Magnetic resonance imaging of pancreatic metastases from renal cell carcinoma.

Pancreatic metastases are rare but are thought to be most commonly from renal cell carcinoma (RCC). These metastases can present many years after the initial tumor is resected, and accordingly, these patients require prolonged imaging follow-up. Although the computed tomographic findings of these metastases have been extensively reviewed in the literature, little has been written about the magnetic resonance imaging appearance of these metastases. Pancreatic metastases from RCC are typically T1 hypointense and T2 hyperintense. After intravenous administration of gadolinium, they are typically hypervascular and less commonly hypovascular. Chemical shift and diffusion-weighted imaging can aid in the diagnosis of these metastases.

Beyond hepatic hemangiomas: the diverse appearances of gastrointestinal and genitourinary hemangiomas.

Hemangiomas are common lesions, best known for their appearance in the liver. Their appearance in less common locations, such as the gastrointestinal and genitourinary tracts, is less well known. We will review the typical and atypical appearance of hemangiomas in these locations on sonography, CT, and MRI.

Diffusion-weighted MR imaging of solid and cystic lesions of the pancreas.

Diffusion-weighted magnetic resonance (MR) imaging is increasingly used in the detection and characterization of pancreatic lesions. Diffusion-weighted imaging may provide additional information to radiologists evaluating patients who have cystic or solid neoplasms of the pancreas. Because of greater freedom of motion of water molecules in fluid-rich environments, simple cysts in the pancreas have higher signal intensity on diffusion-weighted images with a b value of 0 sec/mm2 and lower signal intensity on high-b-value images. High apparent diffusion coefficient (ADC) values can be obtained on ADC maps because of the T2 "shine-through" effect. In contrast, solid neoplasms of the pancreas show increased signal intensity relative to the pancreas on diffusion-weighted images with a b value of 0 sec/mm2 and relatively high signal intensity on high-b-value images. Diffusion-weighted imaging can help detect solid pancreatic neoplasms with extremely dense cellularity or extracellular fibrosis by demonstrating significantly low ADC values, and these neoplasms may be better detected on diffusion-weighted MR images because of better contrast, although the resolution is generally worse. However, diffusion-weighted imaging may not be capable of helping definitively characterize solid lesions as inflammatory or neoplastic because of an overlap in ADC values between the two types. For example, it is difficult to distinguish poorly differentiated pancreatic adenocarcinoma from mass-forming pancreatitis at diffusion-weighted imaging because of similarly low ADC values attributed to dense fibrosis.

Pathophysiological changes in calf muscle predict mobility loss at 2-year follow-up in men and women with peripheral arterial disease.

BACKGROUND: Associations of pathophysiological calf muscle characteristics with functional decline in people with lower extremity peripheral arterial disease are unknown. METHODS AND RESULTS: Three hundred seventy participants with peripheral arterial disease underwent baseline measurement of calf muscle area, density, and percent fat with the use of computed tomography. Participants were followed up annually for 2 years. The outcome of mobility loss was defined as becoming unable to walk 1/4 mile or walk up and down 1 flight of stairs without assistance among those without baseline mobility limitations. Additional outcomes were > or =20% decline in 6-minute walk distance and becoming unable to walk for 6 minutes continuously among participants who walked continuously for 6 minutes at baseline. With adjustment for age, sex, race, body mass index, the ankle-brachial index, smoking, physical activity, relevant medications, and comorbidities, lower calf muscle density (P for trend <0.001) and lower calf muscle area (P for trend=0.039) were each associated with increased mobility loss rates. Compared with participants in the highest baseline tertiles, participants in the lowest tertile of calf muscle percent fat had a hazard ratio of 0.18 for incident mobility loss (95% confidence interval, 0.06 to 0.55; P=0.003), and participants in the lowest tertile of muscle density had a 3.50 hazard ratio for incident mobility loss (95% confidence interval, 1.28 to 9.57; P=0.015). No significant associations of calf muscle characteristics with 6-minute walk outcomes were observed. CONCLUSIONS: Our findings suggest that interventions to prevent mobility loss in peripheral arterial disease should focus on reversing pathophysiological findings in calf muscle.

Computed tomography and magnetic resonance imaging features of lesions of the renal medulla and sinus.

The kidneys can harbor a wide variety of lesions, many of which can be visualized by computed tomography and magnetic resonance imaging. In this article, the pertinent renal anatomic relationships as well as the histologic composition and function of the renal medulla and sinus are reviewed. Additionally, computed tomography and magnetic resonance imaging features of renal sinus and medullary lesions in adult patients are presented. This article reviews the salient imaging features of various malignant, benign neoplastic, and nonneoplastic lesions of the sinus and medulla.

Asymptomatic peripheral arterial disease is associated with more adverse lower extremity characteristics than intermittent claudication.

