Matthew P. Schenker

Interrelation of Coronary Calcification, Myocardial Ischemia, and Outcomes in Patients With Intermediate Likelihood of Coronary Artery Disease A Combined Positron Emission Tomography/Computed Tomography Study

Background— Although the value of coronary artery calcium (CAC) for atherosclerosis screening is gaining acceptance, its efficacy in predicting flow-limiting coronary artery disease remains controversial, and its incremental prognostic value over myocardial perfusion is not well established. Methods and Results— We evaluated 695 consecutive intermediate-risk patients undergoing combined rest-stress rubidium 82 positron emission tomography (PET) perfusion imaging and CAC scoring on a hybrid PET-computed tomography (CT) scanner. The frequency of abnormal scans among patients with a CAC score ≥400 was higher than that in patients with a CAC score of 1 to 399 (48.5% versus 21.7%, P<0.001). Multivariate logistic regression supported the concept of a threshold CAC score ≥400 governing this relationship (odds ratio 2.91, P<0.001); however, the frequency of ischemia among patients with no CAC was 16.0%, and its absence only afforded a negative predictive value of 84.0%. Risk-adjusted survival analysis demonstrated a stepwise increase in event rates (death and myocardial infarction) with increasing CAC scores in patients with and without ischemia on PET myocardial perfusion imaging. Among patients with normal PET myocardial perfusion imaging, the annualized event rate in patients with no CAC was lower than in those with a CAC score ≥1000 (2.6% versus 12.3%, respectively). Likewise, in patients with ischemia on PET myocardial perfusion imaging, the annualized event rate in those with no CAC was lower than among patients with a CAC score ≥1000 (8.2% versus 22.1%). Conclusions— Although increasing CAC content is generally predictive of a higher likelihood of ischemia, its absence does not completely eliminate the possibility of flow-limiting coronary artery disease. Importantly, a stepwise increase occurs in the risk of adverse events with increasing CAC scores in patients with and without ischemia on PET myocardial perfusion imaging.

Upper gastrointestinal hemorrhage and transcatheter embolotherapy: clinical and technical factors impacting success and survival.

PURPOSE To identify clinical and technical factors influencing the outcome of transcatheter embolotherapy for nonvariceal upper gastrointestinal (GI) hemorrhage and to quantify the impact of successful intervention on patient survival. MATERIALS AND METHODS A retrospective review was performed of all patients (n = 163) who underwent arterial embolization for acute upper GI hemorrhage at a university hospital over an 11.5-year period. Clinical success was defined as target area devascularization that resulted in the clinical cessation of bleeding and stabilization of hemoglobin level. The clinical condition of each patient at intervention was defined by history, laboratory examination, and two composite indicator variables. With use of logistic regression, the dependent variable, clinical success, was modeled on two categories of clinical and technical variables. A final model regressed patient survival on clinical success and other clinical variables. RESULTS None of the procedural variables analyzed had a significant influence on clinical success. Several clinical variables did impact clinical success, including multiorgan system failure (OR, 0.36; P =.030), coagulopathy (OR, 0.36; P =.026), and bleeding subsequent to trauma (OR, 7.1; P =.040) or invasive procedures (OR, 6.5; P =.009). Regardless of their clinical condition at intervention, patients who underwent clinically successful embolization were 13.3 times more likely to survive than those who had an unsuccessful procedure (CI, 4.54-39.2; P =.000). Nevertheless, patients with multiorgan system failure were 17.5 times more likely to die, independent of the outcome of the procedure (CI, 0.014-0.229; P =.000). CONCLUSION Arresting nonvariceal upper GI hemorrhage with transcatheter embolotherapy has a large positive effect on patient survival, independent of clinical condition or demonstrable extravasation at intervention. Aggressive treatment with transcatheter embolotherapy is advisable in patients with acute nonvariceal upper GI hemorrhage.

Gadolinium Arteriography Complicated by Acute Pancreatitis and Acute Renal Failure

