Transient interruption of contrast on CT pulmonary angiography: effect of mid-inspiratory vs. end-inspiratory respiration command

PURPOSE

To investigate the effects of mid-inspiratory respiration commands and other factors on transient interruption of contrast (TIC) incidence on CT pulmonary angiography.

METHODS

In this retrospective study, 824 patients (mean age, 66.1 ± 15.3 years; 342 males) who had undergone CT pulmonary angiography between January 2021 and February 2023 were included. Among them, 545 and 279 patients were scanned at end- and mid-inspiratory levels, respectively. By placing a circular region of interest, CT attenuation of the main pulmonary artery (CTMPA) was recorded. Associations between several factors, including patient age, body weight, sex, respiratory command vs. TIC and severe TIC incidence (defined as CTMPA < 200 and 150 HU, respectively), were assessed using logistic regression analyses with stepwise regression selection based on Akaike's information criterion.

RESULTS

Mid-inspiratory respiration command, in addition to patient age and lighter body weight, had negative association with the incidence of TIC. Only patient age, lighter body weight, female sex, and larger cardiothoracic ratio were negatively associated with severe TIC incidence. Mid-inspiratory respiration commands helped reduce TIC incidence among patients aged < 65 years (p = 0.039) and those with body weight ≥ 75 kg (p = 0.005) who were at high TIC risk.

CONCLUSION

Changing the respiratory command from end- to mid-inspiratory levels, as well as patient age and body weight, was significantly associated with TIC incidence.

Hypodense cerebral venous sinus thrombosis on unenhanced CT: Time-dependent change of CT attenuation in intravenous thrombus

Cerebral venous sinus thrombosis (CVST) is an important cause of stroke, which accounts for 0.5%-1% of all strokes. CVST is principally manifested as headaches, papilledema, psychiatric symptoms, impaired consciousness and seizure disorders, with or without neurological defects. We encountered a case of CVST after subacute phase, revealing a hypodense thrombus in the superior sagittal sinus (SSS) on unenhanced CT. Retrospective observation of the serial unenhanced CT images taken at another hospital showed that the SSS thrombus changed from high to low attenuation for 10 days. RBCs dominant CVST at acute phase shows high attenuation on unenhanced CT and is effective for heparin therapy, whereas CVST after subacute phase shows low attenuation on unenhanced CT by the thrombus contents of fibrin, hemosiderin and collagen, and may be ineffective to heparin therapy. Therefore, it is important to accurately identify high attenuation of the CVST at acute phase on unenhanced CT and treat with heparin as early as possible.

Utilizing machine learning for opportunistic screening for low BMD using CT scans of the cervical spine

BACKGROUND

Computed Tomography (CT) scans of the cervical spine are often performed to evaluate patients for trauma and degenerative changes of the cervical spine. We hypothesized that the CT attenuation of the cervical vertebrae can be used to identify patients who should be screened for osteoporosis.

METHODS

Retrospective study of 253 patients (177 training/validation and 76 test) with unenhanced CT scans of the cervical spine and DXA studies within 12 months of each other. Volumetric segmentation of C1-T1, clivus, and first ribs was performed to obtain the CT attenuation of each bone. The correlations of the CT attenuations between the bones and with DXA measurements were evaluated. Univariate receiver operator characteristic (ROC) analyses, and multivariate classifiers (Random Forest (RF), XGBoost, Naïve Bayes (NB), and Support Vector Machines (SVM)) analyzing the CT attenuation of all bones, were utilized to predict patients with osteopenia/osteoporosis and femoral neck bone mineral density (BMD) T-scores <-1.

