Precontrast Computed Tomography Scans Research Articles

Prognostic Value of Artificial Intelligence-Driven, Computed Tomography-Based, Volumetric Assessment of the Volume and Density of Muscle in Patients With Colon Cancer.

The prognostic value of the volume and density of skeletal muscles in the abdominal waist of patients with colon cancer remains unclear. This study aimed to investigate the association between the automated computed tomography (CT)-based volume and density of the muscle in the abdominal waist and survival outcomes in patients with colon cancer. We retrospectively evaluated 474 patients with colon cancer who underwent surgery with curative intent between January 2010 and October 2017. Volumetric skeletal muscle index and muscular density were measured at the abdominal waist using artificial intelligence (AI)-based volumetric segmentation of body composition on preoperative pre-contrast CT images. Patients were grouped based on their skeletal muscle index (sarcopenia vs. not) and muscular density (myosteatosis vs. not) values and combinations (normal, sarcopenia alone, myosteatosis alone, and combined sarcopenia and myosteatosis). Postsurgical disease-free survival (DFS) and overall survival (OS) were analyzed using univariable and multivariable analyses, including multivariable Cox proportional hazard regression. Univariable analysis showed that DFS and OS were significantly worse for the sarcopenia group than for the non-sarcopenia group (P = 0.044 and P = 0.003, respectively, by log-rank test) and for the myosteatosis group than for the non-myosteatosis group (P < 0.001 by log-rank test for all). In the multivariable analysis, the myosteatotic muscle type was associated with worse DFS (adjusted hazard ratio [aHR], 1.89 [95% confidence interval, 1.25-2.86]; P = 0.003) and OS (aHR, 1.90 [95% confidence interval, 1.84-3.04]; P = 0.008) than the normal muscle type. The combined muscle type showed worse OS than the normal muscle type (aHR, 1.95 [95% confidence interval, 1.08-3.54]; P = 0.027). Preoperative volumetric sarcopenia and myosteatosis, automatically assessed from pre-contrast CT scans using AI-based software, adversely affect survival outcomes in patients with colon cancer.

Single-energy computed tomography-based pulmonary perfusion imaging: Proof-of-principle in a canine model.

Purpose:Radiotherapy (RT) that selectively avoids irradiating highly functional lung regions may reduce pulmonary toxicity, which is substantial in lung cancer RT. Single-energy computed tomography (CT) pulmonary perfusion imaging has several advantages (e.g., higher resolution) over other modalities and has great potential for widespread clinical implementation, particularly in RT. The purpose of this study was to establish proof-of-principle for single-energy CT perfusion imaging.Methods:Single-energy CT perfusion imaging is based on the following: (1) acquisition of end-inspiratory breath-hold CT scans before and after intravenous injection of iodinated contrast agents, (2) deformable image registration (DIR) for spatial mapping of those two CT image data sets, and (3) subtraction of the precontrast image data set from the postcontrast image data set, yielding a map of regional Hounsfield unit (HU) enhancement, a surrogate for regional perfusion. In a protocol approved by the institutional animal care and use committee, the authors acquired CT scans in the prone position for a total of 14 anesthetized canines (seven canines with normal lungs and seven canines with diseased lungs). The elastix algorithm was used for DIR. The accuracy of DIR was evaluated based on the target registration error (TRE) of 50 anatomic pulmonary landmarks per subject for 10 randomly selected subjects as well as on singularities (i.e., regions where the displacement vector field is not bijective). Prior to perfusion computation, HUs of the precontrast end-inspiratory image were corrected for variation in the lung inflation level between the precontrast and postcontrast end-inspiratory CT scans, using a model built from two additional precontrast CT scans at end-expiration and midinspiration. The authors also assessed spatial heterogeneity and gravitationally directed gradients of regional perfusion for normal lung subjects and diseased lung subjects using a two-sample two-tailed t-test.Results:The mean TRE (and standard deviation) was 0.6 ± 0.7 mm (smaller than the voxel dimension) for DIR between pre contrast and postcontrast end-inspiratory CT image data sets. No singularities were observed in the displacement vector fields. The mean HU enhancement (and standard deviation) was 37.3 ± 10.5 HU for normal lung subjects and 30.7 ± 13.5 HU for diseased lung subjects. Spatial heterogeneity of regional perfusion was found to be higher for diseased lung subjects than for normal lung subjects, i.e., a mean coefficient of variation of 2.06 vs 1.59 (p = 0.07). The average gravitationally directed gradient was strong and significant (R2 = 0.99, p < 0.01) for normal lung dogs, whereas it was moderate and nonsignificant (R2 = 0.61, p = 0.12) for diseased lung dogs.Conclusions:This canine study demonstrated the accuracy of DIR with subvoxel TREs on average, higher spatial heterogeneity of regional perfusion for diseased lung subjects than for normal lung subjects, and a strong gravitationally directed gradient for normal lung subjects, providing proof-of-principle for single-energy CT pulmonary perfusion imaging. Further studies such as comparison with other perfusion imaging modalities will be necessary to validate the physiological significance.

