Detection and classification of focal liver lesions in patients with colorectal cancer: retrospective comparison of diffusion-weighted MR imaging and multi-slice CT

Objectives

To compare the diagnostic performance of diffusion-weighted MR imaging (DWI) with multi-slice CT (MS-CT) in the detection and classification of focal liver lesions in patients with colorectal cancer.

Methods

In a retrospective study 68 patients who underwent DWI at 1.5 T (b-values of 50, 300 and 600 s/mm²) and contrast-enhanced MS-CT were analysed by two radiologists blinded to the clinical results. Imaging results were correlated with intraoperative surgical and ultrasound findings (n = 24), imaging follow-up or PET (n = 44). Sensitivity of DWI and MS-CT in detection of focal liver lesions was compared on a per-lesion and a per-segment basis. Receiver operator-characteristic (ROC) curves to determine the diagnostic performance and the sensitivities of correctly identifying liver metastases on a segmental base were calculated.

Results

For lesion detection, DWI was significantly superior to MS-CT both on a per-lesion (difference in sensitivities for reader 1 and 2 22.65% and 19.06%, p < 0.0001) and a per-segment basis (16.86% and 11.76%, p < 0.0001). Especially lesions smaller than 10 mm were better detected with DWI compared to MS-CT (difference 41.10% and 29.45%, p < 0.0001). ROC-analysis showed superiority for lesions classification (p < 0.0001) of DWI (AUC: 0.949 and 0.951) as compared to MS-CT (AUC: 0.879 and 0.892, p < 0.0001 and p = 0.005). DWI was able to filter out metastatic segments with a higher sensitivity (88.2 and 86.5%) compared to MS-CT (68.0 and 67.4%, p < 0.0001 and p = 0.005, respectively).

Conclusion

Compared to MS-CT DWI is both more sensitive in the detection of liver lesions and more accurate in determining the extent of metastatic disease in patients with colorectal cancer and therefore might help to optimize therapeutic management in those patients.     

Split-bolus CT-urography using dual-energy CT: Feasibility, image quality and dose reduction

Purpose

To prospectively evaluate the feasibility of dual-energy (DE) split-bolus CT-urography (CTU) and the quality of virtual non-enhanced images (VNEI) and DE combined nephrographic-excretory phase images (CNEPI), and to estimate radiation dose reduction if true non-enhanced images (TNEI) could be omitted.

Patients and methods

Between August and September 2011, 30 consecutive patients with confirmed or suspected urothelial cancer or with hematuria underwent DE CT. Single-energy TNEI and DE CNEPI were obtained. VNEI was reconstructed from CNEPI. Image quality of CNEPI and VNEI was evaluated using a 5-point scale. The attenuation of urine in the bladder on TNEI and VNEI was measured. The CT dose index volume (CTDI (vol)) of the two scans was recorded.

Results

The mean image quality score of CNEPI and VNEI was 4.7 and 3.3, respectively. The mean differences in urine attenuation between VNEI and TNEI were 14 ± 15 [SD] and −16 ± 29 in the anterior and posterior parts of the bladder, respectively. The mean CTDI (vol) for TNEI and CNEPI was 11.8 and 10.9 mGy, respectively. Omission of TNEI could reduce the total radiation dose by 52%.

Conclusion

DE split-bolus CTU is technically feasible and can reduce radiation exposure; however, an additional TNEI scan is necessary when the VNEI quality is poor or quantitative evaluation of urine attenuation is required.     

Evaluation of suspected local recurrence in head and neck cancer: a comparison between PET and PET/CT for biopsy proven lesions

Background

¹⁸F-FDG PET has a high accuracy for re-staging of head and neck cancer. The purpose of this study was to determine whether the diagnostic accuracy can be further improved with integrated PET/CT.

