Early chest computed tomography in adult acute severe community-acquired pneumonia patients treated in the intensive care unit

BACKGROUND

The value of early chest computed tomography (CT) was evaluated among severe community-acquired pneumonia (SCAP) patients.

METHODS

The study population consisted of 65 of 457 SCAP patients with concomitant chest CT and radiograph performed within 48 h of ICU admission. Each image pair was re-evaluated by two radiologists. The type of pneumonia, the presence of pleural fluid and atelectasis were assessed. Therapeutic and diagnostic procedures induced by CT results were analysed together with clinical, microbiological and outcome data.

RESULTS

Alveolar pneumonia was observed in 72.3% of patients by radiograph and in 75.4% of patients by CT. Pleural fluid was detected via chest radiograph and CT in 17 (26.2%) and 41 cases (63.1%), (P < 0.001) and atelectasis in 10 (15.4%) and 22 cases (33.8%), (P = 0.002), respectively. In 34 patients (52.3%), the CT revealed 38 new findings (58.5%) not shown in plain chest radiograph. Out of these 34 patients, therapeutic interventions or procedures were performed in 26 (76.5%). The number of infected lobes correlated negatively with the lowest PaO2 /FiO2 ratio (ρ = -0.326, P = 0.008) for chest CT scans.

CONCLUSION

Compared with chest radiograph, chest CT generated new findings in nearly 60% of SCAP patients, leading to new procedures or changes in medical treatment in nearly 75% of those patients. Chest CT better describes the pulmonary involvement and severity of oxygenation disorder compared to a plain chest radiograph.

Reproducibility of imaging human knee cartilage by delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) at 1.5 Tesla

OBJECTIVE

The purpose of this study was to investigate the day-to-day reproducibility of the delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) measurement at different knee joint surfaces in healthy subjects at 1.5 Tesla (T).

METHODS

The dGEMRIC experiment was repeated for 10 asymptomatic volunteers three times with an average interval of 5 days between scans. The measurement was performed from a single sagittal slice through the center of the lateral femoral condyle and from the center of the patella in the axial plane. Cartilage was manually segmented into superficial, deep and full-thickness regions of interests (ROIs) at different topographical locations of the femur, tibia and patella. The reproducibility was evaluated separately for each ROI as well as for the entire bulk cartilage in the slice of each joint surface.

RESULTS

The reproducibility at various ROIs expressed by root-mean-square average coefficient of variation (CV(RMS)) ranged between 4.7-12.9%. Thirty out of thirty-three ROIs showed a CV(RMS) less than 10%. Intraclass correlation coefficient (ICC) ranged between 0.45 and 0.98. The CV(RMS) and ICC for bulk dGEMRIC were 4.2% and 0.95 for femur, 5.5% and 0.87 for tibia, and 4.8% and 0.97 for patella.

CONCLUSIONS

The dGEMRIC technique showed good day-to-day reproducibility, on the average 8% for small deep or superficial segments, 7% for full-thickness ROIs and 5% for bulk ROIs covering all visible cartilage in a single joint surface. We conclude that dGEMRIC imaging at field strength 1.5 T can be used as a reliable instrument for the assessment of articular cartilage when staff has been carefully trained.

Patellar cartilage lesions: comparison of magnetic resonance imaging and T2 relaxation-time mapping

PURPOSE

To evaluate the detection and the size of focal patellar cartilage lesions in T2 mapping as compared to standard clinical magnetic resonance imaging (MRI) at 1.5T.

MATERIAL AND METHODS

Fifty-five consecutive clinical patients referred to knee MRI were imaged both with a standard knee MRI protocol (proton-density-weighted sagittal and axial series, T2-weighted sagittal and coronal series, and T1-weighted coronal series) and with an axial multislice multi-echo spin-echo measurement to determine the T2 relaxation time of the patellar cartilage. MR images and T2 maps of patellar cartilage were evaluated for focal lesions. The lesions were evaluated for lesion width (mm), lesion depth (1/3, 2/3, or 3/3 of cartilage thickness), and T2 value (20-40 ms, 40-60 ms, or 60-80 ms) based on visual evaluation.

RESULTS

Altogether, 36 focal patellar cartilage lesions were detected from 20 human subjects (11 male, nine female, mean age 40+/-15 years). Twenty-eight lesions were detected both on MRI and T2 maps, while eight lesions were only visible on T2 maps. Cartilage lesions were significantly wider (P = 0.001) and thicker (P<0.001) on T2 maps as compared to standard knee MRI. Most lesions 27 had moderately (T2 40-60 ms) increased T2 values, while two lesions had slightly (T2 20-40 ms) and seven lesions remarkably (T2 60-80 ms) increased T2 relaxation times.

CONCLUSION

T2 mapping of articular cartilage is feasible in the clinical setting and may reveal early cartilage lesions not visible with standard clinical MRI.

Circumferential measurement of thoracic wall using a standard respiratory belt

Respiratory gating during imaging to reduce imaging artifacts involves the gathering of image data only at the end of the respiratory cycle. This is commonly performed by a pneumatic respiratory belt to monitor thoracic wall motion during respiration. Such gating has been used for magnetic resonance, computerized tomographic, and nuclear medicine imaging. The goal of this study was to measure the performance of a standard belt used for gating imaging studies. The standard respiratory belt system provided with the Magnetom 42 SP MRI scanner (Siemens AG, Erlangen, Germany) was selected. The belt was connected to a microcontroller-based pressure measurement unit that was connected to the standard RS-232C serial port of a computer. The signal was compared with that of a strain gauge respiration transducer. The response of the system was tested in vitro both for isometric and isotonic loading. The data measured from the pneumatic belt was linear with different weights of 50 to 1,400 grams with a coefficient of determination (R2) of 0.999. The system was linear for different amounts of stretching (R2 of 0.998) within the first 45 mm, which is enough for normal breathing. In vivo the pneumatic system seemed more accurate in measuring the constant stretching in apnea than the strain gauge respiratory belt. The results show that it is possible to use a standard pneumatic belt for accurate measurement of thoracic wall movement during imaging and for other purposes as well.