'Higher the grade-smaller the pedicle': a study of pedicle dimensional variations in 100 cases of high grade lytic spondylolisthesis.

PURPOSE: To measure the pedicle dimensions in high grade lytic spondylolisthesis (HGL) and to classify them, which helps the spine surgeon in proper selection of pedicle screws. METHODS: A study of CT scans in 100 consecutive patients between Jan 2017 and April 2021 diagnosed as single-level HGL on standing radiographs. Pedicle height (PH), Pedicle width (PW), Differential pedicle height (DPH), Screw length (SL) and Transverse pedicle angle (TPA) were measured and analyzed. PH and PW were classified into four grades as-grade A less than 5.0 mm, grade B between 5.0 and 6.0 mm, grade C between 6.0 and 7.0 mm, and grade D above 7.0 mm. RESULTS: 5 males and 95 females with mean age of 49.1 years. PH in 44% lytic vertebra were grade A, B (less than 6 mm) and the rest 56% had grade C, D (greater than 6 mm). PH averaged 6.6 mm in grade 3 HGL, 5.61 mm in grade 4 HGL. Change in PW, SL and TPA was not statistically significant with regards to grade or level of listhesis. A total of 37 cases were noted to have DPH (25 cases had a difference < 2 mm and 12 had a difference > 2 mm). CONCLUSION: 44% of the PH in lytic vertebra was grade A and B (less than 6 mm) that stresses the importance of pre-op CT assessment and planning the appropriate screw dimensions. Change in PH was statistically significant with regards to the grade of listhesis (P-value < 0.01). Differential pedicle height also need to be looked for.

"Single-use peripheral" vs "conventional" reaming in total hip arthroplasty: how to respect native centre of rotation and acetabular offset? A CT study.

PURPOSE: The respect of native hip offset represents a mainstay for satisfying results in total hip arthroplasty (THA). Historically, a great interest has been focused on restoration of femoral offset, while only in recent years, acetabular offset (AO) has been considered. The purpose of the current study was to compare the "single-use peripheral" reaming technique with the "conventional" one for the maintenance of the native COR of the hip and AO in patients undergoing to primary THA. METHODS: Eighty patients affected from primary hip osteoarthritis were prospectively enrolled in the study and were divided in two groups (Group A "single-use peripheral" and Group B "conventional" reaming technique). Pre- and post-operatively, AO, acetabular floor distance (AFd) and acetabular version (AV) were assessed through a CT scan. A comparison between groups for the radiological parameters, surgical time and complications was performed. RESULTS: The demographic data were similar in both groups. The complications rate and the AV did not differ statistically between groups. Group A presented a statistically significant shorter surgical time and lower variation between pre- and post-operative AO and AFd. Statistical significance was defined as p < 0.05. CONCLUSIONS: The "single-use peripheral" reaming technique demonstrated to be more reliable in reproducing the native COR and AO of patients undergoing to primary THA than the "conventional" one. The operative time was significantly reduced, and it may lead to a reduction in the infection risk even though it was not observed in the current study. Further research could be useful to validate such findings and to assess clinical impact and long-term survival of the implant.

Triple-phased mesenteric CT angiography using a test bolus technique for evaluation of the mesenteric vasculature and small intestinal wall contrast enhancement in dogs.

Computed tomography angiography is widely used for the assessment of various mesenteric vascular and bowel diseases in humans. However, there are only few studies that describe CT angiography application to mesenteric vessels in dogs. In this prospective, experimental, exploratory study, the mesenteric vasculature and enhancement pattern of the intestinal wall were evaluated on triple-phase CT angiography, and improvement of the visibility of vasculature was assessed on multiplanar reformation, maximum intensity projection, and volume rendering technique. After test bolus scanning at the level of the cranial mesenteric artery arising from the aorta, mesenteric CT angiography was performed in 10 healthy, male, Beagle dogs. Scan delay was set based on time-to-attenuation curves, drawn by placing the regions of interest over the aorta, intestinal wall, and cranial mesenteric vein. Visualization and enhancement of mesenteric arteries and veins were evaluated with multiplanar reformation, maximum intensity projection, and volume rendering techniques. The degree of intestinal wall enhancement was assessed on the transverse images in precontrast, arterial, intestinal, and venous phases. Pure arterial images were obtained in the arterial phase. Venous phase images allowed good portal vascular mapping. All CT angiography images were of high quality, allowing for excellent visualization of the anatomy of mesenteric vasculature including the small branches, particularly on maximum intensity projection and volume rendering technique. Distinct contrast enhancement of the intestinal wall was observed in both intestinal and venous phases. Findings indicated that this technique is feasible for the evaluation of mesenteric circulation in dogs.