Materials and methods

Forty-nine patients with a mean age of 59 ± 18 years were studied retrospectively. Histo-pathological verification was available either from complete tumor resection with or without lymph node dissection (n = 27) or direct endoscopic biopsy (n = 16) or ultrasound guided biopsy (n = 6). Two reviewers blinded to the pathological findings read all PET images in consensus. An experienced radiologist was added for the interpretation of the PET/CT images.

Results

Tissue verification was available for 110 lesions in 49 patients. Sixty-seven lesions (61%) were biopsy positive and 43 (39%) were negative for malignant disease. PET and PET/CT showed an overall accuracy for cancer detection of 84 and 88% (p = 0.06), respectively. Sensitivity and specificity for PET were 78 and 93% versus 84 (p = NS) and 95% (p = NS) with PET/CT. A patient-by-patient analysis yielded a sensitivity, specificity and accuracy for PET of 80, 56 and 76%, compared to 88% (p = NS), 78% (p = NS) and 86% (p = 0.06) for PET/CT.

Conclusion

The results of this study indicate that PET/CT does not significantly improve the detection of recurrence of head and neck cancer. However, a trend towards improved accuracy was observed (p = 0.06).     

Cost reduction in abdominal CT by weight-adjusted dose

Aim

To analyze the influence of contrast dose adjusted by weight vs. fixed contrast dose in the attenuation and cost of abdominal computed tomography (CT).

Materials and methods

A randomised, consecutive, parallel group study was conducted in 151 patients (74 men and 77 women, age range 22–67 years), studied with the same CT helical protocol. A dose at 1.75 ml/kg was administered in 101 patients while 50 patients had a fixed dose of 120 ml of same non-ionic contrast material (320 mg/ml). Mean enhancements were measured at right hepatic lobe, superior abdominal aorta and inferior cava vein. Statistical analysis was weight-stratified (<60, 61–70, 71–80 and >81 kg).

Results

Aortic attenuation was significantly superior (p < 0.05) in the dose adjusted by weight group than in the fixed dose group. Patients who weighed >61 kg in dose-adjusted group, presented higher hepatic attenuation, being statistically significant in those >81 kg (p < 0.01). In dose-adjusted group, there was a savings of €4.1 per patient in patients weighing <80 kg. In patients weighing >80 kg, there was an over cost of €10.7 per patient.

Conclusions

An injection volume of 1.75 ml/kg offers an optimal diagnostic quality with a global savings of €1.34 per patient.     

PET/CT scanning guided intensity-modulated radiotherapy in treatment of recurrent ovarian cancer

Objective

This study was undertaken to evaluate the clinical contribution of positron emission tomography using ¹⁸F-fluorodeoxyglucose and integrated computer tomography (FDG-PET/CT) guided intensity-modulated radiotherapy (IMRT) for treatment of recurrent ovarian cancer.

Materials and methods

Fifty-eight patients with recurrent ovarian cancer from 2003 to 2008 were retrospectively studied. In these patients, 28 received PET/CT guided IMRT (PET/CT–IMRT group), and 30 received CT guided IMRT (CT–IMRT group). Treatment plans, tumor response, toxicities and survival were evaluated.

Results

Changes in GTV delineation were found in 10 (35.7%) patients based on PET–CT information compared with CT data, due to the incorporation of additional lymph node metastases and extension of the metastasis tumor. PET/CT guided IMRT improved tumor response compared to CT–IMRT group (CR: 64.3% vs. 46.7%, P = 0.021; PR: 25.0% vs. 13.3%, P = 0.036). The 3-year overall survival was significantly higher in the PET–CT/IMRT group than control (34.1% vs. 13.2%, P = 0.014).

Conclusions

PET/CT guided IMRT in recurrent ovarian cancer patients improved the delineation of GTV and reduce the likelihood of geographic misses and therefore improve the clinical outcome.     

Predictive role of post-treatment [18F]FDG PET/CT in patients with uterine cervical cancer

Objective

To evaluate the efficacy of post-treatment positron emission tomography (PET)/computed tomography (CT) for identification of tumor recurrence, and to determine whether [¹⁸F]fluorodeoxyglucose (FDG) uptake measured as the maximum standardized uptake value (SUV_max) has predictive role regarding survival in patients with uterine cervical cancer.

