A Comparison of CT-Guided Bone Biopsy and Fluoroscopic-Guided Disc Aspiration as Diagnostic Methods in the Management of Spondylodiscitis.

BACKGROUND AND PURPOSE: Percutaneous tissue biopsy is a key step in the diagnosis and management of spondylodiscitis, often utilizing CT-guided bone biopsy or fluoroscopic-guided disc aspirations. Our objective was to compare radiation exposure, procedure time, sedation requirement & yield between the two modalities. MATERIALS AND METHODS: 103 patients in 2 cohorts underwent fluoroscopic-guided disc aspirations (n = 47) or CTguided bone biopsy (n = 46) for diagnosis of spondylodiscitis. Patient and imaging data were gathered to ensure matched cohorts. Interventional and post-procedural data included radiation exposure, procedure time, complications, and microbiological details. Yield was calculated using MRI findings as the gold standard for infection. RESULTS: There were no significant differences between cohorts in demographics, symptom duration, or pre-procedure antibiotics use. CT-guided bone biopsy required more general anesthesia (26% vs 0%, P < 0.001), had longer radiation exposure time (60 ± 24s vs 2 ± 3s, P < 0.001), radiation dose (114.4 ± 71.6 mGy vs 70.4 ± 147.2 mGy), and procedure time (62 ± 14m vs 31 ± 23m, P < 0.001) than fluoroscopic-guided disc aspirations. There was no significant difference in yield (34% vs 32%, P = 0.661), and it was not affected by antibiotic use. CONCLUSIONS: Both modalities have similar utility in isolating causative organisms in suspected cases of spondylodiscitis. Our results suggest that increased radiation exposure, longer procedure time, and increased anesthesia use are relative disadvantages of CT-guided biopsy without an increase in yield. Controlled trials may be beneficial in determining the optimal choice in different scenarios.

High-Resolution Magnetic Resonance Vessel Wall Imaging for the Evaluation of Intracranial Vascular Pathology.

Intracranial vessel wall imaging (IVWI) is an advanced MR imaging technique that allows for direct visualization of the walls of intracranial blood vessels and detection of subtle pathologic vessel wall changes before they become apparent on conventional luminal imaging. When performed correctly, IVWI can increase diagnostic confidence, aid in the differentiation of intracranial vasculopathies, and assist in patient risk stratification and prognostication. This review covers the essential technical underpinnings of IVWI and presents emerging clinical research highlighting its utility for the evaluation of multiple intracranial vascular pathologies.

Special report of the RSNA COVID-19 task force: systematic review of outcomes associated with COVID-19 neuroimaging findings in hospitalized patients.

OBJECTIVE: We reviewed the literature to describe outcomes associated with abnormal neuroimaging findings among adult COVID-19 patients. METHODS: We performed a systematic literature review using PubMed and Embase databases. We included all studies reporting abnormal neuroimaging findings among hospitalized patients with confirmed COVID-19 and outcomes. Data elements including patient demographics, neuroimaging findings, acuity of neurological symptoms and/or imaging findings relative to COVID-19 onset (acute, subacute, chronic), and patient outcomes were recorded and summarized. RESULTS: After review of 775 unique articles, a total of 39 studies comprising 884 COVID-19 patients ≥ 18 years of age with abnormal neuroimaging findings and reported outcomes were included in our analysis. Ischemic stroke was the most common neuroimaging finding reported (49.3%, 436/884) among patients with mortality outcomes data. Patients with intracranial hemorrhage (ICH) had the highest all-cause mortality (49.7%, 71/143), followed by patients with imaging features consistent with leukoencephalopathy (38.5%, 5/13), and ischemic stroke (30%, 131/436). There was no mortality reported among COVID-19 patients with acute disseminated encephalomyelitis without necrosis (0%, 0/8) and leptomeningeal enhancement alone (0%, 0/12). Stroke was a common acute or subacute neuroimaging finding, while leukoencephalopathy was a common chronic finding. CONCLUSION: Among hospitalized COVID-19 patients with abnormal neuroimaging findings, those with ICH had the highest all-cause mortality; however, high mortality rates were also seen among COVID-19 patients with ischemic stroke in the acute/subacute period and leukoencephalopathy in the chronic period. ADVANCES IN KNOWLEDGE: Specific abnormal neuroimaging findings may portend differential mortality outcomes, providing a potential prognostic marker for hospitalized COVID-19 patients.