Editor: Several studies have supported the intravenous use of gadolinium as a paramagnetic contrast agent with a favorable safety profile (1,2). The relative safety of gadolinium-based contrast agents over iodine-based contrast agents in patients with renal insufficiency is also well established (3–5). Recently, however, reports of severe adverse reactions to standard doses of gadolinium have surfaced (6,7). Adding to this growing body of literature, we report a case of acute pancreatitis and acute renal failure after the administration of a gadoliniumbased contrast agent for iliac arteriography in a patient with diabetes mellitus and chronic renal insufficiency. A 68-year-old woman with long-standing bilateral lower extremity claudication was admitted to the interventional radiology service for right iliac artery stent placement. Preoperative MR angiography demonstrated a 90% ostial stenosis of the right common iliac artery and occlusion of the left common iliac artery. The patient also had a history of hypertension, hyperlipidemia, diabetes mellitus, and chronic renal insufficiency (creatinine 5 3.8 mg/dL). Given the patient’s baseline renal insufficiency and the attendant risk of nephrotoxicity from an iodine-based contrast agent, arteriography was performed with a gadolinium contrast agent, gadodiamide (Omniscan; Nycomed-Amersham, Princeton, NJ). Arteriography confirmed the presence of a critical (90%) ostial stenosis of the right common iliac artery. The patient received intravenous conscious sedation consisting of 1 mg of midazolam and 100 mg of fentanyl citrate. A total of 6,000 U of intravenous heparin was given to induce systemic anticoagulation before intervention. Subsequently, angioplasty and stent placement across the ostial lesion of the right common iliac artery were performed without immediate complication. Six hours after the procedure, the patient reported nausea, mild epigastric pain radiating to the back, and two episodes of vomiting. The patient received 10 mg of intravenous perchlorperazine, with transient improvement. Eleven hours after the procedure, the patient again reported epigastric discomfort and received 80 mg of oral simethicone, with minimal relief. Amylase and lipase levels at this time were noted to be 246 U/L and 1,314 U/L, respectively (laboratory normal ranges: amylase, 0–140 U/L; lipase, 0–200 U/L). Laboratory measurements obtained the next morning showed an increase in amylase and lipase to 684 U/L and 1,646 U/L. Results of liver function tests were within the reference range. A right upper quadrant ultrasound scan yielded findings that were within normal limits. The patient subsequently developed superimposed acute renal failure, electrolyte imbalance, and pulmonary edema, necessitating transfer to the intensive care unit. Microscopic urinalysis on the second postoperative day demonstrated muddy brown casts consistent with acute tubular necrosis. The patient’s respiratory status improved rapidly after aggressive diuresis, and she was stable for transfer to the renal service on the fifth postoperative day. With conservative management, her renal function improved and she never required dialysis. Her pancreatitis also resolved, without any further complications, and she was discharged from the hospital on the tenth postoperative day. In view of its relative safety in the setting of renal insufficiency, gadolinium is increasingly being used as an alternative contrast agent in interventional radiology. Despite its safety, however, there have been several recent reports of adverse events associated with gadolinium administration. Specifically, case reports of acute renal failure after gadoteridol intraarterially and acute pancreatitis after intravenous gadolinium-DTPA have surfaced (6,7). This case adds to a growing body of evidence that pancreatitis and renal failure are potential complications associated with gadolinium administration. To our knowledge, this is the first report of both acute pancreatitis and acute renal failure occurring in the same patient after a single administration of intraarterial gadolinium. While this case offers no definitive answers, it does suggest that further study of gadolinium dosing and adverse reactions in both animals and humans is necessary. There is currently no recommendation for the maximum safe dose of gadolinium, nor is there a minimum recommended creatinine clearance below which gadolinium should not be administered. Until such limits are established, care should be taken when administering large doses of gadolinium compounds.

Thoracic Duct Embolization and Disruption for Treatment of Chylous Effusions: Experience with 105 Patients

PURPOSE To review the indications, technical approach, and clinical outcomes of thoracic duct embolization (TDE) and thoracic duct disruption (TDD) in patients with symptomatic chylous effusions. MATERIALS AND METHODS A total of 105 patients who underwent 120 consecutive TDE/TDD procedures were retrospectively reviewed. Data including cause of effusion, procedural technique, and pre- and postprocedural effusion volume were analyzed. Technical and clinical success were evaluated for each procedure, with technical success defined as successful interruption of the thoracic duct by embolization or needle disruption and clinical success defined as resolution of effusion without surgical intervention. RESULTS The technical success rate was 79% (95 of 120); 53 TDEs were performed, resulting in a 72% clinical success rate (n = 38), whereas 42 TDDs showed a 55% clinical success rate (n = 23; P = .13). Procedures to treat postpneumonectomy chylous effusions had a success rate of 82% (14 of 17), compared with 47% (nine of 19) in postpleurectomy subjects (P < .05). Clinically successful cases had lower 24-, 48-, and 72-hour postprocedural effusion volumes versus clinically unsuccessful cases (P < .05), as well as greater rates of reduction in effusion volume at these time points (P < .05). Clinical success rate in subjects with traumatic effusions was higher than in subjects with nontraumatic effusions (62% [60 of 97] vs 13% [one of eight]; P < .05), and 6.7% of subjects (n = 7) experienced minor complications. CONCLUSIONS TDE and TDD are safe and effective minimally invasive treatments for traumatic thoracic duct injuries. In the present series, factors affecting procedural success included etiology of effusion, postprocedural effusion volume, and rate of postprocedural effusion volume reduction.

