Alison Harris | UBC - Academia.edu (original) (raw)
Papers by Alison Harris
We would like to thank our printing house Counter Clockwise Design and Production Group for their... more We would like to thank our printing house Counter Clockwise Design and Production Group for their generous support. The UBC Medical Journal uses an open access publishing policy in line with our mandate to publish in a socially responsible way. We endorse open access publishing as the preferred model for scholarly communication and encourage the adoption of open access principles by universities and research agencies. To subscribe, advertise or submit, see our website.
Annals of Hepatology, 2009
Hepatic artery thrombosis (HAT) is relatively infrequent, but possibly a devastating complication... more Hepatic artery thrombosis (HAT) is relatively infrequent, but possibly a devastating complication of orthotopic liver transplantation (OLT). It often requires urgent retransplantation. Two main forms of HAT are recognized as early and late HAT (diagnosis within or after 30 days following LT). Early HAT typically results in graft failure. Late HAT features biliary obstruction, cholangitis, and hepatic abscess formation. We report here the case of a patient of Wilsons disease who presented twelve years post-liver transplant symptoms typical of acute HAT and hepatic infarction. On diagnostic imaging, celiac axis and hepatic artery were thrombosed, resulting in ischemic necrosis of the left hepatic lobe. The resulting sepsis and transient hepatic insufficiency were managed conservatively, and repeat OLT was avoided. The patient remains stable more than one year later. To the best of our knowledge this case report is unique in the literature for the unusually long interval between OLT and late acute HAT, as well as celiac and portal vein occlusion. The acute presentation of sub massive hepatic necrosis is also uncharacteristic of late HAT and more typical of acute HAT. This report describes our experience in managing this and a literature review of the topic.
Radiologic clinics of North America, 2017
Given the high prevalence, increasing incidence, and significant morbidity and mortality related ... more Given the high prevalence, increasing incidence, and significant morbidity and mortality related to hepatocellular carcinoma (HCC), a robust and cost-effective screening and surveillance program is needed. Most societies recommend ultrasound for HCC screening, despite lack of standardization in imaging acquisition, reporting content and language, and follow-up recommendations. The American College of Radiology Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) fills this unmet need by providing standardization in the use of US in at-risk patients. It is anticipated that US LI-RADS will improve the performance of ultrasound for HCC screening and surveillance and unify management recommendations.
International Journal of Surgery Case Reports, 2022
Introduction and importance Although foreign bodies are a rare cause of gastrointestinal tract pe... more Introduction and importance Although foreign bodies are a rare cause of gastrointestinal tract perforation, they may serve as a nidus for hepatic abscess. Abdominal pain is the most common presenting symptom. We present a case of an ingested pen causing duodenal perforation and hepatic abscess several months after initially presenting with a pericardial effusion. Case presentation A 59-year-old female living in an intensive tertiary mental health facility was noted to have an incidental pericardial effusion during work-up for hyponatremia. Seven months later, she developed a new fever and was noted to have interval increase in the pericardial effusion size. This prompted further investigation which finally revealed that an ingested pen had perforated through the first part of the duodenum and caused an abscess in the left lobe of the liver. The pericardial effusion was presumed secondary to local inflammation. Upon discovery of the abscess, the patient underwent successful operative management including abscess drainage, foreign body extraction, and duodenal repair. Clinical discussion Reports of hepatic abscess from foreign body causing duodenal perforation are rare, with bone fragments and toothpicks the most common foreign bodies implicated. There is one other previously reported case of an ingested pen. Abdominal pain is present in up to 85% of cases, but fever may be the only presenting symptom. Conclusion Foreign body migration causing a hepatic abscess may present non-specifically with unexplained fever or even pericardial effusion. Psychiatric comorbidities may contribute to delays in diagnosis due to difficulties recalling the episode of ingestion.