RESULTS

There were positive correlations between the CT attenuation of each bone, and with the DXA measurements. A CT attenuation threshold of 305.2 Hounsfield Units (HU) at C3 had the highest accuracy =0.763 (AUC=0.814) to detect femoral neck BMD T-scores ≤-1 and a CT attenuation threshold of 323.6 HU at C3 had the highest accuracy=0.774 (AUC=0.843) to detect osteopenia/osteoporosis. The SVM classifier (AUC=0.756) had higher AUC than the RF (AUC=0.692, P=0.224), XGBoost (AUC=0.736; P=0.814), NB (AUC=0.622, P=0.133) and CT threshold of 305.2 HU at C3 (AUC=0.704, P=0.531) classifiers to identify patients with femoral neck BMD T-scores <-1. The SVM classifier (accuracy=0.816) was more accurate than using the CT threshold of 305.2 HU at C3 (accuracy=0.671) (McNemar's χ₁²=7.55, P=0.006).

CONCLUSION

Opportunistic screening for low BMD can be done using cervical spine CT scans. A SVM classifier was more accurate than using the CT threshold of 305.2 HU at C3.

Opportunistic CT screening of osteoporosis on thoracic and lumbar spine: a meta-analysis

BACKGROUND

Osteoporotic fractures are a major contributor to late life morbidity and mortality, and impose a substantial societal cost, yet osteoporosis remains substantially underdiagnosed and undertreated. The purpose of this meta-analysis was to assess the pooled diagnostic sensitivity and specificity of computed tomography (CT) images for diagnosing osteoporosis in patients who meet WHO dual X-ray absorptiometry (DXA) osteoporosis criteria using specific Hounsfield unit (HU) values as a threshold.

METHODS

Systematic literature searches in PubMed, Embase, Web of Science and Google Scholar were performed from the earliest available date through 1 July 2018, restricted to publications in English. Participants in all studies underwent CT scans that included the lumbar and/or thoracic spine for different indications and HU measurements were used to identify osteoporosis. DXA scans served as the reference standard.

RESULTS

Ten eligible studies were identified. The mean area under the hierarchical summary receiver operating characteristic (ROC) curve for diagnosis osteoporosis was 0.84 (95% CI: 0.81, 0.87). The pooled diagnostic sensitivity and specificity of CT images to identify osteoporosis were 0.83 (95% CI: 0.73, 0.90) and 0.74 (95% CI: 0.69, 0.79). The positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio were 3.4 (95% CI: 2.7, 4.5), 0.21 (95% CI: 0.12, 0.36), and 16.4 (95% CI: 7.8, 34.3), respectively. The bias-adjusted sensitivity and specificity of CT were 0.73 and 0.71. Meta-regression demonstrated that country of study, DXA criteria and scanner manufacturer were significant factors associated with the sensitivity of CT in detecting osteoporosis while scanner manufacturer was the only factor associated with specificity of CT.

CONCLUSIONS

This meta-analysis showed reasonable pooled sensitivity and specificity for using threshold values measured on CT scans to identify osteoporosis opportunistically.

Utility of absolute apparent diffusion coefficient and chemical-shift imaging versus CT attenuation for predicting malignancy from percutaneous bone biopsies

INTRODUCTION

Bone lesions are sometimes detected on computed tomography studies, and biopsies are performed to evaluate whether these are malignant. The aim of the study is to evaluate whether chemical-shift imaging (CSI) and diffusion-weighted imaging (DWI) magnetic resonance imaging (MRI) are more informative than the CT attenuation for predicting malignancy.

METHODS

Retrospective analysis of 86 patients who underwent both diagnostic CT, CSI MRI and DWI MRI within 6 weeks prior to bone biopsy at a tertiary care academic institution between 01/01/2010 and 03/01/2020. The CT attenuation, signal intensity on in-phase sequences (SIIP), signal intensity on out-of-phase sequences (SIOP), signal intensity ratio (SIR = SIOP/SIIP) and the apparent diffusion coefficient (ADC) of the lesions over the region of the biopsy tract were measured.

RESULTS

A threshold CT attenuation of 157 Hounsfield Units (HU) had a sensitivity of 47.7%, specificity of 83.3% and area under the curve (AUC) of 0.59. A threshold ADC of 793 × 10-6 mm2 /s had a sensitivity of 75.8%, specificity of 85.7% and AUC of 0.83 to predict whether a bone biopsy would detect malignancy. A threshold SIR of 0.949 had a sensitivity of 77.8%, specificity of 77.8% and AUC of 0.81 to predict whether a bone biopsy would detect malignancy. ADC (P = 0.029) and SIR (P = 0.009) were significantly better than CT attenuation. There was no predictive difference between SIR and ADC (P = 0.742).

