obtained from both modalities were compared. Significant moderate correlations were found in modified Tofts parameters [volume transfer constant(K(trans) ) and rate constant (k(ep) )] between CT and MR analysis for MR with the measured AIFs (R = 0·45, P<0·01 and R = 0·40, P<0·01 in high-K(trans) region; R = 0·38, P<0·01 and R = 0·80, P<0·01 in low-K(trans) region) as well as with the population-averaged AIF (R = 0·59, P<0·01 and R = 0·62, P<0·01 in high-K(trans) region; R = 0·50, P<0·01 and R = 0·63, P<0·01 in low-K(trans) region), respectively. In addition, from the Bland-Altman plot analysis, it was found that the systematic biases (the mean difference) between the modalities were drastically reduced in magnitude by adopting the population-averaged AIF for the MR analysis instead of the measured ones (from 51·5% to 18·9% for K(trans) and from 21·7% to 4·1% for k(ep) in high-K(trans) region; from 73·0% to 29·4% for K(trans) and from 63·4% to 24·5% for k(ep) in low-K(trans) region). The preliminary results showed the feasibility in the interchangeable use of the two imaging modalities in assessing cervical cancers.
    Clinical Physiology and Functional Imaging 03/2013; 33(2):150-61. · 1.33 Impact Factor
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    ABSTRACT: PURPOSE: To investigate the spatial, temporal, and temperature resolution of a segmented gradient echo echo-planar imaging (EPI) technique as applied to proton resonance frequency (PRF) shift thermometry at 3 T in the human prostate gland, and to determine appropriate sequence parameters for magnetic resonance imaging (MRI)-controlled transurethral ultrasound thermal therapy. MATERIALS AND METHODS: Eleven healthy volunteers (age range 23-58) were scanned at 3 T with a 16-channel torso coil to study the behavior of a gradient echo EPI thermometry sequence. The temperature stability and geometric distortion were assessed for 11 different parameter sets. In a further five volunteers, the prostate T2* was measured. RESULTS: For all scan parameters investigated, the temperature standard deviation within the prostate was less than 1°C, while the distortion was less than 1 mm. Temperature stability was best with higher TE values (up to 25 msec), larger voxel sizes and lower EPI factors, but this had to be balanced against requirements for good spatial and temporal resolution. Prostate T2* values ranged from 30-50 msec. CONCLUSION: A good balance between temperature stability and temporal/spatial resolution is obtained with TE = 15 msec, voxel size = 1.14 mm, and EPI factor = 9, resulting in a dynamic scan time of 7.2 seconds for the nine slices. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 02/2013; · 2.57 Impact Factor
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    ABSTRACT: PURPOSE: To investigate the tolerability and technical feasibility of performing endorectal MR elastography (eMRE) in human volunteers within the representative age group commonly affected by prostate cancer. MATERIALS AND METHODS: Endorectal MRE was conducted on seven volunteers in a 1.5 Tesla (T) MR imager using a rigid endorectal coil. Another five volunteers were imaged on a 3T MR imager using an inflatable balloon type endorectal coil. Tolerability was accessed for vibration amplitudes of ±1-50 μm and for frequencies of 100-300 Hz. RESULTS: All 12 volunteers tolerated the displacements necessary to successfully perform eMRE. Shear waves with frequencies up to 300 Hz could propagate across the entire prostate using both coil designs. CONCLUSION: The results of this study motivate further investigation of eMRE in prostate cancer patients to help determine if there is an added value of integrating eMRE into existing multi-parametric prostate MRI exams. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 02/2013; · 2.57 Impact Factor
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    ABSTRACT: Background Inhibition of angiogenesis has emerged as an effective therapeutic strategy in metastatic renal cell cancer (mRCC). In this single arm phase 2 study, we evaluated the efficacy and tolerability of cediranib (AZD2171) a potent angiogenesis inhibitor in first line mRCC. Methods Eligible patients who had no prior systemic therapy received cediranib 45 mg orally once daily continuously. The primary endpoint was objective response rate (ORR). Secondary endpoints were clinical benefit rate (ORR plus stable disease (SD) ≥ 4 months), duration of response, progression free survival (PFS), median overall survival (OS), safety and tolerability. Results Between January 2006 and April 2008, 44 patients were accrued. The median age was 62 (range 44-83) and performance status was either 0 (22 patients) or 1 (22 patients). Of the 39 evaluable patients there were 15 (38 %) partial responses (95 % CI: 23-55 %); 18 stable disease (SD) for a clinical benefit rate of 33/39 = 85 % (95 % CI: 69-94 %) and 6 progressive disease. Median PFS was 8.9 months (95 % CI: 5.1-12.9); and median OS was 28.6 months (95 % CI: 18.2-37.3 months). The most frequent grade 3 or higher AEs included hypertension, fatigue, hand-foot syndrome and diarrhea. Conclusions Cediranib demonstrated significant anti-tumour activity in first line, treatment-naive mRCC, with efficacy parameters comparable to the other approved agents (sunitinib and pazopanib) in this setting. The main toxicities were fatigue, diarrhea and hypertension. Based on these encouraging results, further evaluation of cediranib in mRCC at a more tolerable dose of 30 mg daily appears warranted.
    Investigational New Drugs 01/2013; · 3.50 Impact Factor
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    ABSTRACT: PURPOSE: To evaluate a magnetic resonance (MR)/ultrasound (US) coregistration system with US used in follow-up diagnostic studies of lesions originally identified by MR imaging. MATERIALS AND METHODS: A single-center prospective study enrolled 21 consecutive patients (age, 64.0 y±7.5; eight men [age, 63.0 y±7.1] and 13 women [age, 65.0 y±7.3]) evaluated for potential surgical resection of liver metastases. Each patient underwent same-day MR examination and two US examinations: one regular and one with the MR/US coregistration system. Target lesions were identified on MR imaging, and US was used in follow-up diagnostic studies of lesions originally identified by MR imaging. During US, two outcome measures (target localization success and target localization time) were collected. Ratios of lesions found per patient were compared with a paired Wilcoxon test, and a Student t test was used to compare target localization time. RESULTS: Ratios of lesions found per patient with the coregistered system (93.7%) and conventional US (73.3%) were statistically different (P =.003). Lesions found by the coregistration system but not conventional US were statistically smaller than those found by both systems (6.1 mm±4.0 vs 15.6 mm±9.8; P<.0006). There was no statistical difference in target localization time for detection of lesions found by coregistered (100 s±89) and conventional US (108 s±86; P = .78). CONCLUSIONS: The MR/US coregistration system increases the number of lesions detected with US versus standard US alone. This may prove beneficial in surgical and nonsurgical management of patients with focal liver lesions.
    Journal of vascular and interventional radiology: JVIR 01/2013; · 1.81 Impact Factor
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    ABSTRACT: Purpose To characterize nonrespiratory stomach motion in the fasting state and postprandial. Methods and materials Ten healthy volunteers underwent 2-dimensional Fiesta cine magnetic resonance imaging studies in 30-second voluntary breath hold, in axial, coronal, and 2 oblique planes while fasting, and 5, 15, 30, 45, and 60 minutes postmeal. Each stomach contour was delineated and sampled with 200 points. Matching points were found for all contours in the same 30-second acquisition. Using deformable parametric analysis (Matlab, version 7.1), mean magnitude, and standard deviation of displacement of each point were determined for each patient. Maximal, minimal, and median population values in 6 cardinal, and in any direction, were calculated. Results The median of mean displacements for the baseline position of each point was small and rarely exceeded 1.1 mm; greatest value was 1.6 mm superior–inferior. Median displacement (pooled across time) in the right–left, superior–inferior, and anterior–posterior directions was 0.3 (range, − 0.7 to 1.3), 0.8 (− 0.4 to 2.4), and 0.3 (− 1.1 to 1.6) mm, respectively. Fasting and postprandial standard deviation did not differ. Conclusions Nonrespiratory stomach displacement is small and stomach position is stable after a small, standard meal. Radiation therapy may be delivered at any time within the first hour after eating without significant compromise of planned planning target volumes.
    Practical Radiation Oncology. 01/2013;
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    ABSTRACT: The treatment of low-risk prostate cancer is a common clinical dilemma between standard curative whole gland therapy (and its associated quality of life diminishing side effects) and active surveillance (and its low, but real, risk of progression). The goal of focal therapy in low-risk prostate cancer is to achieve the best balance between cancer control and maintenance of quality of life. Magnetic resonance-guided focused ultrasound (MRgFUS) surgery is a non-invasive thermal ablation method that integrates magnetic resonance imaging for target identification, treatment planning and closed-loop control of thermal deposition and focused ultrasound for thermal ablation of the tumour target. This novel transrectal system allows for tumour localization, targeting and monitoring of tumour target ablation in real time, while simultaneously preserving adjacent normal tissue thereby minimizing the side effects of standard curative surgical or radiation therapy. We report the first North American clinical experience of treatment of localized prostate cancer with focal MR-guided transrectal focused ultrasound ( identifier NCT01226576).
    Canadian Urological Association journal = Journal de l'Association des urologues du Canada 12/2012; 6(6):E283-6. · 1.66 Impact Factor