Distal Femoral Valgus Resection Angle in Conventional Total Knee Arthroplasty - a CT Scanogram Study.

Objectives: In conventional total knee arthroplasty (TKA), the distal femur valgus resection angle (DFVA) is decided either by measuring the specific resection angle for each patient on preoperative anteroposterior hip-knee-ankle (HKA) weight-bearing radiograph or using a fixed resection angle of five to seven degrees, when such facilities are not available. This study aims to measure the DVFA in TKA patients using preoperative HKA non-weight-bearing computerized tomography (CT) scanogram scout films and determine its relation with preoperative coronal plane lower-limb deformities. Methods: In this retrospective radiological study, various measurements were performed on bilateral, preoperative hip-knee-ankle CT scanograms of 73 knee osteoarthritis patients who had presented for total knee replacement surgery using a standard protocol. The angle between the femoral anatomical axis and femoral mechanical axis was measured as the femoral mechanical anatomical angle (FMAA), which corresponds to the surgical DFVA. The angle between the femoral and tibial mechanical axes was measured as mechanical femorotibial angle (MFTA). The correlation between FMAA and MFTA was studied. Results: The mean FMAA for the study group was 6.45° (range 3° to 11°, SD 1.17°). The MFTA for the study group ranged from 24° varus to 14° valgus. The alignment was valgus in 14.4% (n=21), varus in 84.2% (n=123), and "0 degrees" in 1.3% (n=2). With valgus coronal alignment taken as positive and varus as negative, the Pearson's correlation coefficient for MFTA with FMAA was r = -0.5183 (p<0.001), indicating that valgus knees tended to have a smaller FMA angle and varus knees tended to have a larger FMA angle. Conclusion: In the non-availability of individualized measurements, in primary TKA, we recommend setting DFVA as five degrees for valgus deformities, six degrees for mild/moderate varus deformities (MFTA <15°) and seven degrees for severe varus deformities (MFTA > 15°).

Automatic detection of new tumors and tumor burden evaluation in longitudinal liver CT scan studies.

PURPOSE: Radiological longitudinal follow-up of liver tumors in CT scans is the standard of care for disease progression assessment and for liver tumor therapy. Finding new tumors in the follow-up scan is essential to determine malignancy, to evaluate the total tumor burden, and to determine treatment efficacy. Since new tumors are typically small, they may be missed by examining radiologists. METHODS: We describe a new method for the automatic detection and segmentation of new tumors in longitudinal liver CT studies and for liver tumors burden quantification. Its inputs are the baseline and follow-up CT scans, the baseline tumors delineation, and a tumor appearance prior model. Its outputs are the new tumors segmentations in the follow-up scan, the tumor burden quantification in both scans, and the tumor burden change. Our method is the first comprehensive method that is explicitly designed to find new liver tumors. It integrates information from the scans, the baseline known tumors delineations, and a tumor appearance prior model in the form of a global convolutional neural network classifier. Unlike other deep learning-based methods, it does not require large tagged training sets. RESULTS: Our experimental results on 246 tumors, of which 97 were new tumors, from 37 longitudinal liver CT studies with radiologist approved ground-truth segmentations, yields a true positive new tumors detection rate of 86 versus 72% with stand-alone detection, and a tumor burden volume overlap error of 16%. CONCLUSIONS: New tumors detection and tumor burden volumetry are important for diagnosis and treatment. Our new method enables a simplified radiologist-friendly workflow that is potentially more accurate and reliable than the existing one by automatically and accurately following known tumors and detecting new tumors in the follow-up scan.

Can low-dose CT with iterative reconstruction reduce both the radiation dose and the amount of iodine contrast medium in a dynamic CT study of the liver?