Journal of the American College of Radiology, 2015
The aim of this study was to retrospectively identify trends in the representation of female auth... more The aim of this study was to retrospectively identify trends in the representation of female authorship in prominent general radiology journals over the past 2 decades. Methods: A comprehensive search was conducted for all articles published in 1993, 2003, and 2013 in Radiology, the American Journal of Roentgenology (AJR), European Radiology, and Investigative Radiology. The genders of the first and last authors were collected. Chisquare tests were used for statistical analysis, and P values < .05 were considered to indicate statistical significance. Results: A total of 3,786 articles were reviewed. Overall, women constituted 20.0% authorship, 24.7% of first authors, and 15.2% of senior authors. The average overall female first and senior authorship grew from 19.7% to 32.1% and from 13.6% to 19.1%, respectively from 1993 to 2013. Female first authorship grew over the past 2 decades in the journals reviewed, with significant growth in AJR and Radiology (P < .0001). Female first authorship in the individual journals grew from 16.4%-29.1% in 1993, to 29.1%-34.8% in 2013. Female senior authorship also demonstrated growth in the past 2 decades, growing from 4.3%-17.5% in 1993 to 15.5%-23.2% in 2013. There was significant growth in senior female authorship in Radiology (from 12.1% to 19.2%, P ¼ .004) and European Radiology (from 4.3% to 15.5%, P ¼ .0433). Female senior authorship remained significantly lower than first authorship over the past 2 decades (P ¼ .002, P < .001, and P < .0001). Conclusions: Although women's growth in first authorship in radiology literature is proportional to their growth in the specialty, they continue to remain a minority, especially in senior authorship, and demonstrate similar participation to other medical specialties.
UBC Medical …, 2010
Disease presented to the Emergency Department with abdominal discomfort localized to the left upp... more Disease presented to the Emergency Department with abdominal discomfort localized to the left upper quadrant (LUQ). The discomfort was described as an aching pain of 8/10 severity, periodically radiating to the back. The pain had been present 23 days before ...
Urologia Internationalis, 2011
Objectives: Overdiagnosis is arguably the greatest challenge in the management of men with prosta... more Objectives: Overdiagnosis is arguably the greatest challenge in the management of men with prostate cancer. Multi-parametric (mp)-MRI prior to prostate biopsy may have a role in ruling-in and ruling-out clinically significant disease. Patients and Methods: 114 consecutive men at risk of prostate cancer with previous biopsy underwent mp-MRI prior to transrectal ultrasound (TRUS)-guided biopsies. Standard systematic biopsies were carried out with targeting to suspicious areas. Results: 59.6% had cancer detected by TRUS-guided biopsy. Mean age was 63.6 years (SD 9.0). If men had not been biopsied because of a negative mp-MRI, 21% (24/114) with no cancer and 5% (6/114) with clinically insignificant cancer could have avoided a biopsy. However, 4% (4/114) would have been advised to defer a biopsy that demonstrated the presence of clinically significant cancer. Conclusion: mp-MRI may have a role in ruling-in and ruling-out clinically significant prostate cancer in men at risk prior to biopsy.
Abdominal Radiology, 2021
Purpose This study evaluates the impact of second-opinion review of multiparametric prostate MRI ... more Purpose This study evaluates the impact of second-opinion review of multiparametric prostate MRI for cancer detection by a multidisciplinary review board at a tertiary care center when compared with the initial community radiologist interpretation. Methods Cases were collected retrospectively from multidisciplinary prostate MRI rounds from 2017 to 2020 at a single tertiary care center. Patients with suspected prostate cancer or on active surveillance were referred for consideration of TRUS/ MRI-fusion biopsy based on community-read prostate MRIs. All MRIs were re-read by subspecialized abdominal radiologists and a PI-RADS score assigned. Targeted fusion and 8-12 core systematic biopsy was performed in patients with PIRADS ≥ 3 lesions. Cohen kappa values were used to quantify interobserver agreement. Positive predictive value (PPV) was used to determine accuracy of PI-RADS score for detection of clinically significant prostate cancer (csPCa) (ISUP Grade Group ≥ 2). Results Three hundred and thirty-two lesions in 303 patients were reviewed and 252 lesions in 198 patients biopsied. The PI-RADS score was concordant in 60.5% of lesions, downgraded in 17.8%, and upgraded in 7.8%. Agreement between community and tertiary center interpretation was fair (κ = 0.354), with greater agreement for PI-RADS ≥ 4 (κ = 0.523) than PI-RADS ≥ 3 (κ = 0.456), and peripheral zone (κ = 0.419) than transition zone lesions (κ = 0.251). Prevalence of csPCa in biopsied lesions was 40.9%. Conclusion There is variability in community and tertiary care center interpretation of prostate MRI in cancer detection, with higher concordance rates for higher grade and peripheral zone lesions. These differences demonstrate the added value of multidisciplinary round review and highlight the need for ongoing education and feedback.