Methods

Medical records from 276 women with uterine cervical cancer who had post-treatment [¹⁸F]FDG PET/CT performed were retrospectively reviewed. Results of PET/CT scans were compared with histological or clinical examination.

Results

Ninety-five (34.4%) of the 276 patients had documented recurrence by either surgical biopsy or clinical and imaging follow-up. Median duration from treatment to PET/CT scan was 24 months (range, 6–307). The overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of post-treatment PET/CT were 94.7%, 87.8%, 80.4%, 97%, and 90.2%, respectively. The PET/CT scan modified both the diagnostic or treatment plan in 67 patients (24.3%). Patients were divided into two groups according to cut-off SUV_max established on the basis of ROC analysis (<5.25 vs. ≥5.25), and there was a significant difference in OS between groups (p = 0.001). In addition, the 5-year progression-free survival (PFS) and OS rates of patients with a negative PET/CT scan for recurrence were significantly better than those with a positive PET/CT (98.62% vs. 17.83%, p < 0.0001 for PFS, 99.31% vs. 85.38%, p = 0.0015 for OS).

Conclusion

Post-treatment PET/CT scan is a sensitive and accurate surveillance modality, and provides prognostic information in uterine cervical cancer. Furthermore, it may allow individualization of patient care.     

Intermodality comparison between 3D perfusion CT and 18F-FDG PET/CT imaging for predicting early tumor response in patients with liver metastasis after chemotherapy: Preliminary results of a prospective study

Objectives

To evaluate the feasibility of 3D perfusion CT for predicting early treatment response in patients with liver metastasis from colorectal cancer.

Methods

Seventeen patients with colon cancer and liver metastasis were prospectively enroled to undergo perfusion CT and 18F-FDG-PET/CT before and after one-cycle of chemotherapy. Two radiologists and three nuclear medicine physicians measured various perfusion CT and PET/CT parameters, respectively from the largest hepatic metastasis. Baseline values and reduction rates of the parameters were compared between responders and nonresponders. Spearman correlation test was used to correlate perfusion CT and PET/CT parameters, using RECIST criteria as reference standard.

Results

Nine patients responded to treatment, eight patients were nonresponders. Baseline SUV_mean30 on PET/CT, reduction rates of 30% metabolic volume and 30% lesion glycolysis (LG₃₀) on PET/CT and blood flow (BF) and flow extraction product (FEP) on perfusion CT after chemotherapy were significantly different between responders and nonresponders (P = 0.008–0.046). Reduction rates of BF (correlation coefficient = 0.630) and FEP (correlation coefficient = 0.578) significantly correlated with that of LG₃₀ on PET/CT (P < 0.05).

Conclusion

CT perfusion parameters including BF and FEP may be used as early predictors of tumor response in patients with liver metastasis from colorectal cancer.     

Dual energy spectral CT imaging of insulinoma-Value in preoperative diagnosis compared with conventional multi-detector CT

Objective

The aim of this study was to investigate the value of dual energy spectral CT (DEsCT) imaging in preoperative diagnosis of insulinomas in comparison with conventional multi-detector CT (MDCT).

Materials and methods

Thirty-five patients were included in this study with 14 underwent the conventional dual-phase CT imaging (from March 2009 to January 2010) and 21 underwent the dual-phase DEsCT imaging (from February 2010 to May 2011). CT images were interpreted prospectively by two radiologists in consensus before operation. All the patients had diagnosis confirmed pathologically. The accuracy of preoperative diagnosis of insulinomas between DEsCT imaging and conventional MDCT, and between different kinds of images of DEsCT was compared.