PURPOSE: To investigate whether low-dose dynamic CT of the liver with iterative reconstruction can reduce both the radiation dose and the amount of contrast medium. MATERIALS AND METHODS: This study was approved by our institutional review board. 113 patients were randomly assigned to one of two groups. Group A/group B (fifty-eight/fifty-five patients) underwent liver dynamic CT at 120/100 kV, with 0/40% adaptive statistical iterative reconstruction (ASIR), with a contrast dose of 600/480 mg I/kg, respectively. Radiation exposure was estimated based on the manufacturer's phantom data. The enhancement value of the hepatic parenchyma, vessels and the tumor-to-liver contrast of hepatocellular carcinomas (HCCs) were compared between two groups. Two readers independently assessed the CT images of the hepatic parenchyma and HCCs. RESULTS: The mean CT dose indices: 6.38/4.04 mGy, the dose-length products: 194.54/124.57 mGy cm, for group A/group B. The mean enhancement value of the hepatic parenchyma and the tumor-to-liver contrast of HCCs with diameters greater than 1cm in the post-contrast all phases did not differ significantly between two groups (P>0.05). The enhancement values of vessels in group B were significantly higher than that in group A in the delayed phases (P<0.05). Two reader's confidence levels for the hepatic parenchyma in the delayed phases and HCCs did not differ significantly between the groups (P>0.05). CONCLUSIONS: Low-dose dynamic CT with ASIR can reduce both the radiation dose and the amount of contrast medium without image quality degradation, compared to conventional dynamic CT without ASIR.

Pulmonary nodule registration in serial CT scans using global rib matching and nodule template matching.

We propose an automatic nodule registration method between baseline and follow-up chest CT scans. Initial alignment using the center of the lung volume corrects the gross translational mismatch, and rigid registration using coronal and sagittal maximum intensity projection images effectively refines the rigid motion of the lungs. Nodule correspondences are established by finding the most similar region in terms of density as well as the geometrical constraint. The proposed nodule registration method increased the nodule hit rate (the ratio of the number of successfully matched nodules to total nodule number) from 26% to 100%.

A two center 320 slice CT study for evaluating coronary arteries in subjects with chronic atrial fibrillation: a comparison of prospective and retrospective ECG-gating acquisition.

PURPOSE: To compare diagnostic-accuracy of prospective and retrospective-ECG-gated acquisition in 320-slice-CT for detecting coronary-artery stenosis in subjects with chronic-atrial-fibrillation (CAF) in a two-center study. MATERIALS AND METHODS: 53 CAF subjects who underwent 320-slice-CT, and invasive-coronary-angiogram (ICA) within 6-months (43 male; 69 ± 9 years; CHADS2 score 2.2 ± 1.3; CHA2DS2-VASc score 3.5 ± 1.6) in the two institutes were analyzed. In Institute-1, prospective-ECG-gated acquisition was routinely performed (N=33). In Institute-2, retrospective-ECG-gated acquisition was routinely performed (N=20). CT and ICA data were transferred to the analysis center and were analyzed by cardiologists blinded to the clinical-data. RESULTS: Prevalence of >50 and >75% on ICA was 79 and 61% in Institute-1, and 30 and 15% in Institute-2, respectively. In a patient-by-patient analysis, Institute-2 had higher negative-predictive-value (NPV) and accuracy of >75% stenosis on CT in predicting >75% stenosis on ICA. In a vessel-by-vessel analysis, there were no significant-differences of sensitivity, specificity, positive-predictive-value (PPV) and NPV of >50% stenosis on CT in predicting >50% stenosis on ICA between both institutes. But sensitivity, specificity, and NPV of >75% stenosis on CT in predicting >75% stenosis on ICA were significantly higher in Institute-2 than in Institute-1. This is mainly because of more severe coronary-artery disease including calcification in Institute-1; there might also have been an influence of differences in scanning and reconstruction methods. CONCLUSIONS: 320-slice-CT shows relatively high diagnostic-accuracy for the detection of significant coronary-artery stenosis compared with ICA even in CAF subjects, in a two-center analysis. Retrospective-ECG-gated acquisition in 320-slice-CT shows significantly higher diagnostic-accuracy than prospective-ECG-gated acquisition for detection of >75% coronary-artery stenosis.