Canadian Urological Association journal = Journal de l'Association des urologues du Canada, Jan 6, 2018
The natural history of prostatic lesions identified on multiparametric magnetic resonance imaging... more The natural history of prostatic lesions identified on multiparametric magnetic resonance imaging (mpMRI) is largely unknown. We aimed to describe changes observed over time on serial MRI. All patients with ≥2 MRI studies between 2008 and 2015 at our institution were identified. MRI progression was defined as an increase in Prostate Imaging Reporting and Data System (PI-RADS; version 2) or size of existing lesions, or the appearance of a new lesion PIRADS ≥4. Patients on active surveillance (AS) were analyzed for correlation of MRI progression to biopsy reclassification. A total of 83 patients (54 on AS and 29 for diagnostic purposes) underwent serial MRI, with a mean interval of 1.9 years between scans. At baseline, 115 lesions (66 index, 49 non-index) were identified. Index lesions were more likely than non-index lesions to increase in size ≥2 mm (36.2 vs. 7.3 %; p=0.002). Overall progression was more likely to be seen among the index cohort (34.8 vs. 7.6%; p<0.001). New lesion...
AJR. American journal of roentgenology, Jan 8, 2017
The purpose of this article is to review the general principles, technique, and clinical applicat... more The purpose of this article is to review the general principles, technique, and clinical applications of contrast-enhanced ultrasound of the liver. Proper technique and optimization of contrast-enhanced ultrasound require a balance between maintaining the integrity of the microbubble contrast agent and preserving the ultrasound signal. Established and emerging applications in the liver include diagnosis of focal lesions, aiding ultrasound-guided intervention, monitoring of therapy, and aiding surgical management.
AJR. American journal of roentgenology, Jan 5, 2017
Neurocutaneous syndromes are a heterogeneous group of multisystemic disorders. We review the mult... more Neurocutaneous syndromes are a heterogeneous group of multisystemic disorders. We review the multimodality imaging findings in the disorders with a propensity for intraabdominal disease. We highlight more recently recognized disease patterns and discuss imaging surveillance optimization. Knowledge of varied intraabdominal phenotypic expressions can increase diagnostic rates. Limitation of radiation dose must be considered in screening this tumor-prone population. Early detection of neoplastic findings is critical for morbidity and mortality reduction.
Canadian Association of Radiologists journal = Journal l'Association canadienne des radiologistes, 2017
Magnetic resonance imaging (MRI) has a well-established role as a highly specific and accurate mo... more Magnetic resonance imaging (MRI) has a well-established role as a highly specific and accurate modality for characterizing benign and malignant focal liver lesions. In particular, contrast-enhanced MRI using hepatocyte-specific contrast agents (HSCAs) improves lesion detection and characterization compared to other imaging modalities and MRI techniques. In this pictorial review, the mechanism of action of gadolinium-based MRI contrast agents, with a focus on HSCAs, is described. The clinical indications, protocols, and emerging uses of the 2 commercially available combined contrast agents available in the United States, gadoxetate disodium and gadobenate dimeglumine, are discussed. The MRI features of these agents are compared with examples of focal hepatic masses, many of which have been obtained within the same patient therefore allowing direct lesion comparison. Finally, the pitfalls in the use of combined contrast agents in liver MRI are highlighted.
European Journal of Radiology, 2016
In patients with small bowel obstruction (SBO), it is challenging to detect early ischemia. The p... more In patients with small bowel obstruction (SBO), it is challenging to detect early ischemia. The purpose of this study is to evaluate the quantitative and qualitative benefits of virtual monoenergetic image (VMI) reconstruction in the assessment of small bowel mural enhancement on dual source dual energy computed tomography (CT) scans of the abdomen. Materials and methods: Institutional review board approval was obtained, for this retrospective analysis. 72 consecutive patients with acute SBO were scanned using a second generation 128-slice dual source, CT system. Images were reconstructed at VMI energy levels from 40 to 110 keV in 10 keV increments and were analysed quantitatively and qualitatively. Contrast to noise ratios (CNR) and signal to noise ratios (SNR) for mural enhancement were recorded for all VMI datasets and compared to conventional polychromatic images (PCI) at 120 kVp. Subjective analysis of mural enhancement on VMI and PCI was performed by 3 blinded readers. Results: Optimal CNR values for small intestinal mural enhancement were observed at 70 keV. Qualitative assessment revealed that there was no statistical difference in diagnostic accuracy between VMI and PCI. All readers reported improved confidence when assessing the contrast enhancement on the 70 keV VMI dataset and in our series, 2 additional cases of ischemia were identified on this reconstruction. Conclusion: Contrast-enhanced dual source dual energy CT with VMI reconstruction at 70 keV maximizes the CNR of small bowel mural enhancement and increases the overall diagnostic confidence in assessing mural enhancement in patients with SBO.