ACR Appropriateness Criteria Facilitate Judicious Use of CT Angiography for Stroke Workup in the Emergency Department.

PURPOSE: CT angiography (CTA) of the head and neck plays a key role in the evaluation of patients with stroke in the emergency department, particularly to evaluate for large-vessel occlusion and consider patients for mechanical thrombectomy. However, CTA is not always indicated and has various costs. The aim of this study was to examine the correlation between ACR imaging appropriateness recommendations and findings explanatory for stroke on CTA of the head and neck. METHODS: CTA head and neck examinations of emergency department patients performed to evaluate for stroke between January 1, 2019, and June 30, 2019, were retrospectively reviewed. Patients with previously known acute infarct, with primary concern for or discovered hemorrhage, or being evaluated for trauma were excluded. Presenting symptoms were classified on the basis of the most recent ACR Appropriateness Criteria, into three categories: "usually appropriate" (UA), "may be appropriate" (MBA), or "usually not appropriate" (UNA). The percentage of examinations with findings explanatory for stroke were compared among the three groups using the Fisher exact test. RESULTS: A total of 707 cases were reviewed, of which 317 were included; 199 fell into the UA category, 38 MBA, and 80 UNA. For UA, 57 of 199 CTAs (29%) had findings explanatory for stroke, compared with 1 of 38 (3%) in the MBA group (difference, 26%; 95% confidence interval, 13%-34%; P < .001) and 1 of 80 (1%) in the UNA group (difference, 27%; 95% confidence interval, 19%-35%; P < .001). CONCLUSIONS: ACR Appropriateness Criteria recommendations correlate with imaging findings explanatory for stroke and may guide the judicious use of CTA for suspected stroke workup.

The Role of Minimally Invasive Spinal Surgical Procedures in the Elderly Patient: An Analysis of 49 Patients Between 75 and 95 Years of Age.

As the population gets older, yet remains active, the number of patients presenting with symptomatic spinal disease over the age of 75 increases. These include pain from osteoporotic spinal fractures, lumbar degenerative disease, as well as radiculopathy or neurogenic claudication from stenosis over the age of 75 and older increases. While some of these patients are very healthy, taking minimal medication, many are not good candidates for more invasive surgical procedures under general anesthesia because of medical co-morbidities such as insulin-dependent diabetes and medication use such as anti-coagulants. Past reviews of lumbar surgery in elderly patients have examined the risk factors with spinal fusion and multilevel surgery and many were written before the recent advent of more minimally invasive spinal procedures that reduce both operative time and the need for general anesthesia. This review examines effectiveness in return to activity and reduction in pain in these elderly patients stratified by underlying disease category, i.e. fractures, stenosis with neurogenic claudication and chronic pain, rather than just by the procedure, since there are often several minimally invasive procedures that are available. This review demonstrates very similar pain relief outcomes as measured by the visual analog scale (VAS) scores which dropped in the range of 70% or more with the different procedures. Since the majority of these procedures involve short surgical times and minimal blood loss with small incisions that lower the risk of wound infection as well as cardio-respiratory stress and can be performed under local anesthesia as an outpatient, they are particularly advantageous for the properly selected elderly patient.

The Use of Vertiflex® Interspinous Spacer Device in Patients With Lumbar Spinal Stenosis and Concurrent Medical Comorbidities.

The use of the Vertiflex® interspinous spacer is a recent minimal invasive procedure useful in the treatment of lumbar spinal stenosis (LSS). It is used mostly by interventional pain physicians who can also perform the minimally invasive lumbar decompression (MILD procedure). Previously when a patient had clinical symptomatic neurogenic claudication (NC) and radiologic findings of lumbar stenosis and had failed conservative treatment, the options were decompressive laminectomy, laminectomy with pedicle fixation at one or more levels or laminotomy combined with interlaminar stabilization (Coflex® implant). These procedures were performed by neurosurgeons and orthopedic spine surgeons. However, the majority of patients with LSS are elderly and have multiple comorbidities that can make open spinal surgery, even when limited to one level, an anesthesia risk as well as vulnerable to the risk associated with hospitalization and recovery after spine surgery. The minimally invasive approaches to interspinous stabilization make it possible to treat localized symptomatic stenosis in a broader group of patients that do not want or cannot, have general anesthesia or extensive lumbar surgery, especially in the prone position. This article examines the use of the Vertiflex® implant in an elderly population with significant comorbidities that underwent successful outpatient implantation at one or two levels. In addition, it serves to familiarize spine surgeons about the possibility of using more minimal approaches to treat LSS.