BACKGROUND: This study assessed functional performance, calf muscle characteristics, peripheral nerve function, and quality of life in asymptomatic persons with peripheral arterial disease (PAD). METHODS AND RESULTS: PAD participants (n=465) had an ankle brachial index <0.90. Non-PAD participants (n=292) had an ankle brachial index of 0.90 to 1.30. PAD participants were categorized into leg symptom groups including intermittent claudication (n=215) and always asymptomatic (participants who never experienced exertional leg pain, even during the 6-minute walk; n=72). Calf muscle was measured with computed tomography. Analyses were adjusted for age, sex, race, ankle brachial index, comorbidities, and other confounders. Compared with participants with intermittent claudication, always asymptomatic PAD participants had smaller calf muscle area (4935 versus 5592 mm(2); P<0.001), higher calf muscle percent fat (16.10% versus 9.45%; P<0.001), poorer 6-minute walk performance (966 versus 1129 ft; P=0.0002), slower usual-paced walking speed (P=0.0019), slower fast-paced walking speed (P<0.001), and a poorer Short-Form 36 Physical Functioning score (P=0.016). Compared with an age-matched, sedentary, non-PAD cohort, always asymptomatic PAD participants had smaller calf muscle area (5061 versus 5895 mm(2); P=0.009), poorer 6-minute walk performance (1126 versus 1452 ft; P<0.001), and poorer Walking Impairment Questionnaire speed scores (40.87 versus 57.78; P=0.001). CONCLUSIONS: Persons with PAD who never experience exertional leg symptoms have poorer functional performance, poorer quality of life, and more adverse calf muscle characteristics compared with persons with intermittent claudication and a sedentary, asymptomatic, age-matched group of non-PAD persons.

Elevated levels of inflammation, d-dimer, and homocysteine are associated with adverse calf muscle characteristics and reduced calf strength in peripheral arterial disease.

OBJECTIVES: This study determined whether increased levels of inflammatory blood markers, D-dimer, and homocysteine were associated with smaller calf skeletal muscle area, increased calf muscle percent fat, reduced calf muscle density, and poorer calf strength in persons with lower extremity peripheral arterial disease (PAD). BACKGROUND: Elevated levels of inflammatory markers and D-dimer are associated with greater functional impairment and functional decline in persons with PAD. Mechanisms of these associations are unknown. METHODS: Participants were 423 persons with PAD. Calf muscle area, percent fat, and density were measured with computed tomography. Physical activity levels were measured objectively over 7 days with the Caltrac (Muscle Dynamics Fitness Network, Inc., Rocklin, California) vertical accelerometer. Isometric plantarflexion strength was measured. Analyses were adjusted for age, gender, race, comorbidities, the ankle-brachial index, and other potential confounders. RESULTS: Higher levels of D-dimer (p = 0.014), C-reactive protein (CRP) (p = 0.002), interleukin (IL)-6 (p < 0.001), and soluble vascular cellular adhesion molecule (sVCAM)-1 (p = 0.008) were associated with smaller calf muscle area. Higher sVCAM-1 (p = 0.004) and IL-6 (p = 0.017) were associated with higher calf muscle percent fat. Higher D-dimer (p < 0.001), sVCAM-1 (p < 0.001), and homocysteine (p = 0.014) were associated with lower calf muscle density. These associations were generally unchanged after additional adjustment for physical activity. Higher sVCAM-1 (p = 0.013) was associated with lower calf strength. CONCLUSIONS: These data show, for the first time, that higher levels of inflammation, D-dimer, and homocysteine are associated with more adverse calf muscle characteristics in persons with PAD. These associations may contribute to previously established associations between elevated biomarkers and functional impairment and functional decline in PAD.

Physical activity, walking exercise, and calf skeletal muscle characteristics in patients with peripheral arterial disease.

OBJECTIVE: This cross-sectional study was set in an academic medical center and conducted to identify associations of physical activity level and walking exercise frequency with calf skeletal muscle characteristics in individuals with lower extremity peripheral arterial disease (PAD). METHODS: Calf muscle characteristics in 439 men and women with PAD were measured with computed tomography at 66.67% of the distance between the distal and proximal tibia. Physical activity was measured continuously during 7 days with a vertical accelerometer. Patient report was used to determine the number of blocks walked during the past week and walking exercise frequency. Results were adjusted for age, sex, race, comorbidities, ankle-brachial index, body mass index, smoking, and other confounders. RESULTS: For both objective and subjective measures, more physically active PAD participants had higher calf muscle area and muscle density. Calf muscle area across tertiles of accelerometer-measured physical activity were first activity tertile, 5071 mm(2); second activity tertile: 5612 mm(2); and third activity tertile, 5869 mm(2) (P < .001). Calf muscle density across tertiles of patient-reported blocks walked during the past week were first activity tertile, 31.4 mg/cm(3); second activity tertile, 33.0 mg/cm(3); and third activity tertile, 33.8 mg/cm(3) (P < .001). No significant associations were found between walking exercise frequency and calf muscle characteristics. CONCLUSION: Among participants with PAD, higher physical activity levels, measured by accelerometer and by patient-reported blocks walked per week, were associated with more favorable calf muscle characteristics. In contrast, more frequent patient-reported walking exercise was not associated with more or less favorable calf muscle characteristics. Results suggest that clinicians should encourage their patients to increase their walking activity during daily life.