Lecture Notes in Computer Science, 2015
We present a 2D to 3D registration framework that compensates for prostate motion and deformation... more We present a 2D to 3D registration framework that compensates for prostate motion and deformations during freehand prostate biopsies. It has two major components: 1) a trajectory-based rigid registration to account for gross motions of the prostate; and 2) a non-rigid registration constrained by a finite element model (FEM) to adjust for residual motion and deformations. For the rigid alignment, we constrain the ultrasound probe tip in the live 2D imaging plane to the tracked trajectory from the pre-procedure 3D ultrasound volume. This ensures the rectal wall approximately coincides between the images. We then apply a FEM-based technique to deform the volume based on image intensities. We validate the proposed framework on 10 prostate biopsy patients, demonstrating a mean target registration error (TRE) of 4.63 mm and 3.15 mm for rigid and FEM-based components, respectively.
Urology, 2015
To determine whether multiparametric magnetic resonance imaging (MRI) of the prostate (mpMRI) com... more To determine whether multiparametric magnetic resonance imaging (MRI) of the prostate (mpMRI) combined with MRI fusion technology during transrectal ultrasound-guided biopsy can enhance the detection of significant disease in patients with apparent low-risk prostate cancer on active surveillance (AS). We reviewed the charts of 603 patients on AS for localized prostate cancer between January 2006 and September 2013. mpMRI before repeat transrectal ultrasound-guided biopsy was obtained in 111 patients, of whom 69 underwent subsequent fusion biopsy (39 true and 30 cognitive) in addition to standard template biopsy. The results of fusion biopsy were compared with the standard biopsy. The primary endpoint was termination of AS. mpMRI detected 118 suspicious lesions in 70 patients (63%). Of these, 42 patients (60%) had lesions with Prostate imaging, reporting, and data system (PIRADS) score 3, and 28 patients (40%) had PIRADS score 4 or 5 lesions. AS was terminated in 27 (24.3%) of the 11...
The Journal of Urology, 2014
Multi-parametric MRI of the prostate (mpMRI-P) offers a method to detect the lesions which may be... more Multi-parametric MRI of the prostate (mpMRI-P) offers a method to detect the lesions which may be located outside the usual template of a transrectal ultrasound guided biopsy (TRUSBx), and fusion biopsy enables sampling of them. Here we investigated the utility of mpMRI-P in patients on active surveillance (AS) for the management of lower risk prostate cancer (CaP). Materials & Methods: We reviewed the charts of 603 patients on AS for localized CaP at the Vancouver Prostate Centre. Of these patients 110 had a mpMRI-P prior to repeat TRUSBx, and selected patients underwent MRI-TRUS fusion biopsy based on the mpMRI-P findings, in addition to a standard biopsy. The results of fusion biopsy cores were compared to the standard biopsy cores. Results: mpMRI-P detected 112 suspicious lesion in 72 (65%) patients. Of these, 80 (72%) were PIRADS 3 lesions and 32(28%) PIRADS 4 or 5. Fusion biopsy was carried out in 65 of these patients (37 true and 28 cognitive). Gleason grade progression compared to previous biopsy was detected in 11 (10%) patients in the fusion cores, in 7 (6.3%) patients in the standard cores, and in 3 (2.7%) patients in both fusion and standard cores. Two patients discontinued AS due to size increase of a lesion on mpMRI-P. mpMRI-P with fusion biopsy was responsible for the determination of disease progression in 13(11.8%) cases. Conclusions: These preliminary findings suggest that mpMRI-P with subsequent fusion biopsy enhances the identification of AS patients requiring definitive treatment.
The Journal of Urology, 2014
The most Gleason score findings were 3+3. 48,2% among the patient with one negative biopsy and 70... more The most Gleason score findings were 3+3. 48,2% among the patient with one negative biopsy and 70,5% among the patient with two or more biopsies. RTE detected Gleason 3 + 3 in 79,5 %, Gleason 3 + 4 in 89,8%, Gleason 4 + 3 in 92,3%, Gleason 4+4 in 88%. All cancers with a Gleason score 5 (4+5, 5+4, 5+5) RTE could detect in 100%. CONCLUSIONS: RTE allows an improved detection of PCa in men with previous negative biopsies and was superior to a B/TRUS and to a 12-core systematic randomized biopsy. RTE showes a high detection rate for higher Gleason score. In our view RTE guided biopsy should be primarily considered in re-biopsy setting before recommending more burdensome saturation biopsy.
Canadian Association of Radiologists Journal, 2013
The purpose of this pictorial review is to illustrate the various imaging findings of extrapulmon... more The purpose of this pictorial review is to illustrate the various imaging findings of extrapulmonary tuberculosis. Manifestations of cardiac, central nervous system, head and neck, musculoskeletal, abdominal, genitourinary, and breast tuberculosis will be discussed. Extrapulmonary tuberculosis presents a difficult diagnostic challenge for the radiologist and requires a high index of suspicion, particularly in high-risk populations.
