Papers by Eric Williamson
Mayo Clinic Proceedings, Apr 1, 2012
Iodinated contrast agents have been in use since the 1950s to facilitate radiographic imaging mod... more Iodinated contrast agents have been in use since the 1950s to facilitate radiographic imaging modalities. Physicians in almost all specialties will either administer these agents or care for patients who have received these drugs. Different iodinated contrast agents vary greatly in their properties, uses, and toxic effects. Therefore, clinicians should be at least superficially familiar with the clinical pharmacology, administration, risks, and adverse effects associated with iodinated contrast agents. This primer offers the non-radiologist physician the opportunity to gain insight into the use of this class of drugs.
Journal of General Internal Medicine, Feb 18, 2009
Fever of unknown origin (FUO) presents a diagnostic challenge. Giant cell arteritis (GCA) may pre... more Fever of unknown origin (FUO) presents a diagnostic challenge. Giant cell arteritis (GCA) may present with FUO and this entity should be included in the differential of elderly patients who present with constitutional symptoms. While a temporal artery biopsy is considered the gold standard for the diagnosis of GCA, a subset of patients with large vessel involvement by GCA may have a negative temporal artery biopsy and no cranial symptoms. We present a 79 year-old woman with FUO and negative temporal artery biopsies in whom diagnosis of GCA was delayed. Further imaging with CT-angiogram and positron emission tomography/computed tomography (PET/CT) scan showed diffuse extensive active vasculitis. The above case underscores the value of imaging studies in the evaluation of patients with FUO from occult large vessel vasculitis.
Journal of Cardiovascular Computed Tomography, Nov 1, 2022
European heart journal. Acute cardiovascular care, Jan 31, 2017
Background: There is limited understanding of the role of cardiac computed tomography angiography... more Background: There is limited understanding of the role of cardiac computed tomography angiography (CCTA) for assessment of patients with spontaneous coronary artery dissection (SCAD). Methods: In this report we describe the diagnostic utility of CCTA in three young women presenting with signs and symptoms of myocardial ischemia who were eventually diagnosed with SCAD. Results: None of the women had traditional atherosclerotic risk factors. SCAD was not initially identified on CCTA in any of the three women, but was visualized during retrospective analysis in two patients after invasive coronary angiography. In two patients follow-up CCTA imaging was used successfully for subsequent management. Conclusions: In patients presenting with signs or symptoms of acute coronary syndrome, SCAD may be missed or not detectable on CCTA. A negative CCTA should not exclude a diagnosis of SCAD, and invasive coronary angiography should be considered for further evaluation.
International Journal of Radiation Oncology Biology Physics, Oct 1, 2016
leading to treatment delay. The key informant interviews with radiation oncologists, medical phys... more leading to treatment delay. The key informant interviews with radiation oncologists, medical physicists, radiation therapists, and supporting staff were transcribed and content and theme analyses were conducted using ATLAS. The number of staff, equipment, and quality of training was compared to IAEA reference standards. Univariate and multivariate logistic regression was used to determine factors increasing the odds of treatment delay. Results: We found that the hospital had one Cobalt-60 machine which, when functioning, treats 30-90 patients per day, with 3000 new patients per year. Based on the patient load, this department needs at least 1 additional teletherapy device, and 2 brachytherapy devices, with 2 generators to prevent treatment cessation during power outages. The number of radiation oncologists should be increased from 8 to 12, medical physicists from 4 to 7, radiation therapists from 6 to 10, and nurses from 6 to 10. Factors found to increase the odds of treatment delay include patient financial status (OR Z 1.4, P < 0.05), healthcare worker strikes (OR Z 1.3, P Z 0.09), power outage (OR Z 1.5, P Z 0.66), machine breakdown (OR Z 3.2, P < 0.05), and distance from hospital (OR Z 2.1, P < 0.05). Conclusion: Barriers to care, treatment capacity, and needs at a radiotherapy center in an under-resourced country have not been well characterized. This study identifies the staff and equipment needs at a radiotherapy department in Nigeria, as well as the factors impairing treatment access. These results can be used to inform efforts to expand the availability of radiotherapy and improve current treatment capacity in Nigeria and in other LMICs.