Cauda Equina Syndrome in a Patient with Intradural Schwannoma at the Same Level as an Acute L2 Compression Fracture.

Intradural tumors are found often as either incidental findings or during evaluation during magnetic resonance imaging (MRI) for lumbar and/or radicular pain. This patient presented with an acute L2 compression fracture, however, the initial MRI identified a large spinal mass separate from the fracture but at the same level. The patient had acute upper lumbar pain after a fall but the neurologic examination also revealed findings of early cauda equina syndrome with muscle weakness, asymmetric leg numbness, and urinary incontinence. Further history revealed the patient had been using a cane for several months and having difficulty walking with some upper lumbar pain but had not seen a physician. The differential was an extruded disc associated with the fractured endplate versus a tumor. Because of the neurologic symptoms, emergency open decompression combined with multilevel screw fixation was performed. At the time of the laminectomy, the dura bulged posteriorly, no ventral disc was found, and a 3-cm intradural schwannoma was successfully excised with rapid neurologic recovery. The article will review the relationship of cauda equina syndrome with osteoporotic fractures and the rarity of actual true disc extrusion with compression fractures, as well as the more common relationship of finding cauda equina syndrome with intradural tumors when there is severe canal stenosis as seen in this unusual case.

Treatment of a High-risk Thoracolumbar Compression Fracture Using Bilateral Expandable Titanium SpineJack Implants.

In this case, an 80-year-old active patient developed an acute osteoporotic fracture after a fall at L1 above a previous interlaminar implant at L4-5 for stenosis with neurogenic claudication. Radiologic studies found both intra-discal and intra-vertebral vacuum clefts that are highly correlated with instability and progressive kyphosis. Long-term experience with kyphoplasty has shown that acute and subacute fractures can often be re-expanded; however, over three months to one year, the correction is frequently lost and the vertebral height continues to decrease leading to increased risk of both continued deformity and especially adjacent level fractures. The use of newly available titanium intra-vertebral implants combined with bone cement restores and maintains vertebral height and correction of deformities. Long-term studies also demonstrate a reduced risk of adjacent level fractures compared to balloon kyphoplasty. Using vertebral body implants that remain in place within the fractured vertebral body the initial height correction can be better maintained leading to less adjacent level fractures.

An Unusual Vertical T12 Fracture Extending into the T12-L1 Disc in a Patient with Diffuse Idiopathic Spondylotic Hyperostosis: A Case Study Using Vertebroplasty to Stabilize the Fracture.

Osteoporotic spinal fractures are seen above previous spinal instrumentation and also found in patients with diffuse idiopathic spondylotic hyperostosis (DISH). In both situations, there is marked spinal rigidity with a limited mobile spinal section that is vulnerable to motion and subsequent fracture with no or minimal trauma especially when there is concurrent osteoporosis. This is an unusual case where the patient developed a vertical anterior avulsion type fracture of T12 through a large bridging spondylotic ventral spur of bone, resulting in severe positional pain above a previous lumbar instrumented fusion. While being managed conservatively with bracing, sequential follow-up magnetic resonance imaging (MRI) and computed tomography (CT) scans showed progressive development of vacuum changes, both in the linear fracture and the adjacent intra-discal space. Vacuum changes are a strong radiologic sign of spinal instability. Because of age and not wanting to undergo further extensive fusion, he was treated with intra-discal and transpedicular placement of bone cement with the resolution of his pain.

Radiologic Evaluation Of Lumbar Spinal Stenosis: The Integration Of Sagittal And Axial Views In Decision Making For Minimally Invasive Surgical Procedures.