CONCLUSIONS

The CT attenuation of a lesion is a poor predictor of malignancy in bone lesions. CSI and DWI are significantly better for predicting malignancy.

CT Attenuation and Cross-sectional-area Index of the Pectoralis Are Associated With Prognosis in Sarcoma Patients

BACKGROUND/AIM

To identify prognostic imaging biomarkers from staging chest computed tomography (CT) in patients with sarcomas.

PATIENTS AND METHODS

CT scans for baseline staging, and surveillance 1-year CT scans in patients newly diagnosed with sarcoma were evaluated. Pectoralis muscle area (PMA), pectoralis muscle index (PMI) and pectoralis CT attenuation density (PMT) were measured. Cox proportional-hazard models were used to determine the association with progression-free survival (PFS) and overall survival (OS).

RESULTS

There were 147 patients (53.1% male) who were followed for a median 1,414 days (range=219-4851 days). Approximately 47.6% (70/147) of patients progressed and 29.9% (44/147) died. Multivariable Cox-proportional hazards models adjusting for gender, tumor grade and chemotherapy treatment showed that a higher baseline PMT and baseline PMI were associated with increased OS.

CONCLUSION

Higher baseline PMI and PMT are associated with increased overall survival in patients with sarcoma.

Pericoronary adipose tissue CT attenuation and its association with serum levels of atherosclerosis-relevant inflammatory mediators, coronary calcification and major adverse cardiac events

BACKGROUND

Increased attenuation of pericoronary adipose tissue (PCAT) around the right coronary artery (RCA) derived from coronary CTA might detect coronary inflammation. We investigated a potential association between RCA PCAT attenuation and serum levels of atherosclerosis-relevant cytokines and MACE (coronary revascularization, myocardial infarction and/or cardiac death).

METHODS

Blood samples of 293 clinically stable individuals (59.0 ​± ​9.8 years, 69% males) were analyzed for atherosclerosis-relevant cytokines including interleukin (IL)-2, IL- 4, IL-6, IL-7, IL-8, IL-10, IL-13, IL-15, IL-17, TNF-a, IP-10, CRP, MCP-1, MIP-1a, Eotaxin and GM-CSF. Subjects also underwent coronary calcium scoring (CCS) followed by CTA. PCAT CT attenuation was measured around the RCA using semi-automated software. Increased RCA PCAT attenuation was defined as PCAT attenuation above the 75th percentile (>-73.5 HU). To assess MACE, 232 individuals were followed for a mean duration of 9.6 ​± ​2.1 years.

RESULTS

In patients with increased RCA PCAT attenuation the serum levels of MCP-1 were increased (p ​< ​0.01), whereas levels of anti-inflammatory mediators IL-4 and -13 were significantly reduced (each p ​< ​0.05). Adipocytokine MCP-1 (r ​= ​0.23, p ​< ​0.01) and pro-inflammatory mediator IL-7 (r ​= ​0.12, p ​= ​0.04) showed a mild positive correlation with RCA PCAT attenuation, whereas anti-inflammatory mediators Il-4, -10 and -13 correlated inversely (each r < -0.12, each p ​< ​0.05). 40/232 patients experienced MACE during follow-up. In multivariable Cox regression analysis increased RCA PCAT attenuation was shown to be an independent predictor of MACE (HR 2.01, p ​= ​0.044).

CONCLUSIONS

Increased RCA PCAT CT attenuation shows a weak association with serum levels of selected atherosclerosis-relevant inflammatory biomarkers. Increased RCA PCAT attenuation is an independent predictor of MACE and may potentially guide future prevention strategies in stable patients.