Results

There were 39 confirmed lesions among the 35 patients (23 and 16 tumors in the spectral CT group and MDCT group, respectively). MDCT detected 11 of 16 tumors. DEsCT imaging detected 20 of 23 tumors separately with the monochromatic image or the iodine density image, and 22 of 23 tumors with the combination of the two kinds of images. The sensitivity for the preoperative diagnosis of insulinoma was 95.7% with the combination of monochromatic and iodine density images in DEsCT imaging, statistically higher than that with the conventional MDCT (68.8%) (p = 0.033).

Conclusion

Dual energy spectral CT imaging has higher sensitivity in preoperative diagnosis of insulinomas compared with conventional MDCT. The combination of monochromatic image and iodine density image can improve the diagnostic sensitivity of insulinomas.     

CT differentiation of solid serous cystadenoma vs endocrine tumor of the pancreas

Aim

To differentiate between solid serous cystadenoma (SSCA) and endocrine tumor (ET) of the pancreas using dynamic CT findings.

Materials and methods

Between 2001 and 2008, there were 3 SSCA and 15 ET surgically resected in our institute, for whom preoperative multidetector-row CT were available. Various CT features were retrospectively evaluated by two radiologists in consensus for the differentiation between the two entities. Delay time for early and delayed phase images were 40 and 180 or 240 s, respectively. For qualitative assessment, density of the tumors relative to the surrounding parenchyma was evaluated, along with other characteristic features. In patients for whom digital data were available, CT values of the tumors were measured, and quantitative assessment was also performed. Relative and absolute washout rate (RWR and AWR, respectively) were also calculated.

Results

Mean sizes of the two groups were similar. Tumors were seen as low density area more frequently in SSCA than in ET on unenhanced CT (3/3 vs 1/14), and also on the delayed phase image (2/3 vs 0/14) (p < 0.05). Fibrous capsule was observed more frequently in SSCA (2/3) than in ET (0/14). CT value of the tumor on unenhanced CT was significantly lower, and RWR was higher in SSCA than in ET (p < 0.05, Mann–Whitney's U test). The difference in delayed phase CT density and AWR did not reach statistically significant level.

Conclusion

Unenhanced and enhanced CT findings may be of value in differentiation between SSCA and ET.     

Coronary CT angiography in step-and-shoot technique with 256-slice CT: impact of the field of view on image quality, craniocaudal coverage, and radiation exposure

Purpose

To evaluate the effect of a small field of view (FOV) for step-and-shoot coronary computed tomography angiography (CCTA) on craniocaudal z-coverage per scan step, image quality, and radiation exposure.

Methods

53 patients underwent prospectively ECG-gated CCTA on a 256-slice MDCT scanner using either a FOV > 250 mm (group 1, n = 29) or a FOV ≤ 250 mm (group 2, n = 24). Craniocaudal z-coverage was determined on coronal multiplanar reformations. Image noise, signal-to-noise ratio, contrast-to-noise ratio, and qualitative image parameters were assessed. Radiation dose was estimated from the dose length product and was standardized for a scan range from the main pulmonary artery to the diaphragm in order to make both groups comparable.

Results

Diagnostic image quality was achieved in 91.3% of the coronary artery segments of group 1 and 89.9% in group 2 (p = 0.201). There were no major differences in image noise, SNR, and CNR between both groups. A smaller FOV leads to an increase of craniocaudal coverage of a single CT scan step (r = − 0.879; p ≤ 0.001). There was an increase of 23.8% of the mean z-coverage per scanned subvolume in group 2 (59.9 mm vs. 48.8 mm). Radiation dose was significantly lower in group 2 (229 vs. 285 mGy cm, respectively).

Conclusion

The use of a small transverse FOV for step-and-shoot CCTA at a wide detector CT scanner leads to an increased z-coverage. 2 scan volumes are enough to image the cardiac anatomy. Radiation dose is decreased without negative impact on image quality.     