Radiologic findings in combination with clinical symptoms are critical in the diagnosis and evaluation of the severity of lumbar spinal stenosis (LSS) as well as the need for surgical treatment. Dynamic radiographs, computerized tomography (CT), and magnetic resonance imaging (MRI) each provide different but interrelated pieces of information in the patient with lumbar spinal stenosis. Making a treatment decision based only on one of the radiographic studies may negatively affect the treatment outcome. Minimal procedures are predicated on identifying and performing surgery on a limited segment of the lumbar spinal canal affected by the stenosis compared to what occurs during open surgery where the judgment of the spine surgeon often expanded the decompression area based on real-time intra-operative findings correlated with radiologic findings of stenosis. As newer, less invasive procedures are gaining acceptance for surgical treatment of spinal stenosis with symptomatic claudication, radiologic studies become more critical in selecting the correct procedure since there may be no or minimal surgical visual confirmation of the pathology. This article will review how the finding of spinal deformity and motion, canal dimensions, viewed in multiple planes and the presence of facet fluid impact treatment decisions. Differences in these abnormal radiologic findings can affect the selection of surgical procedures ranging from open decompression with pedicle fixation, decompression with interlaminar stabilization, minimally invasive lumbar decompression, and percutaneous interspinous implants providing distraction without decompression. With the development of less invasive procedures, lumbar spinal stenosis is being evaluated and treated not only by spine surgeons but also by interventional pain and neuroradiology physicians that may not be totally familiar with the complexity of the pathology and neuro-radiology of LSS. Each radiologic study provides different information. The goal of this report is to provide a framework for the use of studies such as plain X-rays, dynamic films, MRI, and CT scans as well as the importance of different views, and how to use them in evaluating the abnormal radiologic anatomy seen with LSS and in selecting the most appropriate procedure.

Intracranial aneurysms at higher clinical risk for rupture demonstrate increased wall enhancement and thinning on multicontrast 3D vessel wall MRI.

OBJECTIVE:: Identification of aneurysms at risk for rupture is important and challenging. We sought to evaluate if intracranial vessel wall (IVW) imaging characteristics of unruptured aneurysms correlate with clinical risk factors for rupture. METHODS:: Patients with unruptured intracranial aneurysms were prospectively recruited and underwent a multi contrast 3D IVW protocol between April 6, 2016 and August 29, 2017. Two independent raters, blinded to aneurysm vulnerability, evaluated each aneurysm for wall enhancement, extent of enhancement in terms of the numbers of quadrants enhancing circumferentially, intensity of enhancement, and qualitative wall thinning. PHASES score was calculated for each aneurysm. Univariate logistic regression analysis was used to compare IVW characteristics between aneurysms at higher clinical risk for rupture (PHASES score > 3) and lower clinical risk for rupture (PHASES score ≤ 3). RESULTS:: 45 patients with 65 unruptured aneurysms were analyzed; 38 aneurysms with PHASES score > 3 (58%) and 27 aneurysms with PHASES score ≤ 3 (42%). Aneurysms with PHASES score > 3 were more likely to demonstrate enhancement (42.1% vs 14.8%, p = 0.022), greater extent of enhancement (mean: 2.9 vs 2.2 quadrants, p = 0.063), and wall thinning (9.2% vs 0%, p = 0.044). Inter-reader agreement was moderate-to-good for the presence (κ = 0.64), extent (κ = 0.64), and intensity of enhancement (κ = 0.60) but relatively low for wall thinning (κ = 0.25). CONCLUSION:: Aneurysms at higher risk of rupture by PHASES score are more likely to demonstrate wall enhancement, more diffuse enhancement, and wall thinning on IVW. ADVANCES IN KNOWLEDGE:: This study prospectively compares IVW-detected wall enhancement and thinning between unruptured aneurysms stratified into high and low risk groups by clinical scores (PHASES) of vulnerability.

Two Cases with Incidental Finding of Large Asymptomatic Intradural Lumbar Tumors.

Benign lumbar intradural tumors are statistically uncommon and usually present with complaints of back pain with or without radicular neurological complaints. This report involves two separate patients that were found incidentally to have large intradural tumors without any neurologic complaints. In both cases the tumors were discovered when having magnetic resonance imaging (MRI) after minor auto accidents. Neither patient had any pre-existing lumbar or neurologic complaints. The report will review the different regions and types of incidental findings commonly seen on lumbar MRI scans and the need for close follow-up in patients with incidental lesions such as tumors.

Metastatic Breast Carcinoma to the Coronaries: A Rare Cause of Acute Myocardial Infarction.

A 63-year-old female with a history of invasive ductal breast carcinoma presented to the emergency department with symptoms characteristic of myocardial infarction. Electrocardiography showed sinus tachycardia and ST elevations in leads II, III, and aVF, consistent with inferior wall myocardial infarction. A computed tomography (CT) scan of the chest, abdomen, and pelvis with intravenous contrast demonstrated widespread intrathoracic metastatic disease. Cardiac magnetic resonance imaging (MRI) with contrast revealed obstruction of the left ventricular (LV) outflow tract by an LV mass. Cardiac MRI enabled detection of a rare case of myocardial infarction secondary to tumor emboli and intracavitary LV metastasis. This case report emphasizes the role of cross-sectional imaging including CT and cardiac MRI for unusual causes of myocardial infarction, particularly when associated with neoplastic processes.