Minute changes of cerebral parenchymal non-contrast computed tomography attenuation reflect cerebral volume alterations of blood

AIMS

Non-infarcted acute cerebral ischaemic areas appear hypo-attenuated on non-contrast narrow-window computed tomography images. We aimed to determine the mechanism underlying minute computed tomography hypo-attenuation and visualise these attenuation changes on non-contrast computed tomography images.

METHODS

The cerebral parenchyma was defined by pixels with attenuation of 20-50 Hounsfield units. We calculated the mean cerebral parenchymal attenuation in non-contrast computed tomography images. We analysed the correlation of complete blood counts with corresponding mean cerebral parenchymal attenuation values using linear regression analysis. Moreover, we developed an image processing method that involved pixel colorisation based on the noise-reduced attenuation value for minute cerebral parenchymal attenuation visualisation.

RESULTS

Haemoglobin, haematocrit and red blood cell counts positively correlated with mean cerebral parenchymal attenuation values. The cerebral haematocrit is correlated with the blood haematocrit; therefore, cerebral parenchymal attenuation correlated linearly with cerebral haemoglobin concentration. Haemoglobin contents in a pixel partially determine the X-ray absorption dose and attenuation value. Pixel haemoglobin contents are determined by the cerebral volume of blood in a pixel. Image processed computed tomography images reflected cerebral volume of blood and showed the same alterations with regional cerebral blood volume maps of perfusion computed tomography.

CONCLUSIONS

Cerebral parenchymal attenuation correlated with cerebral haemoglobin concentration and cerebral volume of blood. Infarcted cerebral parenchyma shows about 5 Hounsfield units gray matter attenuation decrease. Attenuation decrease by less than 5 Hounsfield units means decreased cerebral volume of blood, indicating a reversible functional change. One cannot recognise minute hypo-attenuation (<5 Hounsfield units) in routine computed tomography images. However, it can be visualised through an image processing method on non-contrast computed tomography images. It may detect pre-infarction cerebral volume of blood and regional cerebral blood volume alterations.

Atypical Enostoses-Series of Ten Cases and Literature Review

Bone islands (BI; enostoses) may be solitary or occur in the setting of osteopoikilosis (multiple bone islands) and are sometimes associated with Gardner’s Syndrome (osteopoikilosis and colonic polyposis). Characteristic features of bone islands are (1) absence of pain or local tenderness, (2) typical radio dense central appearance with peripheral radiating spicules (rose thorn), (3) Mean CT (computerized tomography) attenuation values above 885 Hounsfield units (HU) (4) absence of uptake on bone scan and (5) radiographic stability over time. However, when enostoses display atypical features of pain, unusual radiographic appearance, aberrant HU, increased radiotracer uptake, and/or enlargement, they can be difficult to differentiate from more sinister bony lesions such as osteoblastic metastasis, low grade central osteosarcoma, osteoid osteoma and osteoblastoma. In this retrospective case series, the demographic, clinical, radiographic, treatment and outcome for ten patients with eleven atypical bone islands (ABI) are presented, some showing associated pain (5), some with atypical radiographic appearance (3), some with increased activity on BS (4), some with documented enlargement over time (7), one with abnormal CT attenuation value, some in the setting of osteopoikilosis (2), one in the setting of Gardner’s Syndrome and one osteoid osteoma simulating a bone island. This series represents the spectrum of presentations of ABI. Comprehensive review of the literature reveals that the previous largest series of ABI showing enlargement as the atypical feature was in younger patients with jaw BI. Hence, this represents one of the largest series reported of ABI of all types in adults.

Relationship between changes in pericoronary adipose tissue attenuation and coronary plaque burden quantified from coronary computed tomography angiography

AIMS

Increased attenuation of pericoronary adipose tissue (PCAT) around the proximal right coronary artery (RCA) from coronary computed tomography angiography (CTA) has been shown to be associated with coronary inflammation and improved prediction of cardiac death over plaque features. Our aim was to investigate whether PCAT CT attenuation is related to progression of coronary plaque burden.