Journal of Emergency Medicine
We would like to thank our printing house Counter Clockwise Design and Production Group for their... more We would like to thank our printing house Counter Clockwise Design and Production Group for their generous support. The UBC Medical Journal uses an open access publishing policy in line with our mandate to publish in a socially responsible way. We endorse open access publishing as the preferred model for scholarly communication and encourage the adoption of open access principles by universities and research agencies. To subscribe, advertise or submit, see our website.
Annals of Hepatology, 2009
Hepatic artery thrombosis (HAT) is relatively infrequent, but possibly a devastating complication... more Hepatic artery thrombosis (HAT) is relatively infrequent, but possibly a devastating complication of orthotopic liver transplantation (OLT). It often requires urgent retransplantation. Two main forms of HAT are recognized as early and late HAT (diagnosis within or after 30 days following LT). Early HAT typically results in graft failure. Late HAT features biliary obstruction, cholangitis, and hepatic abscess formation. We report here the case of a patient of Wilsons disease who presented twelve years post-liver transplant symptoms typical of acute HAT and hepatic infarction. On diagnostic imaging, celiac axis and hepatic artery were thrombosed, resulting in ischemic necrosis of the left hepatic lobe. The resulting sepsis and transient hepatic insufficiency were managed conservatively, and repeat OLT was avoided. The patient remains stable more than one year later. To the best of our knowledge this case report is unique in the literature for the unusually long interval between OLT and late acute HAT, as well as celiac and portal vein occlusion. The acute presentation of sub massive hepatic necrosis is also uncharacteristic of late HAT and more typical of acute HAT. This report describes our experience in managing this and a literature review of the topic.
Radiologic clinics of North America, 2017
Given the high prevalence, increasing incidence, and significant morbidity and mortality related ... more Given the high prevalence, increasing incidence, and significant morbidity and mortality related to hepatocellular carcinoma (HCC), a robust and cost-effective screening and surveillance program is needed. Most societies recommend ultrasound for HCC screening, despite lack of standardization in imaging acquisition, reporting content and language, and follow-up recommendations. The American College of Radiology Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) fills this unmet need by providing standardization in the use of US in at-risk patients. It is anticipated that US LI-RADS will improve the performance of ultrasound for HCC screening and surveillance and unify management recommendations.
International Journal of Surgery Case Reports, 2022
Introduction and importance Although foreign bodies are a rare cause of gastrointestinal tract pe... more Introduction and importance Although foreign bodies are a rare cause of gastrointestinal tract perforation, they may serve as a nidus for hepatic abscess. Abdominal pain is the most common presenting symptom. We present a case of an ingested pen causing duodenal perforation and hepatic abscess several months after initially presenting with a pericardial effusion. Case presentation A 59-year-old female living in an intensive tertiary mental health facility was noted to have an incidental pericardial effusion during work-up for hyponatremia. Seven months later, she developed a new fever and was noted to have interval increase in the pericardial effusion size. This prompted further investigation which finally revealed that an ingested pen had perforated through the first part of the duodenum and caused an abscess in the left lobe of the liver. The pericardial effusion was presumed secondary to local inflammation. Upon discovery of the abscess, the patient underwent successful operative management including abscess drainage, foreign body extraction, and duodenal repair. Clinical discussion Reports of hepatic abscess from foreign body causing duodenal perforation are rare, with bone fragments and toothpicks the most common foreign bodies implicated. There is one other previously reported case of an ingested pen. Abdominal pain is present in up to 85% of cases, but fever may be the only presenting symptom. Conclusion Foreign body migration causing a hepatic abscess may present non-specifically with unexplained fever or even pericardial effusion. Psychiatric comorbidities may contribute to delays in diagnosis due to difficulties recalling the episode of ingestion.
Journal of the American College of Radiology, 2015
The aim of this study was to retrospectively identify trends in the representation of female auth... more The aim of this study was to retrospectively identify trends in the representation of female authorship in prominent general radiology journals over the past 2 decades. Methods: A comprehensive search was conducted for all articles published in 1993, 2003, and 2013 in Radiology, the American Journal of Roentgenology (AJR), European Radiology, and Investigative Radiology. The genders of the first and last authors were collected. Chisquare tests were used for statistical analysis, and P values < .05 were considered to indicate statistical significance. Results: A total of 3,786 articles were reviewed. Overall, women constituted 20.0% authorship, 24.7% of first authors, and 15.2% of senior authors. The average overall female first and senior authorship grew from 19.7% to 32.1% and from 13.6% to 19.1%, respectively from 1993 to 2013. Female first authorship grew over the past 2 decades in the journals reviewed, with significant growth in AJR and Radiology (P < .0001). Female first authorship in the individual journals grew from 16.4%-29.1% in 1993, to 29.1%-34.8% in 2013. Female senior authorship also demonstrated growth in the past 2 decades, growing from 4.3%-17.5% in 1993 to 15.5%-23.2% in 2013. There was significant growth in senior female authorship in Radiology (from 12.1% to 19.2%, P ¼ .004) and European Radiology (from 4.3% to 15.5%, P ¼ .0433). Female senior authorship remained significantly lower than first authorship over the past 2 decades (P ¼ .002, P < .001, and P < .0001). Conclusions: Although women's growth in first authorship in radiology literature is proportional to their growth in the specialty, they continue to remain a minority, especially in senior authorship, and demonstrate similar participation to other medical specialties.