Radiation dose reduction with the adaptive statistical iterative reconstruction (ASIR) technique for chest CT in children: An intra-individual comparison

Objective

To retrospectively compare radiation dose and image quality of pediatric chest CT using a routine dose protocol reconstructed with filtered back projection (FBP) (the Routine study) and a low-dose protocol with 50% adaptive statistical iterative reconstruction (ASIR) (the ASIR study).

Materials and methods

We retrospectively reviewed chest CT performed in pediatric patients who underwent both the Routine study and the ASIR study on different days between January 2010 and August 2011. Volume CT dose indices (CTDIvol), dose length products (DLP), and effective doses were obtained to estimate radiation dose. The image quality was evaluated objectively as noise measured in the descending aorta and paraspinal muscle, and subjectively by three radiologists for noise, sharpness, artifacts, and diagnostic acceptability using a four-point scale. The paired Student's t-test and the Wilcoxon signed-rank test were used for statistical analysis.

Results

Twenty-six patients (M:F = 13:13, mean age 11.7) were enrolled. The ASIR studies showed 60.3%, 56.2%, and 55.2% reductions in CTDIvol (from 18.73 to 7.43 mGy, P < 0.001), DLP (from 307.42 to 134.51 mGy × cm, P < 0.001), and effective dose (from 4.12 to 1.84 mSv, P < 0.001), respectively, compared with the Routine studies. The objective noise was higher in the paraspinal muscle of the ASIR studies (20.81 vs. 16.67, P = 0.004), but was not different in the aorta (18.23 vs. 18.72, P = 0.726). The subjective image quality demonstrated no difference between the two studies.

Conclusion

A low-dose protocol with 50% ASIR allows radiation dose reduction in pediatric chest CT by more than 55% while maintaining image quality.     

Using low tube voltage (80kVp) quadruple phase liver CT for the detection of hepatocellular carcinoma: two-year experience and comparison with Gd-EOB-DTPA enhanced liver MRI

Purpose

To validate the diagnostic performance of quadruple phase low tube voltage liver CT through the comparison with Gd-EOB-DTPA enhanced liver MRI for the detection of HCC.

Materials and methods

Non-obese patients (38 men, eight women) with 68 HCCs underwent quadruple-phase CT at 16 MDCT (using low tube voltage, 80 kVp; moderately high tube current, 280 mAs) and Gd-EOB-DTPA-enhanced 3 T MRI. Three observers independently and randomly reviewed the CT and MR images on a tumor-by-tumor basis. The diagnostic accuracy of these techniques for detecting HCC was assessed using alternative free-response receiver operating characteristic analysis. Sensitivity and positive predictive values were evaluated. The mean effective doses for the low dose CT were also evaluated.

Results

The areas under the ROC curves were 0.963, 0.959, and 0.941 for low dose CT and 0.981, 0.982, and 0.976 for MRI. Differences in Az of the two techniques for each observer were not statistically significant (P > .05). Differences in sensitivity and positive predictive values between the two techniques for each observer were not also statistically significant: sensitivity (86.8%, 82.4%, 85.3% for CT and 95.6%, 94.1%, 91.2% for MRI) and positive predictive values (92.2%, 90.3%, 89.2% for CT and 92.9%, 92.8%, 92.5% for MRI). Six HCCs (8.8%) in five patients were observed only on hepatobiliary phase of MRI, and all were smaller than 1.5 cm. The mean effective dose for CT was approximately 10.2 mSv.

Conclusions

Quadruple-phase low-dose liver CT (80 kVp, 280 mAs) had relatively good diagnostic performance for detecting HCC in non-obese patients. Because no significant difference was observed between low-dose CT and MRI, the use of low-dose liver CT can be justified based on its reduced radiation effects.     

Low-dose non-enhanced CT versus full-dose contrast-enhanced CT in integrated PET/CT scans for diagnosing ovarian cancer recurrence

Objective

To evaluate low-dose non-enhanced CT (ldCT) and full-dose contrast-enhanced CT (ceCT) in integrated ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT studies for restaging of ovarian cancer.