METHODS AND RESULTS

We analysed CTA studies of 111 stable patients (age 59.2 ± 9.8 years, 77% male) who underwent sequential CTA (3.4 ± 1.6 years between scans) with identical acquisition protocols. Total plaque (TP), calcified plaque (CP), non-calcified plaque (NCP), and low-density non-calcified plaque (LD-NCP) volumes and corresponding burden (plaque volume × 100%/vessel volume) were quantified using semi-automated software. PCAT CT attenuation (HU) was measured around the proximal RCA, the most standardized method for PCAT analysis. Patients with an increase in NCP burden (n = 51) showed an increase in PCAT attenuation, whereas patients with a decrease in NCP burden (n = 60) showed a decrease {4.4 [95% confidence interval (CI) 2.6-6.2] vs. -2.78 (95% CI -4.6 to -1.0) HU, P < 0.0001}. Changes in PCAT attenuation correlated with changes in the burden of NCP (r = 0.55, P < 0.001) and LD-NCP (r = 0.24, P = 0.01); but not CP burden (P = 0.3). Increased baseline PCAT attenuation ≥-75 HU was independently associated with increase in NCP (odds ratio 3.07, 95% CI 1.4-7.0; P < 0.008) and TP burden on follow-up CTA.

CONCLUSION

PCAT attenuation measured from routine CTA is related to the progression of NCP and TP burden. This imaging biomarker may help to identify patients at increased risk of high-risk plaque progression and allow monitoring of beneficial changes from medical therapy.

Visceral Adipose Tissue Radiodensity Is Linked to Prognosis in Hepatocellular Carcinoma Patients Treated with Selective Internal Radiation Therapy

Hepatocellular carcinoma (HCC) constitutes the fourth leading cause of cancer-related mortality. Various factors, such as tumor size, tumor multiplicity, and liver function, have been linked to the prognosis of HCC. The aim of this study was to explore the prognostic significance of muscle, subcutaneous and visceral adipose tissue (VAT) mass, and radiodensity, in a cohort of 101 HCC patients treated with selective internal radiation therapy (SIRT). Muscle and adipose tissue cross sectional area (cm²/m²) and radiodensity, reported as the Hounsfield Unit (HU), were determined using pre-SIRT computed tomography images. Cox proportional hazard models and exact logistic regression were conducted to assess associations between body composition and adverse outcomes. Majority of the patients were male (88%) with a mean VAT radiodensity of −85 ± 9 HU. VAT radiodensity was independently associated with mortality (HR 1.05; 95% CI: 1.01–1.08; p = 0.01), after adjusting for cirrhosis etiology, Barcelona Clinic Liver Cancer stage, previous HCC treatment, and portal hypertension markers. Patients with a high VAT radiodensity of ≥–85 HU had a two times higher risk of mortality (HR 2.01, 95% CI 1.14–3.54, p = 0.02), compared to their counterpart. Clinical features of portal hypertension were more prevalent in patients with high VAT radiodensity. High VAT radiodensity was associated with severe adverse events after adjusting for confounding factors. High VAT radiodensity is independently associated with both increased mortality and severe adverse events in patients treated with SIRT. VAT radiodensity measurement might serve as an objective approach to identify patients who will experience the most benefit from SIRT.

Improved detection of metastatic lymph nodes in oesophageal squamous cell carcinoma by combined interpretation of fluorine-18-fluorodeoxyglucose positron-emission tomography/computed tomography

Background

We sought to evaluate the diagnostic performance of fluorine-18-fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸F-FDG PET/CT) in the detection of metastatic lymph nodes by combined interpretation of PET/CT images in patients with oesophageal squamous cell carcinoma.

Methods

Two hundred three patients with oesophageal squamous cell carcinoma underwent ¹⁸F-FDG PET/CT before oesophagectomy and lymph node dissection. Maximum standardized uptake value (SUV_max), mean Hounsfield unit (HU), short axis diameter (size), and visual CT attenuation (high, iso-, low) were evaluated on noncontrast CT and PET images following PET/CT scan. In this combined interpretation protocol, the high attenuated lymph nodes were considered benign, even if the SUV_max value was high. The diagnostic accuracy of each method was compared using the postoperative histologic result as a reference standard.