International Journal of Radiation Oncology Biology Physics, Nov 1, 2018
MC DIBH optimized). These MC optimized plans were then recalculated applying the vRBE model. Comp... more MC DIBH optimized). These MC optimized plans were then recalculated applying the vRBE model. Comparative photon plans (1 3D conformal, 4 "butterfly" IMRT) were generated on the DIBH scan. IMRT was used for patients with mediastinal involvement that extended below the pulmonary artery. Results: All 5 patients were female. Median RWD was 30 Gy (range, 20-30.6). The median CTV/ITV volume receiving 99% RWD or higher (V99) dropped from 99.5% to 48.6% when PBA plans were recalculated using MC. In contrast, the mean of mean RWD to the heart, breast, and lungs were similar across PBA, MC, and MC with vRBE TPA (Table). Mean of mean RWD to the lungs, heart, left main coronary, left circumflex, and left ventricle appeared lower with PT compared with photon DIBH. Mean of mean dose (Gy). Conclusion: MC should be used for PT treatment planning to ensure adequate coverage of mediastinal target volumes. Mean dose estimates to the heart, lungs, and breast were similar across PBA, MC, and MC with vRBE and were similar, if not lower, with PT compared with photons. Long term follow-up is needed to correlate with toxicity.
Radiology, Oct 1, 2022
Practice guidelines CAD-RADS™ 2.0-2022 Coronary Artery Disease-Reporting and Data System an exper... more Practice guidelines CAD-RADS™ 2.0-2022 Coronary Artery Disease-Reporting and Data System an expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR) and the North America society of cardiovascular imaging (NASCI)
Mayo Clinic Proceedings, Sep 1, 2011
T he standard of care to correct severe mitral regurgitation (MR) due to degenerative mitral valv... more T he standard of care to correct severe mitral regurgitation (MR) due to degenerative mitral valve (MV) disease is MV repair. In studies comparing MV repair with MV replacement with a prosthetic valve, repair achieved better survival and equivalent, if not better, durability. The availability of a reproducible MV repair technique as a safe and reliable alternative to prosthetic replacement has influenced the indications for surgical intervention in patients with MR due to leaflet prolapse. After successful MV repair, patients who maintain sinus rhythm resume full activities and do not need long-term anticoagulant therapy. Compliance with international guidelines 1 recommending early MV repair has been heterogeneous for 3 main reasons: (1) hesitancy of some otherwise active and asymptomatic individuals to accept the need for an invasive cardiac surgical procedure; (2) reluctance of cardiologists to refer such patients for an
The Journal of thoracic and cardiovascular surgery, Jan 7, 2018
Calcification of the ascending aorta complicates aortic valve replacement. Transcatheter aortic v... more Calcification of the ascending aorta complicates aortic valve replacement. Transcatheter aortic valve replacement is an alternative procedure in this situation, but it requires manipulation through the hostile area in the ascending aorta. We reviewed our transcatheter aortic valve insertion experience to better understand the surgical mortality risk of valve insertion in patients with extensive calcification of the ascending aorta. We retrospectively reviewed the records of 665 consecutive patients who received transcatheter aortic valve insertion from November 2008 through December 2015. We defined a hostile ascending aorta on the basis of preoperative computed tomography scan documenting significant aortic calcification that the surgeon believed precluded safe aortic cross-clamp application. There were 36 patients (5%) who met our definition of a hostile ascending aorta (hostile aorta group) and 629 (95%) who did not (control group). Surgical mortality occurred in 2 patients (6%) ...
