Canadian Association of Radiologists consensus guidelines for the prevention of contrast-induced nephropathy: update 2012.

PURPOSE: Contrast-induced acute kidney injury or contrast-induced nephropathy (CIN) is a significant complication of intravascular contrast medium (CM). These guidelines are intended as a practical approach to risk stratification and prevention. The major risk factor that predicts CIN is pre-existing chronic kidney disease. METHODS: Members of the committee represent radiologists and nephrologists across Canada. The previous guidelines were reviewed, and an in-depth up-to-date literature review was carried out. RESULTS: A serum creatinine level (SCr) should be obtained, and an estimated glomerular filtration rate (eGFR) should be calculated within 6 months in the outpatient who is stable and within 1 week for inpatients and patients who are not stable. Patients with an eGFR of ≥ 60 mL/min have an extremely low risk of CIN. The risk of CIN after intra-arterial CM administration appears be at least twice that after intravenous administration. Fluid volume loading remains the single most important measure, and hydration regimens that use sodium bicarbonate or normal saline solution should be considered for all patients with GFR < 60 mL/min who receive intra-arterial contrast and when GFR < 45 mL/min in patients who receive intravenous contrast. Patients are most at risk for CIN when eGFR < 30 mL/min. Additional preventative measures include the following: avoid dehydration, avoid CM when appropriate, minimize CM volume and frequency, avoid high osmolar CM, and discontinue nephrotoxic medications 48 hours before administration of CM.

The mysterious organ. Spectrum of focal lesions within the splenic parenchyma: cross-sectional imaging with emphasis on magnetic resonance imaging.

Incidental splenic lesions are frequently encountered at imaging performed for unrelated causes. Splenic cysts, hemangiomas, and lymphomatous involvement are the most frequently encountered entities. Computed tomography and sonography are commonly used for initial evaluation with magnetic resonance imaging reserved as a useful problem-solving tool for characterizing atypical and uncommon lesions. The value of magnetic resonance imaging lies in classifying these lesions as either benign or malignant by virtue of their signal-intensity characteristics on T1- and T2-weighted imaging and optimal depiction of internal hemorrhage. Dynamic contrast-enhanced sequences may improve the evaluation of focal splenic lesions and allow characterization of cysts, smaller hemangiomas, and hamartomas. Any atypical or unexplained imaging feature related to an incidental splenic lesion requires additional evaluation and/or follow-up. Occasionally, biopsy or splenectomy may be required for definitive assessment given that some of tumours may demonstrate uncertain biologic behavior.

Leiomyomas beyond the uterus: unusual locations, rare manifestations.

Uterine leiomyomas affect 20%-30% of women older than 35 years. Extrauterine leiomyomas are rarer, and they present a greater diagnostic challenge: These histologically benign tumors, which originate from smooth muscle cells, usually arise in the genitourinary tract (in the vulva, ovaries, urethra, and urinary bladder) but may arise in nearly any anatomic site. In addition, unusual growth patterns may be seen, including benign metastasizing leiomyoma, disseminated peritoneal leiomyomatosis, intravenous leiomyomatosis, parasitic leiomyoma, and retroperitoneal growth. In the presence of such a pattern, a synchronous uterine leiomyoma or a previous hysterectomy for removal of a primary uterine tumor may be indicative of the diagnosis. However, some extrauterine leiomyomas may mimic malignancies, and serious diagnostic errors may result. The most useful modalities for detecting extrauterine leiomyomas are ultrasonography, computed tomography, and magnetic resonance (MR) imaging. The superb contrast resolution and multiplanar capabilities of MR imaging make it particularly valuable for characterizing these tumors, which usually show low signal intensity similar to that of smooth muscle on T2-weighted images. The radiologist's recognition of this and other characteristic features may help steer the clinician toward timely, appropriate management and away from unnecessary, potentially harmful treatment.

Mucinous neoplasms of the appendix: a current comprehensive clinicopathologic and imaging review.