UBC Medical …, 2010
Disease presented to the Emergency Department with abdominal discomfort localized to the left upp... more Disease presented to the Emergency Department with abdominal discomfort localized to the left upper quadrant (LUQ). The discomfort was described as an aching pain of 8/10 severity, periodically radiating to the back. The pain had been present 23 days before ...
Urologia Internationalis, 2011
Objectives: Overdiagnosis is arguably the greatest challenge in the management of men with prosta... more Objectives: Overdiagnosis is arguably the greatest challenge in the management of men with prostate cancer. Multi-parametric (mp)-MRI prior to prostate biopsy may have a role in ruling-in and ruling-out clinically significant disease. Patients and Methods: 114 consecutive men at risk of prostate cancer with previous biopsy underwent mp-MRI prior to transrectal ultrasound (TRUS)-guided biopsies. Standard systematic biopsies were carried out with targeting to suspicious areas. Results: 59.6% had cancer detected by TRUS-guided biopsy. Mean age was 63.6 years (SD 9.0). If men had not been biopsied because of a negative mp-MRI, 21% (24/114) with no cancer and 5% (6/114) with clinically insignificant cancer could have avoided a biopsy. However, 4% (4/114) would have been advised to defer a biopsy that demonstrated the presence of clinically significant cancer. Conclusion: mp-MRI may have a role in ruling-in and ruling-out clinically significant prostate cancer in men at risk prior to biopsy.
Abdominal Radiology, 2021
Purpose This study evaluates the impact of second-opinion review of multiparametric prostate MRI ... more Purpose This study evaluates the impact of second-opinion review of multiparametric prostate MRI for cancer detection by a multidisciplinary review board at a tertiary care center when compared with the initial community radiologist interpretation. Methods Cases were collected retrospectively from multidisciplinary prostate MRI rounds from 2017 to 2020 at a single tertiary care center. Patients with suspected prostate cancer or on active surveillance were referred for consideration of TRUS/ MRI-fusion biopsy based on community-read prostate MRIs. All MRIs were re-read by subspecialized abdominal radiologists and a PI-RADS score assigned. Targeted fusion and 8-12 core systematic biopsy was performed in patients with PIRADS ≥ 3 lesions. Cohen kappa values were used to quantify interobserver agreement. Positive predictive value (PPV) was used to determine accuracy of PI-RADS score for detection of clinically significant prostate cancer (csPCa) (ISUP Grade Group ≥ 2). Results Three hundred and thirty-two lesions in 303 patients were reviewed and 252 lesions in 198 patients biopsied. The PI-RADS score was concordant in 60.5% of lesions, downgraded in 17.8%, and upgraded in 7.8%. Agreement between community and tertiary center interpretation was fair (κ = 0.354), with greater agreement for PI-RADS ≥ 4 (κ = 0.523) than PI-RADS ≥ 3 (κ = 0.456), and peripheral zone (κ = 0.419) than transition zone lesions (κ = 0.251). Prevalence of csPCa in biopsied lesions was 40.9%. Conclusion There is variability in community and tertiary care center interpretation of prostate MRI in cancer detection, with higher concordance rates for higher grade and peripheral zone lesions. These differences demonstrate the added value of multidisciplinary round review and highlight the need for ongoing education and feedback.
Canadian Urological Association journal = Journal de l'Association des urologues du Canada, Jan 6, 2018
The natural history of prostatic lesions identified on multiparametric magnetic resonance imaging... more The natural history of prostatic lesions identified on multiparametric magnetic resonance imaging (mpMRI) is largely unknown. We aimed to describe changes observed over time on serial MRI. All patients with ≥2 MRI studies between 2008 and 2015 at our institution were identified. MRI progression was defined as an increase in Prostate Imaging Reporting and Data System (PI-RADS; version 2) or size of existing lesions, or the appearance of a new lesion PIRADS ≥4. Patients on active surveillance (AS) were analyzed for correlation of MRI progression to biopsy reclassification. A total of 83 patients (54 on AS and 29 for diagnostic purposes) underwent serial MRI, with a mean interval of 1.9 years between scans. At baseline, 115 lesions (66 index, 49 non-index) were identified. Index lesions were more likely than non-index lesions to increase in size ≥2 mm (36.2 vs. 7.3 %; p=0.002). Overall progression was more likely to be seen among the index cohort (34.8 vs. 7.6%; p<0.001). New lesion...