Publication Stats

3k Citations
506.85 Total Impact Points


  • 2001–2014
    • University of Toronto
      • • Department of Medical Imaging
      • • Department of Radiation Oncology
      • • Faculty of Medicine
      • • Division of General Surgery
      • • Division of Urology
      Toronto, Ontario, Canada
  • 2013
    • Memorial University of Newfoundland
      St. John's, Newfoundland and Labrador, Canada
    • The University of Western Ontario
      London, Ontario, Canada
  • 2005–2013
    • University Health Network
      • • Department of Medical Imaging
      • • Radiation Medicine Program
      Toronto, Ontario, Canada
  • 2011
    • St. Michael's Hospital
      Toronto, Ontario, Canada
  • 2002–2011
    • Mount Sinai Hospital, Toronto
      • Department of Medical Imaging
      Toronto, Ontario, Canada
  • 2001–2011
    • The Princess Margaret Hospital
      Toronto, Ontario, Canada
  • 2010
    • Mount Sinai Hospital
      New York City, New York, United States
    • University of Chicago
      • Department of Medicine
      Chicago, IL, United States
  • 2009
    • Illinois Institute of Technology
      • Department of Electrical & Computer Engineering
      Chicago, IL, United States
    • University of Oxford
      • Gray Institute for Radiation Oncology and Biology
      Oxford, ENG, United Kingdom