Prevalence and frequency of subchondral bone marrow edema in the lumbar facet joints of asymptomatic and symptomatic individuals.

OBJECTIVE: To prospectively compare the prevalence and frequency of subchondral bone marrow edema (BME) in the lumbar facet joints of low back pain patients and healthy subjects. MATERIALS AND METHODS: Lumbar magnetic resonance imaging (MRI) examinations were performed on 55 asymptomatic participants (18 men; age range 21-63; mean 36 ± 12 years; body mass index (BMI) range 16-31; mean 22.6 ± 3.2 kg/m2) and 79 low back pain patients (36 men; age range 18-77; mean 47 ± 14 years; BMI range 18-40; mean 27.8 ± 4.4 kg/m2). In both groups, facet joint subchondral BME signal was evaluated using T2-weighted STIR imaging, and facet joint osteoarthritis was characterized as mild, moderate, and severe. RESULTS: The BME signal was found in seven asymptomatic participants (12.7%) and 28 low back pain patients (35.4%) (P = 0.003). A significant portion of the patients (15.2%) presented more than one BME signal (P = 0.011). By pooling the ten facet joints of all subjects in each group, a significant difference in osteoarthritis grade distribution was observed between the two groups (P < 0.001). When adjusted for low back pain status, age, BMI, Modic type 1, disk herniation, and facet joint osteoarthritis maximal grade, only the latter was significantly associated with the facet joint BME signal (P < 0.001). CONCLUSION: Despite the higher prevalence and frequency of the BME signal in facet joints of low back pain patients compared to that in healthy subjects, the signal was found to be associated with the severity of the patients' osteoarthritis and not with their low back pain status.

Abdominal Attenuation Values on Virtual and True Unenhanced Images Obtained With Third-Generation Dual-Source Dual-Energy CT.

OBJECTIVE: The purpose of this study is to investigate the magnitude of differences between attenuation values measured on virtual unenhanced images and true unenhanced images obtained using third-generation dual-source dual-energy CT (DECT). SUBJECTS AND METHODS: A total of 83 patients requiring thoracoabdominal CT for cancer workup were included in this prospective study. CT examinations included true unenhanced acquisitions (tube potential, 120 kVp) and arterial and portal phase dual-energy CT (DECT) acquisitions (tube potential, 100 kVp and Sn 150 kVp [where Sn denotes the interposition of a tin filter in the high-energy beam]; tube current-exposure time product, 190 and 95 mAs). Virtual unenhanced images were created using two commercially available DECT postprocessing algorithms, one of which was designed to create liver images (hereafter referred to as VNC1 images) and the other of which was designed to create images of organs containing minor amounts of fat (hereafter referred to as VNC2 images). Attenuation values on the liver, spleen, paraspinal muscles, retroperitoneal fat, renal cortex and medulla, and gallbladder and bladder lumens were measured. RESULTS: The attenuation values of all tissues were significantly different between virtual unenhanced and true unenhanced images (p = < 0.001-0.042), except for the liver and spleen in the portal phase and muscles in both phases. When statistically significant, correlations between these differences and body mass index (weight in kilograms divided by the square of height in meters) depended on the tissue imaged and algorithm used. The percentage of cases in which these differences were 10 HU or greater was 1% for the liver and approximately 5% for the spleen and muscles, regardless of the algorithm and phase, but on VNC1 images it reached approximately 30% for the kidney, 70% for the gallbladder and bladder, and depending on the phase, 40-70% for fat. On VNC2 images, the percentage of cases in which these differences were 20 HU or greater was approximately 90% for fat. CONCLUSION: Abdominal virtual unenhanced images obtained with third-generation dual-source DECT still should not replace true unenhanced images because of substantial differences in attenuation measurements for fluid, fat, and renal tissues.

In Vivo Differentiation of Uric Acid Versus Non-Uric Acid Urinary Calculi With Third-Generation Dual-Source Dual-Energy CT at Reduced Radiation Dose.

OBJECTIVE: The objective of our study was to evaluate in vivo urinary calculus characterization with third-generation dual-source dual-energy CT (DECT) at reduced versus standard radiation dose. SUBJECTS AND METHODS: One hundred fifty-three patients requiring unenhanced CT for suspected or known urolithiasis were prospectively included in our study. They underwent two acquisitions at reduced-dose CT (90 kV and 50 mAsref; Sn150 kV and 31 mAsref, where Sn denotes the interposition of a tin filter in the high-energy beam) and standard-dose CT (90 kV and 50 mAsref; Sn150 kV and 94 mAsref). One radiologist interpreted the reduced-dose examinations before the standard-dose examinations during the same session. Among 103 patients (23 women, 80 men; mean age ± SD, 50 ± 15 years; age range, 18-82 years) with urolithiasis, dedicated DECT software measured the maximal diameter and CT numbers, calculated the DECT number ratio, and labeled with a color code each calculus visualized by the radiologist as uric acid (UA) or non-UA. Volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded. RESULTS: The radiologist visualized 279 calculi on standard-dose CT and 262 on reduced-dose CT; 17 calculi were missed on reduced-dose CT, all of which were ≤ 3 mm. Among the 262 calculi visualized at both doses, the CT number ratio was obtained with the software for 227 calculi and was not different between the doses (p = 0.093). Among these 262 calculi, 197 were labeled at both doses; 194 of the 197 labeled calculi were labeled with the same color code. Among the 65 remaining calculi, 48 and 61 (all ≤ 5 mm) were not labeled at standard-dose and reduced-dose CT (p = 0.005), respectively. At reduced-dose CT, the mean CTDIvol was 2.67 mGy and the mean DLP was 102.2 mGy × cm. CONCLUSION: With third-generation dual-source DECT, a larger proportion of calculi ≤ 5 mm are not characterized as UA or non-UA at a reduced dose.

Severe COPD exacerbation: CT features.

UNLABELLED: Abstract Objective: To describe CT features associated with severe exacerbations of Chronic Obstructive Pulmonary Disease (COPD). MATERIALS AND METHODS: In this prospective ethical-committee-approved study, 44 COPD patients (34 men, 10 women, age range 49-83 years) who provided written informed consent were included at the time of hospital admission for severe exacerbation. Pulmonary function tests (PFT) and chest CT scans were performed at admission and after resolution of the episode following a minimum of 4 weeks free of any acute symptom. For each CT scan, two radiologists independently scored 15 features in each lobe and side. CT features and PFT results were compared for exacerbation and control through Mac-Nemar tests and paired t-tests, respectively. RESULTS: Forced expiratory volume in 1 second and vital capacity improved significantly after exacerbation (p = 0.023 and 0.012, respectively). Bronchial wall thickening and lymphadenopathy were graded significantly higher at exacerbation than at control by both readers (p ranging from < 0.001 to 0.028). Other CT features were not observed during exacerbation, or were so only by one reader (p ranging from < 0.001 to 0.928). CONCLUSION: Only lymphadenopathy and bronchial wall thickening are CT features associated with severe COPD exacerbation, respectively in 25% and 50% of patients. Our findings do not advocate a role for CT in the routine work-up of patients with severe COPD exacerbation.