AJR. American journal of roentgenology, Jan 8, 2017
The purpose of this article is to review the general principles, technique, and clinical applicat... more The purpose of this article is to review the general principles, technique, and clinical applications of contrast-enhanced ultrasound of the liver. Proper technique and optimization of contrast-enhanced ultrasound require a balance between maintaining the integrity of the microbubble contrast agent and preserving the ultrasound signal. Established and emerging applications in the liver include diagnosis of focal lesions, aiding ultrasound-guided intervention, monitoring of therapy, and aiding surgical management.
AJR. American journal of roentgenology, Jan 5, 2017
Neurocutaneous syndromes are a heterogeneous group of multisystemic disorders. We review the mult... more Neurocutaneous syndromes are a heterogeneous group of multisystemic disorders. We review the multimodality imaging findings in the disorders with a propensity for intraabdominal disease. We highlight more recently recognized disease patterns and discuss imaging surveillance optimization. Knowledge of varied intraabdominal phenotypic expressions can increase diagnostic rates. Limitation of radiation dose must be considered in screening this tumor-prone population. Early detection of neoplastic findings is critical for morbidity and mortality reduction.
Canadian Association of Radiologists journal = Journal l'Association canadienne des radiologistes, 2017
Magnetic resonance imaging (MRI) has a well-established role as a highly specific and accurate mo... more Magnetic resonance imaging (MRI) has a well-established role as a highly specific and accurate modality for characterizing benign and malignant focal liver lesions. In particular, contrast-enhanced MRI using hepatocyte-specific contrast agents (HSCAs) improves lesion detection and characterization compared to other imaging modalities and MRI techniques. In this pictorial review, the mechanism of action of gadolinium-based MRI contrast agents, with a focus on HSCAs, is described. The clinical indications, protocols, and emerging uses of the 2 commercially available combined contrast agents available in the United States, gadoxetate disodium and gadobenate dimeglumine, are discussed. The MRI features of these agents are compared with examples of focal hepatic masses, many of which have been obtained within the same patient therefore allowing direct lesion comparison. Finally, the pitfalls in the use of combined contrast agents in liver MRI are highlighted.
European Journal of Radiology, 2016
In patients with small bowel obstruction (SBO), it is challenging to detect early ischemia. The p... more In patients with small bowel obstruction (SBO), it is challenging to detect early ischemia. The purpose of this study is to evaluate the quantitative and qualitative benefits of virtual monoenergetic image (VMI) reconstruction in the assessment of small bowel mural enhancement on dual source dual energy computed tomography (CT) scans of the abdomen. Materials and methods: Institutional review board approval was obtained, for this retrospective analysis. 72 consecutive patients with acute SBO were scanned using a second generation 128-slice dual source, CT system. Images were reconstructed at VMI energy levels from 40 to 110 keV in 10 keV increments and were analysed quantitatively and qualitatively. Contrast to noise ratios (CNR) and signal to noise ratios (SNR) for mural enhancement were recorded for all VMI datasets and compared to conventional polychromatic images (PCI) at 120 kVp. Subjective analysis of mural enhancement on VMI and PCI was performed by 3 blinded readers. Results: Optimal CNR values for small intestinal mural enhancement were observed at 70 keV. Qualitative assessment revealed that there was no statistical difference in diagnostic accuracy between VMI and PCI. All readers reported improved confidence when assessing the contrast enhancement on the 70 keV VMI dataset and in our series, 2 additional cases of ischemia were identified on this reconstruction. Conclusion: Contrast-enhanced dual source dual energy CT with VMI reconstruction at 70 keV maximizes the CNR of small bowel mural enhancement and increases the overall diagnostic confidence in assessing mural enhancement in patients with SBO.