Materials and methods

One hundred and twenty women who had undergone treatment for ovarian cancer underwent a conventional PET/CT scans with ldCT, and then ceCT. Two observers interpreted and decided in consensus on the PET/ldCT and PET/ceCT images by a 3-point scale (N: negative, E: equivocal, P: positive) per patient and lesion site. Final diagnoses were obtained by histopathological examinations, or clinical follow-up for at least 6 months.

Results

Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET/ceCT was 86.9% (40/46), 95.9% (71/74), and 92.5% (111/120), respectively, whereas those of PET/ldCT were 78.3% (36/46), 95.0% (70/74), and 88.3% (106/120), respectively. All sensitivity, specificity, and accuracy significantly differed between two methods (McNemar test, p < 0.0005, p = 0.023, and p < 0.0001, respectively). The scales of detecting 104 recurrent lesion sites were N:14, E:6, P:84 for PET/ceCT, and N:15, E:17, P:72 for PET/ldCT, respectively. Eleven equivocal and one negative regions by PET/ldCT were correctly interpreted as positive by PET/ceCT.

Conclusion

PET/ceCT is a more accurate imaging modality with higher confidence for assessing ovarian cancer recurrence than PET/ldCT.     

The low attenuation area on dual-energy perfusion CT: correlation with the pulmonary function tests and quantitative CT measurements

Purpose

To retrospectively investigate the distribution of the low attenuation area (LAA) on dual energy perfusion CT (DEpCT) in comparison with the results of pulmonary function tests (PFTs) and quantitative CT measurements.

Materials and methods

Twenty-eight patients (15 male and 13 female; mean age: 62.21 years) underwent DEpCT and PFTs within a 1-month interval. The ranges of the LAA on DEpCT were classified into six groups with attenuation values of 0–3, 0–5, 0–8, 0–10, 0–13 and 0–15 HU and the ratios of LAA in each group were compared with the percentage of forced expiratory volume in the 1st second (%FEV_1.0), FEV_1.0/forced vital capacity (FEV_1.0/FVC) and the relative area of the lung with attenuation coefficients lower than −950 HU (RA₋₉₅₀).

Results

The LAAs on the DEpCT images were significantly correlated with the RA₋₉₅₀, %FEV_1.0 and FEV_1.0/FVC, and the regression analysis showed that the best values of LAA on DEpCT were 0–10 HU with RA₋₉₅₀ (r = 0.63), 0–8 HU with %FEV_1.0 (r = −0.52) and 0–8 HU with FEV_1.0/FVC (r = −0.61) per patient.

Conclusion

The iodine disturbance on DEpCT had a moderate correlation with the results of the PFTs and RA₋₉₅₀, but further examination would be needed for evaluation of iodine distribution.     

CT-guided cutting needle lung biopsy using modified coaxial technique: factors effecting risk of complications

Purpose

We present our 7-year experience with coaxial computed tomography (CT)-guided cutting needle lung biopsy and evaluate the factors affecting risk of complications.

Material and method

Between June 2000 and March 2007, we performed 225 CT-guided coaxial lung biopsies in 213 consecutive patients (161 men, 52 women). Lesion size, lesion depth, lesion location, needle-pleural angle, presence of pleural effusion, patient's position, and complications secondary to biopsy procedure (pneumothorax and bleeding) were noted. Pneumothorax was graded as mild, moderate, and severe. Bleeding complications were graded as mild, moderate, and severe.

Results

Two hundred twenty-five biopsy procedures were performed in 213 patients. The mean diameter of the lung lesion was 41.3 ± 20.1 mm. The mean distance from the peripheral margin of the lesion to the pleura was 17.3 ± 19.2 mm. After 225 procedures, there were 42 mild (18.6%), 13 moderate (5.7%), and 4 severe (1.7%) pneumothoraxes. Small hemoptysis occurred in 27 patients (12%), and mild parenchymal hemorrhage occurred in 2 patients (0.8%). The overall complication rate was 39.1%. Although, a statistically significant correlation was found between female sex, presence of emphysema, lesion depth, and pneumothorax, none of these factors had a predictive value for pneumothorax. Although, statistically significant correlations were found between female sex, lesion size, and bleeding, only lesion size had a predictive value for bleeding.