Lower extremity ischemia, calf skeletal muscle characteristics, and functional impairment in peripheral arterial disease.

OBJECTIVES: To determine whether lower ankle brachial index (ABI) levels are associated with lower calf skeletal muscle area and higher calf muscle percentage fat in persons with and without lower extremity peripheral arterial disease (PAD). DESIGN: Cross-sectional. SETTING: Three Chicago-area medical centers. PARTICIPANTS: Four hundred thirty-nine persons with PAD (ABI<0.90) and 265 without PAD (ABI 0.90-1.30). MEASUREMENTS: Calf muscle cross-sectional area and the percentage of fat in calf muscle were measured using computed tomography at 66.7% of the distance between the distal and proximal tibia. Physical activity was measured using an accelerometer. Functional measures included the 6-minute walk, 4-meter walking speed, and the Short Physical Performance Battery (SPPB). RESULTS: Adjusting for age, sex, race, comorbidities, and other potential confounders, lower ABI values were associated with lower calf muscle area (ABI<0.50, 5,193 mm(2); ABI 0.50-0.90, 5,536 mm(2); ABI 0.91-1.30, 5,941 mm(2); P for trend<.001). These significant associations remained after additional adjustment for physical activity. In participants with PAD, lower calf muscle area in the leg with higher ABI was associated with significantly poorer performance in usual- and fast-paced 4-meter walking speed and on the SPPB, adjusting for ABI, physical activity, percentage fat in calf muscle, muscle area in the leg with lower ABI, and other confounders (P<.05 for all comparisons). CONCLUSION: These data support the hypothesis that lower extremity ischemia has a direct adverse effect on calf skeletal muscle area. This association may mediate previously established relationships between PAD and functional impairment.

CT diagnosis of chyluria after partial nephrectomy.

OBJECTIVE: The purpose of this study was to describe the CT diagnosis of chyluria after partial nephrectomy. CONCLUSION: Fat in the bladder can be identified on CT after partial nephrectomy. This finding is caused by chyluria secondary to lymphatic injury and should not be mistaken for other abnormalities. Our study population did not need treatment of chyluria.

Unexplained renal colic: what is the utility of IV contrast?

PURPOSE: The aim of this study was to evaluate the benefit of intravenous (IV) contrast in patients with suspected renal colic and unremarkable unenhanced MDCT. MATERIALS AND METHODS: One thousand two hundred and four patients with suspected ureterolithiasis were evaluated with unenhanced MDCT. Seven hundred and eight patients that had additional imaging following IV contrast were our study group. RESULTS: Of the patients, 9.4% (67/708) had abnormalities seen only on contrast-enhanced exams. In 53.1% (376/708) of the patients, no additional finding was identified after IV contrast. CONCLUSION: IV contrast in patients with renal colic is rarely helpful.

Coronal imaging to assess urinary tract stone size.

PURPOSE: Urinary tract stones are typically measured using axial images from computerized tomography (CT). Such images provide a precise measurement of stone length and width. However, cephalocaudad dimensions can be difficult to determine from axial images. Coronal reconstructions, which can more accurately measure cephalocaudad dimensions, are seldom used to measure stones. We determined if coronal reconstructions could aid in more precisely determining stone size. MATERIALS AND METHODS: CT in patients who had undergone CT to evaluate urolithiasis at our institution during the 9-month period of January 2001 to September 2001 were reviewed. Length and width were measured using axial images, and cephalocaudad length and width were measured using coronal reconstructions. Cephalocaudad length was also estimated from axial images. Total area was calculated from axial and coronal reconstructions. The paired t test was used to assess statistical significance. RESULTS: The CT images of 102 patients with a total of 151 stones had undergone coronal reconstructions and, thus, were included in the study. Mean area in the axial and coronal reconstruction groups was 22.23 and 31.29 mm, respectively. Mean greatest axial dimension (length or width) was 4.87 mm and mean greatest coronal dimension (cephalocaudad length) was 6.51 mm. Cephalocaudad length estimated from axial images was 8.8 mm. Differences for all 3 of these comparisons (axial vs coronal area, greatest axial vs coronal dimension and estimated vs actual cephalocaudad length) proved to be statistically significant (p <0.0001). CONCLUSIONS: While urinary tract stones have typically been measured using axial images, coronal images provide a different impression of stone size. These data demonstrate that examining only axial images provides an inaccurate measure of stone size. We suggest that coronal images should also be used to measure more accurately stone size, which is critical for clinical decision making.