Mucinous neoplasms of the appendix are a heterogeneous group of neoplasms ranging from simple mucoceles to complex pseudomyxoma peritonei. Considerable controversy exists on their pathologic classification and nomenclature. Clear understanding of the histopathologic diversity of these neoplasms helps in establishing proper communication between the radiologist, the pathologist and the surgeon. In this article, we present a brief discussion of the current taxonomy and nomenclature of mucinous neoplasms of the appendix followed by a review of their imaging features. Important points including the significance of identifying extra-appendiceal mucin at imaging, the new classification of pseudomyxoma peritonei into low- and high-grade varieties and the significance of simultaneous ovarian and appendiceal neoplasms are highlighted.

Ultrasound, computed tomography, and magnetic resonance imaging of ovarian vein thrombosis in obstetrical and nonobstetrical patients.

Ovarian vein thrombosis is an uncommon clinical entity, most familiar to radiologists as a source of postpartum sepsis, which, if unrecognized and left untreated, has the potential for septic shock, pulmonary thromboembolism, and death. Ovarian vein thrombosis also occurs with other common inflammatory and malignant conditions in the nonobstetrical patient. This article reviews the pathophysiology, predisposing conditions, clinical findings, imaging features on ultrasonography, computed tomography, and magnetic resonance imaging of acute and chronic ovarian vein thrombosis and its appropriate clinical management.

Cross-sectional imaging of small bowel malignancies.

Small bowel malignancies are rare neoplasms, usually inaccessible to conventional endoscopy but detectable in many cases by cross-sectional imaging. Modern multidetector computed tomographies permit accurate diagnosis, complete pretreatment staging, and follow-up of these lesions. In this review, we describe the cross-sectional imaging features of the most frequent histologic subtypes of the small bowel malignancies.

Thinking beyond peritoneal carcinomatosis: imaging spectrum of unusual disseminated peritoneal entities.

Although peritoneal carcinomatosis is the most common entity involving the peritoneum diffusely, a vast array of unusual diseases may affect the peritoneal surfaces. These entities can be further categorized into infectious, neoplastic, and miscellaneous, and miscellaneous conditions. Cross-sectional imaging, including computed tomography and magnetic resonance imaging are excellent modalities for further characterization of these unusual diseases. For some of the conditions, imaging-specific is achievable. For others, the diagnosis can be favored when clinical and/or cross-sectional features coexist.

Canadian Association of Radiologists: consensus guidelines for the prevention of contrast-induced nephropathy.

The development of acute renal failure significantly complicates intravascular contrast medium (CM) use and is linked with high morbidity and mortality. The increasing use of CM, an aging population, and an increase in chronic kidney disease (CKD) will result in an increased incidence of contrast-induced nephropathy (CIN)-unless preventive measures are used. The Canadian Association of Radiologists has developed these guidelines as a practical approach to risk stratification and prevention of CIN. The major risk factor predicting CIN is preexisting CKD, which can be predicted from the glomerular filtration rate (GFR). In terms of being an absolute measure, serum creatinine (SCr) is an unreliable measure of renal function. Patients with GFR >60 mL/min have a very low risk of CIN, and preventive measures are generally unnecessary. When GFR is <60 mL/min, preventive measures should be instituted. The risk of CIN is greatest in patients with GFR <30 mL/min. Preventive measures: Alternative imaging that does not require CM should be considered. Fluid volume loading is the single most important protective measure. Nephrotoxic medications should be discontinued 48 hours prior to the study. CM volume and frequency of administration should be minimized, but satisfactory image quality should still be maintained. High-osmolar contrast should be avoided in patients with renal impairment. There is some evidence to suggest that iso-osmolar contrast reduces the risk of CIN among patients with renal impairment, but further study is necessary to determine whether iso-osmolar contrast is superior to low-osmolar contrast. Acetylcysteine (AC) has been advocated to reduce the incidence of CIN; however, not all studies have shown a benefit, and it is difficult to formulate evidence-based recommendations at this time. Its use may be considered in high-risk patients but is not considered mandatory.