Imaging characteristics of sinonasal organized hematoma.

Sinonasal organized hematoma is a rare benign disease that may be mistaken for malignancy. To define the imaging characteristics of sinonasal organized hematoma. We retrospectively reviewed computed tomography (CT) images of eight patients (4 male patients, 4 female patients; mean age, 40 years; range, 9-83 years) with pathologically proven sinonasal organized hematomas; magnetic resonance imaging (MRI) was performed in one patient among them. The following lesions characteristics were analyzed: size, shape, location, expansile nature, density, signal intensity, internal structure, enhancement pattern, and surrounding bony wall change. The lesion sizes were in the range of 2-5.2 cm (mean, 3.55 cm), and the shapes were lobular, lumpy, or nodular. They were located in the nasal cavity (n = 1), maxillary sinuses (n = 2), or both nasal cavities and maxillary sinuses (n = 5). Expansile lesions with locally aggressive margins were observed in two cases. All lesions were hyperdense on precontrast CT scans; the smaller lesions showed even hyperdensity, whereas the larger lesions showed uneven density. The signal intensity was mixed on MRI, consisting of hemorrhage, fibrosis, and neovascularization. Papillary or frond-like enhancement was noted after contrast injection. All cases showed smooth erosion of the medial walls of the maxillary sinuses, and the epicenters were the secondary maxillary ostia. Two lesions showed erosion of the lateral walls of the maxillary sinuses and were expansile in nature. Non-hemorrhagic polyps accompanied the organized hematomas in three cases. Although sinonasal organized hematoma can be mistaken for a malignant tumor, the following characteristic imaging findings facilitate the diagnosis of an organized hematoma: erosion of the bony sinus walls, markedly heterogeneous signal intensity, and papillary or frond-like enhancement.

Nasal polyps with metaplastic ossification: CT and MR imaging findings

Metaplastic ossification is a rare event in nasal polyps. The purpose of this study was to review the computed tomography (CT) and magnetic resonance (MR) imaging findings of nasal polyps with metaplastic ossification. CT (n=5) and MR (n=3) images of five patients (four men and one woman; mean age, 59 years) with surgically proven nasal polyp with metaplastic ossification were retrospectively reviewed. The location and morphologic characteristics of metaplastic ossification were documented as well. All lesions were seen as lobulated (n=3), ovoid (n=1), or dumbbell-shaped (n=1) benign-looking masses with a mean size of 3.7 cm (range, 2.4-6.5 cm), located unilaterally in the posterior nasal cavity and nasopharynx (n=2), posterior nasoethmoidal tract (n=2), and maxillary sinus and nasal cavity (n=1). Compared with the brain stem, the soft tissue components of all lesions demonstrated isoattenuation on precontrast CT scans, slight hypointensity on T1-weighted MR images, and hyperintensity on T2-weighted MR images. On contrast-enhanced MR images, heterogeneous enhancement with marked peripheral enhancement was seen in two and homogeneous moderate enhancement in one. All lesions contained centrally located radiodense materials on CT scans, the shape of which was multiple clustered in three, single nodular in one, and single large lobulated in one. Although rare, metaplastic ossification can occur within nasal polyps. The possibility of its diagnosis may be raised when one sees a benign-looking sinonasal mass with centrally located radiodense materials on CT scans. MR imaging may be useful when mycetoma or inverted papilloma cannot be ruled out on CT scans.