Results

A total of 1099 nodal stations were dissected and 949 nodal stations were proven to demonstrate metastasis. SUV_max and size of the malignant lymph nodes were higher than those of the benign nodes, and visual CT attenuation was significantly different among the two groups (P < 0.001). Using cutoff values of 2.6 for SUV_max and 10.2 mm for size, the combined interpretation of an SUV_max of more than 2.6 with iso- or low CT attenuation [area under the curve (AUC): 0.846, 95% confidence interval (CI): 0.824–0.867] showed significantly better diagnostic performance for detecting malignant lymph nodes than SUV_max only (AUC: 0.791, 95% CI: 0.766–0.815) and size (AUC: 0.693, 95% CI: 0.665–0.720) methods (P < 0.001) in a receiver operating characteristic curve analysis.

Conclusions

The diagnostic accuracy of PET/CT for nodal metastasis in oesophageal squamous cell carcinoma was improved by the combined interpretation of ¹⁸F-FDG uptake and visual CT attenuation pattern.

Characterizing Bone Mineral Density Using Lumbar Spine Computed Tomography Attenuation in Patients With Distal Radius Fractures

Introduction:

This study examines how many patients with distal radius fracture (DRF) eligible for bone health evaluation could potentially be screened using bone mineral density (BMD) estimation by L1 vertebra computed tomography (CT) attenuation obtained for other purposes.

Materials and Methods:

For all adult patients with DRF who presented over a 5-year period, we recorded the age, sex, dual-energy X-ray absorptiometry (DXA) results up to 3 years prior to injury or 1 year post-injury, and L1 CT attenuation on any CT including L1 that had been performed within 6 months of their fracture.¹ We compared the availability of L1 CT attenuation measurement to the rate of DXA scan use. We calculated the percentage of patients with osteoporosis and compared attenuation results to DXA results in those patients where both tests were available.

Results:

Of 1853 patients with DRF, an L1 CT had been obtained in 195 patients. Of the 685 patients who met criteria for osteoporosis screening, 253 (37%) patients had undergone only DXA screening, 68 (10%) patients had an L1 CT only, and 18 (2%) patients had both tests. Of the 86 patients who met criteria for osteoporosis screening and had an adequate CT, 67 (78%) demonstrated L1 attenuation <135 HU, and 79 (92%) had CT attenuation <160 HU.

Discussion:

Our study found that 10% of patients with a distal radius fracture who met the criteria for osteoporosis screening had a CT scan that could be used to estimate bone density and that the majority of those patients met criteria for osteoporosis based on CT attenuation.

Conclusions:

Utilization of opportunistic BMD screening with L1 CT attenuation offers the potential to increase osteoporosis screening from 40% to 50% of eligible patients and make the diagnosis of osteoporosis in an additional 8% of patients with DRF at no additional cost.

Concordance between fine-needle aspiration and core biopsies for osseous lesions by lesion imaging appearance and CT attenuation. Radiol Med. 2018;123:254-259. [PMID: 29249078 DOI: 10.1007/s11547-017-0841-8]

OBJECTIVES

To compare the concordance between fine-needle aspiration and core biopsies for osseous lesions by lesion imaging appearance and CT attenuation.

MATERIALS AND METHODS

Retrospective review of 215 FNAs of osseous lesions performed in conjunction with core biopsy at our institution over a 6-year period (2011-2016). FNAs were interpreted independently of core biopsies. We assessed if FNA in conjunction with core biopsy increased diagnostic accuracy compared to core biopsy alone. We also calculated the concordance between FNA and core biopsy by lesion appearance, lesion CT attenuation, lesion histology, lesion location and FNA needle gauge size.