Lecture Notes in Computer Science, 2015
We present a 2D to 3D registration framework that compensates for prostate motion and deformation... more We present a 2D to 3D registration framework that compensates for prostate motion and deformations during freehand prostate biopsies. It has two major components: 1) a trajectory-based rigid registration to account for gross motions of the prostate; and 2) a non-rigid registration constrained by a finite element model (FEM) to adjust for residual motion and deformations. For the rigid alignment, we constrain the ultrasound probe tip in the live 2D imaging plane to the tracked trajectory from the pre-procedure 3D ultrasound volume. This ensures the rectal wall approximately coincides between the images. We then apply a FEM-based technique to deform the volume based on image intensities. We validate the proposed framework on 10 prostate biopsy patients, demonstrating a mean target registration error (TRE) of 4.63 mm and 3.15 mm for rigid and FEM-based components, respectively.
Urology, 2015
To determine whether multiparametric magnetic resonance imaging (MRI) of the prostate (mpMRI) com... more To determine whether multiparametric magnetic resonance imaging (MRI) of the prostate (mpMRI) combined with MRI fusion technology during transrectal ultrasound-guided biopsy can enhance the detection of significant disease in patients with apparent low-risk prostate cancer on active surveillance (AS). We reviewed the charts of 603 patients on AS for localized prostate cancer between January 2006 and September 2013. mpMRI before repeat transrectal ultrasound-guided biopsy was obtained in 111 patients, of whom 69 underwent subsequent fusion biopsy (39 true and 30 cognitive) in addition to standard template biopsy. The results of fusion biopsy were compared with the standard biopsy. The primary endpoint was termination of AS. mpMRI detected 118 suspicious lesions in 70 patients (63%). Of these, 42 patients (60%) had lesions with Prostate imaging, reporting, and data system (PIRADS) score 3, and 28 patients (40%) had PIRADS score 4 or 5 lesions. AS was terminated in 27 (24.3%) of the 11...
The Journal of Urology, 2014
Multi-parametric MRI of the prostate (mpMRI-P) offers a method to detect the lesions which may be... more Multi-parametric MRI of the prostate (mpMRI-P) offers a method to detect the lesions which may be located outside the usual template of a transrectal ultrasound guided biopsy (TRUSBx), and fusion biopsy enables sampling of them. Here we investigated the utility of mpMRI-P in patients on active surveillance (AS) for the management of lower risk prostate cancer (CaP). Materials & Methods: We reviewed the charts of 603 patients on AS for localized CaP at the Vancouver Prostate Centre. Of these patients 110 had a mpMRI-P prior to repeat TRUSBx, and selected patients underwent MRI-TRUS fusion biopsy based on the mpMRI-P findings, in addition to a standard biopsy. The results of fusion biopsy cores were compared to the standard biopsy cores. Results: mpMRI-P detected 112 suspicious lesion in 72 (65%) patients. Of these, 80 (72%) were PIRADS 3 lesions and 32(28%) PIRADS 4 or 5. Fusion biopsy was carried out in 65 of these patients (37 true and 28 cognitive). Gleason grade progression compared to previous biopsy was detected in 11 (10%) patients in the fusion cores, in 7 (6.3%) patients in the standard cores, and in 3 (2.7%) patients in both fusion and standard cores. Two patients discontinued AS due to size increase of a lesion on mpMRI-P. mpMRI-P with fusion biopsy was responsible for the determination of disease progression in 13(11.8%) cases. Conclusions: These preliminary findings suggest that mpMRI-P with subsequent fusion biopsy enhances the identification of AS patients requiring definitive treatment.
The Journal of Urology, 2014
The most Gleason score findings were 3+3. 48,2% among the patient with one negative biopsy and 70... more The most Gleason score findings were 3+3. 48,2% among the patient with one negative biopsy and 70,5% among the patient with two or more biopsies. RTE detected Gleason 3 + 3 in 79,5 %, Gleason 3 + 4 in 89,8%, Gleason 4 + 3 in 92,3%, Gleason 4+4 in 88%. All cancers with a Gleason score 5 (4+5, 5+4, 5+5) RTE could detect in 100%. CONCLUSIONS: RTE allows an improved detection of PCa in men with previous negative biopsies and was superior to a B/TRUS and to a 12-core systematic randomized biopsy. RTE showes a high detection rate for higher Gleason score. In our view RTE guided biopsy should be primarily considered in re-biopsy setting before recommending more burdensome saturation biopsy.
Canadian Association of Radiologists Journal, 2013
The purpose of this pictorial review is to illustrate the various imaging findings of extrapulmon... more The purpose of this pictorial review is to illustrate the various imaging findings of extrapulmonary tuberculosis. Manifestations of cardiac, central nervous system, head and neck, musculoskeletal, abdominal, genitourinary, and breast tuberculosis will be discussed. Extrapulmonary tuberculosis presents a difficult diagnostic challenge for the radiologist and requires a high index of suspicion, particularly in high-risk populations.
Journal of Emergency Medicine