Nondisseminated histoplasmosis of the trachea.

Histoplasma capsulatum can rarely affect the trachea. We report the case of a 68-year-old woman with rheumatoid arthritis on immunosuppressive therapy who presented with fevers, worsening shortness of breath, nonproductive cough and subjective throat hoarseness and fullness. Chest computed tomography demonstrated no tracheal findings. Bronchoscopy found mucosal irregularity, nodularity and vesicular regions in the proximal trachea extending seven centimeters distal to the vocal cords. Also seen was an edematous, exudative left vocal cord with polyps and an ulcerative lesion. Silver staining and culture and wash of the tracheal biopsy revealed Histoplasma capsulatum. She was treated with oral itraconazole then briefly on intravenous amphotericin for rising Histoplasma urinary antigen levels. She continued treatment 24 months following diagnosis with minimal dyspnea. Histoplasma tracheitis has been proposed as an indicator of disseminated infection. However, our patient did not demonstrate other organ manifestations. Histoplasma tracheitis should be considered in a differential diagnosis of tracheal lesions even in the absence of systemic involvement.

High-Intensity Focused Ultrasound: Current Status for Image-Guided Therapy.

Image-guided high-intensity focused ultrasound (HIFU) is an innovative therapeutic technology, permitting extracorporeal or endocavitary delivery of targeted thermal ablation while minimizing injury to the surrounding structures. While ultrasound-guided HIFU was the original image-guided system, MR-guided HIFU has many inherent advantages, including superior depiction of anatomic detail and superb real-time thermometry during thermoablation sessions, and it has recently demonstrated promising results in the treatment of both benign and malignant tumors. HIFU has been employed in the management of prostate cancer, hepatocellular carcinoma, uterine leiomyomas, and breast tumors, and has been associated with success in limited studies for palliative pain management in pancreatic cancer and bone tumors. Nonthermal HIFU bioeffects, including immune system modulation and targeted drug/gene therapy, are currently being explored in the preclinical realm, with an emphasis on leveraging these therapeutic effects in the care of the oncology patient. Although still in its early stages, the wide spectrum of therapeutic capabilities of HIFU offers great potential in the field of image-guided oncologic therapy.

Comparative study of endoscopy vs. transjugular intrahepatic portosystemic shunt in the management of gastric variceal bleeding.

BACKGROUND AND AIM: Gastric varices are associated with high mortality. There have been conflicting reports on whether endoscopic treatment with cyanoacrylate or the placement of a transjugular intrahepatic portosystemic shunt (TIPS) is more effective in the treatment of gastric varices. We compared the outcomes of patients treated with cyanoacrylate glue or TIPS for the management of acute gastric variceal bleeding. METHODS: The study was designed as a retrospective cohort analysis of patients undergoing either TIPS or endoscopic treatment with cyanoacrylate for acute gastric variceal bleeding at our institution from 2001 to 2011. Primary compared to studied between the two treatment modalities were the short-term treatment outcomes, including re-bleeding within 30 days, length of hospital stay and in-hospital mortality. Kaplan-Meier survival analysis was performed to assess factors associated with in-hospital mortality. RESULTS: A total of 169 patients were included in the analysis. The TIPS arm contained 140 patients and the cyanoacrylate arm contained 29 patients. There was no evidence to suggest any significant differences in demographics or disease severity. There were no differences between the TIPS arm and the cyanoacrylate armtwo groups in treatment outcomes including re-bleeding within 30 days (17.4% vs. 17.2%; P = 0.98), median length of stay in the hospital (4.5 days vs. 6.0 days; P = 0.35) or in-hospital mortality (9.0% vs. 11.1%; P = 0.74). In-hospital mortality was evaluated for 149 patients and lower albumin (P = 0.015), higher MELD score (P < 0.001), higher CTP score (P = 0.005) and bleeding (P = 0.008) were all significantly associated with in-hospital death. CONCLUSION: These findings suggest that both treatments are equally effective. Cyanoacrylate offers a safe, effective alternative to TIPS for gastric varices, and physician may choose the best therapy for each patient, factoring in the availability of TIPS or cyanoacrylate, the individual patient's presentation, and cost.

Impact of transjugular intrahepatic portosystemic shunt on post-colectomy complications in patients with ulcerative colitis and primary sclerosing cholangitis.