RESULTS

Core biopsy alone provided the diagnosis in 207/215 cases (96.3%), however, the FNA provided the diagnosis in the remaining 8/215 cases (3.7%) where the core biopsy was non-diagnostic. There were 154 (71.6%) lytic lesions, 21 (9.8%) blastic lesions, 25 (11.6%) mixed lytic and blastic lesions and 15 (7.0%) lesions that were neither lytic nor blastic. The concordance between FNA and core biopsy for lytic osseous lesions (136/154 cases, 88.3%) was statistically significantly higher than that for blastic osseous lesions (13/21 cases, 61.9%) [P = 4.2 × 10^-3; 95% CI (0.02, 0.50)]. The concordance between FNA and core biopsy was higher for low-attenuation- (110/126) than high-attenuation (58/77) lesions (P = 0.028). The concordance between FNA and core biopsy was also higher for metastases (102/119 cases, 85.7%) than non-metastases (78/96, 81.3%) [P = 0.487; 95% CI (- 0.15, 0.065)]. There was no difference in the rate of concordance between FNA and core biopsy by lesion location or FNA needle gauge size (P > 0.05).

CONCLUSION

FNA with core biopsy increases diagnostic rate compared to core biopsy alone or FNA alone. The concordance between FNA and core biopsy is higher for lytic lesions than for blastic lesions; and higher for low-attenuation lesions than for high-attenuation lesions.

Can lymphovascular invasion be predicted by preoperative multiphasic dynamic CT in patients with advanced gastric cancer?

OBJECTIVES

To determine whether multiphasic dynamic CT can preoperatively predict lymphovascular invasion (LVI) in advanced gastric cancer (AGC).

METHODS

278 patients with AGC who underwent preoperative multiphasic dynamic CT were retrospectively recruited. Tumour CT attenuation difference between non-contrast and arterial (Δ_AP), portal (Δ_PP) and delayed phase (Δ_DP), tumour-spleen attenuation difference in the portal phase (Δ_T-S), tumour contrast enhancement ratios (CERs), tumour-to-spleen ratio (TSR) and tumour volumes were obtained. All CT-derived parameters and clinicopathological variables associated with LVI were analysed by univariate analysis, followed by multivariate and receiver operator characteristics (ROC) analysis. Associations between CT predictors for LVI and histopathological characteristics were evaluated by the chi-square test.

RESULTS

Δ_PP (OR, 1.056; 95% CI: 1.032-1.080) and Δ_T-S (OR, 1.043; 95% CI: 1.020-1.066) are independent predictors for LVI in AGC. Δ_PP, Δ_T-S and their combination correctly predicted LVI in 74.8% (AUC, 0.775; sensitivity, 88.6%; specificity, 54.1%), 68.7% (AUC, 0.747; sensitivity, 68.3%; specificity, 69.4%) and 71.7% (AUC, 0.800; sensitivity, 67.6%; specificity, 77.8%), respectively. There were significant associations between CT predictors for LVI with tumour histological differentiation and Lauren classification.

CONCLUSION

Multiphasic dynamic CT provides a non-invasive method to predict LVI in AGC through quantitative enhancement measurement.

KEY POINTS

• Lymphovascular invasion rarely can be evaluated preoperatively in advanced gastric cancer (AGC). • Δ _PP and Δ _T-S were independent predictors for LVI in patients with AGC. • Δ _PP and Δ _T-S showed acceptable predictive performance for LVI. • Combination of Δ _PP and Δ _T-S improved predictive performance for LVI. • Multiphasic dynamic CT may be a useful adjunct for detecting LVI preoperatively.

Differential diagnosis of pelvic cystic lesions caused by hemorrhage from inflammatory abscess using CT attenuation in women with acute abdomen

To determine the efficacy of computed tomography (CT) attenuation of cystic lesions measured on an image browsing system to distinguish abscess from hematoma in women with acute abdomen. The medical records of female patients of reproductive age with acute abdomen who were treated over a 7-year period in a single center and who had undergone laparotomy or laparoscopic surgery and preoperative pelvic CT scanning were retrospectively analyzed to identify those with hematoma or abscess cyst formation. Nineteen patients with tubo-ovarian abscess (abscess group) and six patients with hematoma (hematoma group) formation in the pelvis were included in the analysis. The preoperative CT images of the tubo-ovarian cyst were retrospectively investigated on the basis of cyst attenuation. CT attenuation of the cyst measured by both two gynecologists could be used to clearly distinguish inflammatory disease with abscess formation from bleeding disease with hematoma. CT attenuation on a picture archiving and communication system can distinguish hematoma from abscess in women with acute abdomen. This may significantly contribute to making differential diagnosis without interpretation by a medical radiologist.