The Journal of Thoracic and Cardiovascular Surgery, 2017
Objective: There are limited data on transcatheter aortic valve insertion after previous mitral v... more Objective: There are limited data on transcatheter aortic valve insertion after previous mitral valve operation. To better understand the associated procedural risks, we reviewed our single-center experience. Methods: We retrospectively reviewed the records of 772 consecutive patients who received transcatheter aortic valve insertion from November 2008 through August 2016. There were 18 (2%) patients who had previous mitral valve operation that included valve repair in 4 patients (22%) and replacement in 14 (78%). Results: Baseline characteristics included age of 77 years (interquartile range 68, 84), female sex in 11 patients (61%), New York Heart Association functional class III/IV in 14 (78%), and Society of Thoracic Surgeons predicted risk of mortality of 7.0% (5.3, 12.0). Access was transfemoral in 14 patients (78%). Valve insertion was successful in all patients and involved a balloon expandable device in 10 (56%). No patient experienced acute mitral valve dysfunction or procedure-related mortality. Follow-up echocardiography demonstrated mean systolic aortic valve gradient of 9 mm Hg (8, 12), no grade moderate or greater aortic paravalvular regurgitation, and stable mitral valve function. Kaplan-Meier estimated survival was 90.9% AE 9.1% at 1 year. Conclusions: Transcatheter aortic valve insertion appears to be a safe and effective operation after previous mitral valve operation. Procedure success was achieved with both balloon expandable and self-expanding devices and was independent of arterial access method. Transcatheter valve insertion should not be denied strictly on the basis of a previous mitral valve operation.
JACC. Cardiovascular interventions, Jan 9, 2017
The Journal of Thoracic and Cardiovascular Surgery, 2017
Objective: Native aortic valve calcium and transcatheter aortic valve oversize have been reported... more Objective: Native aortic valve calcium and transcatheter aortic valve oversize have been reported to predict pacemaker implantation after transcatheter aortic valve insertion. We reviewed our experience to better understand the association. Methods: We retrospectively reviewed the records of 300 patients with no prior permanent pacemaker implantation who underwent transcatheter aortic valve insertion from November 2008 to February 2015. Valve oversize was calculated using area. The end point of the study was 30-day postoperative pacemaker implantation. Results: Patient data included age of 81.1 AE 8.4 years, female sex in 135 patients (45%), atrial fibrillation in 74 patients (24.7%), Society of Thoracic Surgeons predicted risk of mortality of 7.6% (interquartile range [IQR], 5.3-10.6), aortic valve calcium score of 2568 (IQR, 1775-3526) Agatston units, and annulus area of 471 AE 82 mm 2. Balloon-expandable valves were inserted in 244 patients (81.3%). Transcatheter aortic valve oversize was 12.8% (IQR, 3.9-23.3). Pacemaker implantation was performed in 59 patients (19.7%). Aortic valve calcium score (adjusted P ¼ .275) and transcatheter valve oversize (adjusted P ¼ .833) were not independent risk factors for pacemaker implantation when controlling for preoperative right bundle branch block (adjusted odds ratio, 3.49; 95% confidence interval, 1.61-8.55; P ¼ .002), implantation of self-expanding valve (adjusted odds ratio, 4.09; 95% confidence interval, 1.53-10.96; P ¼ .005), left bundle branch block (adjusted P ¼ .331), previous percutaneous coronary intervention (adjusted P ¼ .053), or valve surgery (adjusted P ¼ .111), and PR interval (adjusted P ¼ .350). Conclusions: Right bundle branch block and implantation of a self-expanding prosthesis were predictive of pacemaker implantation, but not native aortic valve score or transcatheter valve oversize.