Conclusion

The most frequent and important complications of this procedure are pneumothorax and bleeding. But any factor is the predictor of pneumothorax and lesion depth is a poor predictor of bleeding complication.     

Routine chest and abdominal high-pitch CT: an alternative low dose protocol with preserved image quality

Objective

To investigate the radiation dose and image quality of the high-pitch dual source computer tomography (DSCT) for routine chest and abdominal scans.

Methods

130 consecutive patients (62 female, 68 male, median age 55 years) were included. All patients underwent 128-slice high-pitch DSCT (chest n = 99; abdomen n = 84) at a pitch of 3.2. Two observers independently rated image quality using a 4-point score (1: excellent to 4: non-diagnostic). Image noise was measured and operational radiation dose quantities were recorded. An additional group of 132 patients (chest, n = 80; abdomen n = 52) scanned with standard-pitch CT matched for age, gender, and body mass index (BMI) served as control group.

Results

Interobserver agreement for image quality rating was good (k = 0.74). Subjective image quality of high-pitch CT was diagnostic in all patients (median score chest; 2, median score abdomen: 2). Image noise of high-pitch CT was comparable to standard-pitch for the chest (p = 0.32) but increased in the abdomen (p < 0.0001). For high-pitch CT radiation dose was 4.4 ± 0.9 mSv (chest) and 6.5 ± 1.2 mSv (abdomen). These values were significantly lower compared to standard-pitch CT (chest: 5.5 ± 1.2 mSv; abdomen: 11.3 ± 3.8 mSv).

Conclusion

Based on the technical background high-pitch dual source CT may serve as an alternative scan mode for low radiation dose routine chest and abdominal CT.     

Unenhanced urinary CT: value of parenchymal attenuation measurements in differentiating acute vs. chronic renal obstruction

Objective

We aimed to search if the renal parenchymal attenuation measurements on unenhanced CT scans could be useful in differentiating acutely obstructed kidneys from chronic cases or unobstructed kidneys.

Material and methods

Unenhanced CT scans of 101 patients were retrospectively reviewed. Thirty-two patients with unilateral acute renal obstruction, 34 patients with unilateral chronic renal obstruction due to various reasons and 35 control subjects were included in the study. The parenchymal densities of both kidneys were measured, from the upper poles, middle portions, and lower poles of each kidney. The mean parenchymal densities of both kidneys were calculated in all three groups of subjects. Secondary signs of renal obstruction such as perinephric stranding, size of ureteral stone, degree of hydronephrosis were also noted for each kidney.

Results

The mean parenchymal attenuation value on the acutely obstructed side was lower than the unobstructed side, 24.21 ± 3.68 and 30.68 ± 4.75 respectively (p < 0.001). The mean parenchymal attenuation value on the acutely obstructed side (24.21 ± 3.68) was lower than both the chronically obstructed side (30.85 ± 4.53), and the control subjects (29.62 ± 3.03 on corresponding side). There was no statistically significant attenuation difference between right and left kidneys in the control group and chronic obstruction group.

Conclusion

Renal parenchymal attenuation measurements and attenuation differences of both kidney of same patient could be useful in differentiating acute unilateral obstruction from chronic cases.     

How accurate are measurements of skin-lesion depths on prebiopsy supine chest computed tomography for transthoracic needle biopsies?

Aim

To evaluate the accuracy of depth measurements on supine chest computed tomography (CT) for transthoracic needle biopsy (TNB).

Materials and methods

We measured skin-lesion depths from the skin surface to nodules on both prebiopsy supine CT scans and CT scans obtained during cone beam CT-guided TNB in the supine (n = 29) or prone (n = 40) position in 69 patients, and analyzed the differences between the two measurements, based on patient position for the biopsy and lesion location.