Opportunistic computed tomography screening shows a high incidence of osteoporosis in ankylosing spondylitis patients with acute vertebral fractures

Advanced ankylosing spondylitis is associated with reductions in bone mineral density (BMD), contributing to pain and predisposing to fractures. Quantifying this reduction is complicated because overgrowth of bone and loss of trabecular bone occur concurrently. Traditional methods such as dual-energy X-ray absorptiometry struggle to generate accurate estimates of BMD in these patients. The aim of this study was to evaluate the utility of computed tomography (CT) attenuation in generating estimates of BMD in patients with severe AS who had sustained vertebral fractures. Patients with severe AS and bridging syndesmophytes who presented, with acute fractures of the spine, were reviewed to assess whether they had a CT scan in the 6 mo before or after injury that included an image of the L1 vertebra; if it did, the scans were selected for analysis. A total of 17 patients were evaluated. Using a CT attenuation threshold of 135 HU balanced for sensitivity and specificity, 14 of 17 (82%) patients were osteoporotic. Using a CT attenuation threshold for higher sensitivity (160 HU), 15 of 17 (88%) patients were osteoporotic. Even using the L1 CT attenuation threshold of 110 HU for higher specificity, 14 of 17 (82%) patients were osteoporotic. CT attenuation demonstrates that a high proportion of AS patients who sustain fractures have osteoporosis. This overcomes some of the difficulties that have been encountered with the use of dual-energy X-ray absorptiometry in this group of patients. This simple and accessible method saves on time, cost, and exposure to radiation and can help in the planning of a patient's management.

The use of computed tomography attenuation to evaluate osteoporosis following acute fractures of the thoracic and lumbar vertebra

BACKGROUND

Relatively few patients have dual-energy x-ray absorptiometry to quantify the magnitude of bone loss as they age. Recent work correlates mean computed tomography (CT) attenuation in the level I (L1) vertebra with bone mineral density (BMD), making it possible to objectively evaluate the magnitude of bone loss in osteoporosis by this method. The aims of this study were to evaluate the utility of using CT scans in patients with acute thoracic and lumbar spine fractures to diagnose osteoporosis and using CT attenuation to evaluate the association between age and BMD.

METHODS

We performed a retrospective study of patients with acute fractures of the thoracic or lumbar spine who had also undergone an abdominal (or L1) CT scan and compared mean CT attenuation in L1 against threshold values. We also compared differences in CT attenuation between younger (<65 years) and older (≥65 years) and older patients.

RESULTS

A total of 124 patients were evaluated (74 thoracic and 50 lumbar fractures). Overall, there was a strong correlation between age and bone density as measured by CT attenuation (r = -.76). Among those with thoracic fractures (<65 years), mean CT attenuation was 196.51 HU. Forty-one patients were ≥65 years and had mean CT attenuation of 105.90 HU (P < .001). In patients with lumbar fractures, 27 patients were <65 years and had a mean CT attenuation of 192.26 HU and 23 patients were ≥65 years and had mean CT attenuation of 114.31 HU (P < .001). At the threshold of 110 HU, set for specificity, the magnitude of difference between the age-stratified cohorts was greater in the thoracic spine (P < .0001 vs P = .003).

DISCUSSION

Using opportunistic CT, we demonstrate the relative frequency of osteoporosis in patients with acute fractures of the thoracic and lumbar spine and confirm that the association increases with age. The CT attenuation may provide a cheap and convenient method to help confirm a clinical diagnosis of osteoporosis in patients with fractures.