European Heart Journal, 2013
Cath lab disasters-the interventionalists' nightmares! 1127 segment of left vertebral artery. The... more Cath lab disasters-the interventionalists' nightmares! 1127 segment of left vertebral artery. The patient underwent PTA and stent placement of the left subclavian artery. During one-year follow-up period, he was symptom free, ultrasound showed normal flow in left subclavian artery, and regional wall motion of LV appeared to be normal. Discussion: Clinical manifestation of a coronary-subclavian steal in this patient was unusual with the severe angina but without any symptoms of cerebral ischemia probably due to partly functioning carotid-subclavian graft. Percutaneous revascularization of the subclavian artery was the reasonable treatment option. That lesion was more significant than stenosis of carotid-subclavian graft, more favorable for PTA due to minimal calcification and relatively short stenosis. Conclusions: Coronary-subclavian steal syndrome is a diagnosis that should not be overlooked, especially in patients with known peripheral atherosclerosis. Percutaneous interventions due to their efficacy and low complication rates constitute the first choice treatment in patients with high surgical risk.
JACC: Cardiovascular Imaging, 2016
PURPOSE Lower kV has a great potential to reduce radiation dose in CT; however, its practical imp... more PURPOSE Lower kV has a great potential to reduce radiation dose in CT; however, its practical implementation has been hampered by lack of quantitative tools to guide the selection of proper kV and mAs for each patient. Our goal is to assess a novel automatic kV selection tool in reducing radiation dose while maintaining diagnostic quality in CT angiography (CTA). METHOD AND MATERIALS 101 CTA exams (162 scans) were performed using an automatic kV selection tool (CAREkV, Siemens) on a 128 slice scanner (Definition AS+; Siemens). The CAREkV software used the CT topogram to predict the optimal kV and mAs, taking into account automatic exposure control, tube current limit, and diagnostic task. Two vascular radiologists subsequently evaluated the image sharpness, noise, noise texture, artifacts and diagnostic confidence of these exams using a modified scale from European Guidelines on Quality Criteria. In a subset of lower-kV patients who had prior studies (28 patients, 44 scans), side-by...
Circulation. Arrhythmia and electrophysiology, 2014
Mayo Clinic Proceedings, 2012
Iodinated contrast agents have been in use since the 1950s to facilitate radiographic imaging mod... more Iodinated contrast agents have been in use since the 1950s to facilitate radiographic imaging modalities. Physicians in almost all specialties will either administer these agents or care for patients who have received these drugs. Different iodinated contrast agents vary greatly in their properties, uses, and toxic effects. Therefore, clinicians should be at least superficially familiar with the clinical pharmacology, administration, risks, and adverse effects associated with iodinated contrast agents. This primer offers the non-radiologist physician the opportunity to gain insight into the use of this class of drugs.
Journal of the American College of Cardiology, 2011
Journal of the American College of Cardiology, 2014
Background: Computed tomography-myocardial perfusion imaging (CT-MPI) with or without coronary CT... more Background: Computed tomography-myocardial perfusion imaging (CT-MPI) with or without coronary CT angiography (cCTA) is a novel non-invasive method for the assessment of coronary artery disease (CAD) but it is not well established how its diagnostic performance compares to conventional coronary angiography (CA) and fractional flow reserve (FFR).
Journal of General Internal Medicine, 2009
Fever of unknown origin (FUO) presents a diagnostic challenge. Giant cell arteritis (GCA) may pre... more Fever of unknown origin (FUO) presents a diagnostic challenge. Giant cell arteritis (GCA) may present with FUO and this entity should be included in the differential of elderly patients who present with constitutional symptoms. While a temporal artery biopsy is considered the gold standard for the diagnosis of GCA, a subset of patients with large vessel involvement by GCA may have a negative temporal artery biopsy and no cranial symptoms. We present a 79 year-old woman with FUO and negative temporal artery biopsies in whom diagnosis of GCA was delayed. Further imaging with CT-angiogram and positron emission tomography/computed tomography (PET/CT) scan showed diffuse extensive active vasculitis. The above case underscores the value of imaging studies in the evaluation of patients with FUO from occult large vessel vasculitis.
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Papers by Eric Williamson