Results

Skin-lesion depths measured on prebiopsy supine CT scans were significantly larger than those measured on CT scans obtained during TNB in the prone position (p < 0.001; mean difference ± standard deviation (SD), 6.2 ± 5.7 mm; range, 0–18 mm), but the differences showed marginal significance in the supine position (p = 0.051; 3.5 ± 3.9 mm; 0–13 mm). Additionally, the differences were significantly larger for the upper (mean ± SD, 7.8 ± 5.7 mm) and middle (10.1 ± 6.5 mm) lung zones than for the lower lung zones (3.1 ± 3.3 mm) in the prone position (p = 0.011), and were larger for the upper lung zone (4.6 ± 5.0 mm) than for the middle (2.4 ± 2.0 mm) and lower (2.3 ± 2.3 mm) lung zones in the supine position (p = 0.004).

Conclusions

Skin-lesion depths measured on prebiopsy supine chest CT scans were inaccurate for TNB in the prone position, particularly for nodules in the upper and middle lung zones.     

Herpes-Simplex-Virus 1 pneumonia in the immunocompromised host: high-resolution CT patterns in correlation to outcome and follow-up

Objective

To identify the high-resolution CT (HRCT) patterns of Herpes-Simplex-Virus 1 (HSV) pneumonia in immunocompromised patients and correlate findings to outcome and radiographic follow-up until death or complete resolution of findings.

Patients and methods

HRCT data-sets and plain radiographic follow-ups were reviewed in 25 immunocompromised patients with confirmation of new onset HSV-1 pneumonia. Pattern and distribution of abnormalities was assessed by two chest radiologists and findings evaluated regarding outcome and dynamics.

Results

The most frequent CT abnormalities included ground-glass attenuation (n = 18; 72%) in a bilateral, symmetric and random distribution, air-space consolidations (n = 13; 52%) in a bilateral, asymmetric and peribronchial allocation and interlobular septal thickening (n = 6; 24%).When classified by leading HRCT pattern, patients subdivided into distinct groups with either dominant ground-glass attenuation or air-space consolidation. Six patients died after a median 8 days of diagnosis; the median interval until complete radiographic remission of pathology was 20 days. Pre-dominance of air-space consolidations was associated with significant delay of improvement (p = 0.023); however, patient outcome was comparable in both subgroups (p = 0.9).

Conclusion

Diagnosis of HSV pneumonia is challenging and requires familiarity with two distinct HRCT patterns: predominance of ground-glass opacities or air-space consolidations. Whilst the two forms are not linked to patient outcome they demonstrate a variable dynamic at follow-up.     

Iterative reconstruction reduces abdominal CT dose

Objective

In medical imaging, lowering radiation dose from computed tomography scanning, without reducing diagnostic performance is a desired achievement. Iterative image reconstruction may be one tool to achieve dose reduction. This study reports the diagnostic performance using a blending of 50% statistical iterative reconstruction (ASIR) and filtered back projection reconstruction (FBP) compared to standard FBP image reconstruction at different dose levels for liver phantom examinations.

Methods

An anthropomorphic liver phantom was scanned at 250, 185, 155, 140, 120 and 100 mA s, on a 64-slice GE Lightspeed VCT scanner. All scans were reconstructed with ASIR and FBP. Four readers evaluated independently on a 5-point scale 21 images, each containing 32 test sectors. In total 672 areas were assessed. ROC analysis was used to evaluate the differences.

Results

There was a difference in AUC between the 250 mA s FBP images and the 120 and 100 mA s FBP images. ASIR reconstruction gave a significantly higher diagnostic performance compared to standard reconstruction at 100 mA s.

Conclusion

A blending of 50–90% ASIR and FBP may improve image quality of low dose CT examinations of the liver, and thus give a potential for reducing radiation dose.