ACR Appropriateness Criteria® on Suspected Lower Extremity Deep Vein Thrombosis

Lower extremity deep vein thrombosis (DVT) is a common clinical concern, with an incidence that increases with advanced age. DVT typically begins below the knee but may extend proximally and result in pulmonary embolism. Pulmonary embolism can occur in 50% to 60% of patients with untreated DVT and can be fatal. Although clinical examination and plasma d-dimer blood evaluation can often predict the presence of DVT, imaging remains critical for the diagnostic confirmation and treatment planning of DVT. Patients with above-the-knee or proximal DVT have a high risk for pulmonary embolism and are recommended to receive anticoagulation therapy. On the other hand, patients with below-the-knee or distal DVT rarely experience pulmonary embolism, and anticoagulation therapy in these patients remains controversial. However, one sixth of patients with distal DVT may experience extension of their thrombus above the knee and therefore are recommended to undergo serial imaging assessment at 1 week to exclude proximal DVT extension if anticoagulation therapy is not initiated. Ultrasound is the preferred imaging method for evaluation of patients with newly suspected lower extremity DVT. Magnetic resonance and CT venography can be especially helpful for the evaluation of suspected DVT in the pelvis and thigh. Contrast x-ray venography, the historic gold standard for DVT assessment, is now less commonly performed and primarily reserved for patients with more complex presentations such as those with suspected recurrent acute DVT.

ACR Appropriateness Criteria® Imaging for Transcatheter Aortic Valve Replacement

Although aortic valve replacement is the definitive therapy for severe aortic stenosis, almost half of patients with severe aortic stenosis are unable to undergo conventional aortic valve replacement because of advanced age, comorbidities, or prohibitive surgical risk. Treatment options have been recently expanded with the introduction of catheter-based implantation of a bioprosthetic aortic valve, referred to as transcatheter aortic valve replacement. Because this procedure is characterized by lack of exposure of the operative field, image guidance plays a critical role in preprocedural planning. This guideline document evaluates several preintervention imaging examinations that focus on both imaging at the aortic valve plane and planning in the supravalvular aorta and iliofemoral system. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria® on Upper Gastrointestinal Bleeding

Upper gastrointestinal bleeding is a significant cause of morbidity and mortality, affecting 36 to 48 per 100,000 persons annually. Aggressive resuscitation and upper endoscopy remain the cornerstones of therapy; however, in cases refractory to endoscopic diagnosis and management, radiology plays an increasingly vital and often lifesaving role, thanks to improvements in both imaging and interventional techniques. The various etiologies of upper gastrointestinal bleeding are discussed along with specific management recommendations based on an extensive literature review of current radiographic methods.

ACR Appropriateness Criteria Imaging in the Diagnosis of Thoracic Outlet Syndrome

Thoracic outlet syndrome is a clinical entity characterized by compression of the neurovascular bundle, and may be associated with additional findings such as venous thrombosis, arterial stenosis, or neurologic symptoms. The goal of imaging is to localize the site of compression, the compressing structure, and the compressed organ or vessel, while excluding common mimics. A literature review is provided of current indications for diagnostic imaging, with discussion of potential limitations and benefits of the respective modalities. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. In this document, we provided guidelines for use of various imaging modalities for assessment of thoracic outlet syndrome.

ACR Appropriateness Criteria® Suspected Upper Extremity Deep Vein Thrombosis

Upper-extremity venous thrombosis often presents as unilateral arm swelling. The differential diagnosis includes lesions compressing the veins and causing a functional venous obstruction, venous stenosis, an infection causing edema, obstruction of previously functioning lymphatics, or the absence of sufficient lymphatic channels to ensure effective drainage. The following recommendations are made with the understanding that venous disease, specifically venous thrombosis, is the primary diagnosis to be excluded or confirmed in a patient presenting with unilateral upper-extremity swelling. Contrast venography remains the best reference-standard diagnostic test for suspected upper-extremity acute venous thrombosis and may be needed whenever other noninvasive strategies fail to adequately image the upper-extremity veins. Duplex, color flow, and compression ultrasound have also established a clear role in evaluation of the more peripheral veins that are accessible to sonography. Gadolinium contrast-enhanced MRI is routinely used to evaluate the status of the central veins. Delayed CT venography can often be used to confirm or exclude more central vein venous thrombi, although substantial contrast loads are required. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Interventional radiology and anesthesia.

Interventional radiology (IR) encompasses a broad and expanding array of image-guided, minimally invasive therapies that are essential to the practice of modern medicine. The growth and diversity of these non-OR procedures presents unique challenges and opportunities to anesthesiologists and interventional radiologists alike. Collaborative action has led to better patient care and quality management. This discussion considers some angiographic and cross-sectional IR procedures in more detail and comments on some of the anesthesia choices and considerations. In addition, specific concerns regarding anesthesia in the area of IR are reviewed.