OBJECTIVE: Primary sclerosing cholangitis (PSC) occurs in approximately 5% of patients with ulcerative colitis (UC). The risk of colon cancer is higher in patients undergoing colectomy, who have simultaneous PSC & UC. Our aim was to study the impact, in terms of post-colectomy survival and complications, of transjugular intrahepatic portosystemic shunt (TIPS) before colectomy in these patients. METHODS: In this retrospective, case-control study, information was obtained on demographics, disease characteristics, TIPS characteristics, and post-colectomy complications. Nine patients with PSC and UC who underwent TIPS prior to colectomy (the Study group) and 37 patients with PSC and UC who underwent only colectomy without TIPS (the Control group) were included. Either an analysis of variance or the non-parametric Kruskal-Wallis test were used for continuous variables and Fisher's Exact test or Pearson's chi-squared test was used for categorical factors. RESULTS: There was no difference in the mean age between the two groups; however patients in the Study group had lower platelet count (P = 0.005) as well as higher Model for End- Stage Liver disease (MELD) scores (P < 0.001). Also, patients in the Study group had increased PSC severity as determined by Mayo PSC Risk Scores (1.50 vs. 0.20) (P = 0.001). Total bilirubin levels were higher in the Study group (2.3 vs. 0.8 mg/dL) (P = 0.011). Comparing the post-operative complication rates without adjusting for disease severity, the Study group had more wound infections (P = 0.034), more wound dehiscence (P = 0.022), and a higher re-admission rate within 30 days (P = 0.032); however, the post-operative mortality was not significantly different. CONCLUSION: Patients with PSC and UC who underwent TIPS prior to colectomy had higher rates of complications; however, this was probably due to the greater severity of cirrhosis and PSC in this population.

Management of ureteral obstruction in crossed fused renal ectopia: A case report.

Crossed fused renal ectopia is a rare congenital malformation. We describe a case in which a 58-year-old male with left-sided crossed fused renal ectopia presented with urinary bladder outlet obstruction due to metastatic prostate adenocarcinoma. Glomerular filtration rate (GFR) was 13 mL/min, creatinine 4 mg/dL, and blood urea nitrogen (BUN) 58 mg/dL. The patient underwent successful image-guided placement of percutaneous nephrostomy tubes which were later converted to nephroureteral stents. Labs improved to a GFR of 28 mL/min, creatinine of 2.4 mg/dL, and BUN of 41 mg/dL. In this case standard image-guided renal decompression techniques were effective in treating a patient with crossed fused renal ectopia.

Importance of SPECT/CT images in a case to differentiate a chest wall soft tissue infection from pneumonia on 111In-tagged WBC scintigraphy.

A 52-year-old man presented to the emergency department with a 3-day history of fevers and left flank pain radiating to the chest and neck. Total WBC count was 20,000/uL. Abdominal CT demonstrated small bibasilar pleural effusions. Because of persistent leukocytosis, an In WBC scintigram was ordered 5 days after admission, which demonstrated thoracic WBC accumulation on the planar images that localized to the left posterior chest wall on SPECT/CT. SPECT/CT may differentiate intrathoracic versus extrathoracic disease.

Incidence of hypercoagulable events after image-guided percutaneous cryoablation of renal tumors: a single-center experience.

PURPOSE: To identify retrospectively hypercoagulable events that occurred over time in patients who underwent image-guided percutaneous renal cryoablation and compare the incidence with a cohort of patients who underwent surgical partial nephrectomy (PN) during the same time period. MATERIALS AND METHODS: An electronic medical record database was queried for patients who underwent percutaneous image-guided renal mass cryoablation or PN between September 2006 and June 2012. Records were examined for thrombotic events during the year following the procedure in each group. Incidence rates, Kaplan-Meier estimates, and patient demographic variables were compared using the stratified log-rank test and t test for independent samples. RESULTS: The study comprised 114 cryoablation cases. The cumulative incidence of thrombotic events after 1 year was 4.39%. The incidence per 100 person-years was 4.84. There were 105 PN cases. The cumulative incidence of thrombotic events after 1 year was 1.0%. The incidence per 100 person-years was 1.14. The person-time incidence rate difference for these two groups did not reach statistical significance (P = .0894). CONCLUSIONS: The incidence of thrombotic events in patients who underwent percutaneous renal cryoablation in this study was not significantly different than a comparable cohort who underwent surgical PN during the same time period.