Differentiation between cholesteatoma and inflammatory process of the middle ear, based on contrast-enhanced computed tomography imaging

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Differentiation between cholesteatoma and inflammatory process of the middle ear, based on contrast-enhanced computed tomography imaging

To assess the usefulness of delayed post-contrast computed tomography (CT) examination for the detection of residual or recurrent cholesteatoma after canal wall up tympanoplasty. This prospective, non-randomized study, set within an academic medical centre, included 17 consecutive patients who had undergone canal wall up tympanoplasty for cholesteatoma, with possible recurrence. Pre-contrast CT scans and delayed post-contrast images were compared with second look surgical findings. A residual or recurrent cholesteatoma was found in eight of the 17 patients at revision surgery and was correctly diagnosed on post-contrast CT images in six patients (75 per cent). In the two misdiagnosed cases, cholesteatoma pearls smaller than 2.5 mm were not seen on post-contrast CT. The sensitivity of the imaging test was 75 per cent, the specificity was 60.1 per cent, the positive predictive value was 88.1 per cent and the negative predictive value was 81.8 per cent. Computed tomography with delayed post-contrast images is a sensitive imaging modality for the detection of residual cholesteatoma. If proven reliable, this method of non-invasive imaging could spare the patient unnecessary revision surgery.

Multiphasic helical computed tomography predicts subsequent development of severe brain edema in acute ischemic stroke.

To evaluate the use of multiphasic helical computed tomography (CT) in predicting subsequent development of severe brain edema in patients with acute middle cerebral artery (MCA) stroke. Case-control study. Tertiary referral hospital. We studied 31 patients with acute MCA stroke who had a baseline National Institutes of Health Stroke Scale score of 15 or higher within 6 hours of symptom onset. Sequential 4-phasic enhanced helical CT scans were performed after taking precontrast CT scans. The severity of perfusion deficit was graded as "severe" or "moderate" depending on collateral blood flow. Patients were classified as having severe brain edema if they showed signs of uncal herniation or deterioration with mass effect leading to hemicraniectomy. Severe brain edema developed in 10 patients (32%). Severe perfusion deficit greater than 50% of the presumed MCA territory on multiphasic helical CT was more often found in patients with severe brain edema than in those without (8 of 10 vs 4 of 21, P =.002). In contrast, parenchymal hypodensity greater than 50% on precontrast CT was observed only in 5 patients with severe brain edema (5 of 10 vs 4 of 21, P =.10). Additional involvement of the anterior or posterior cerebral artery territory was found on multiphasic CT (6 of 10 vs 0 of 21, P <.001) and on precontrast CT (4 of 10 vs 0 of 21, P =.007) only in patients with severe brain edema. Multiphasic helical CT is more useful than precontrast CT for predicting subsequent severe brain edema in acute MCA stroke based on the findings of severe perfusion deficit greater than 50% of the MCA territory and additional involvement of the anterior or posterior cerebral artery territory.

Liver: Single Breath-hold Dynamic Subtraction CT with Multi–Detector Row Helical Technology—Feasibility Study

Fifty-two patients with known or suspected hypervascular malignancy were examined to determine the technical feasibility of performing single-breath-hold dynamic subtraction computed tomography (CT) of the liver with multi-detector row helical CT. The precontrast and hepatic arterial CT scans, which were acquired during the same breath hold, were subtracted. The mean liver-to-muscle contrast ratio on the precontrast, hepatic arterial, and subtracted images was 1.3, 1.4, and 2.3, respectively. In 13 patients with lesions, the subtracted images showed a 2.5-fold increase in mean lesion contrast compared with the hepatic arterial CT scans.

Value of CT and sonography in the conservative management of acute splenoportal and superior mesenteric venous thrombosis.

Acute splenoportal and superior mesenteric venous thrombosis were diagnosed on sonography and computed tomography (CT) in six patients. Sonography demonstrated the presence of echoic material filling the involved vessels in all patients. Precontrast CT scans demonstrated an increased, intra luminal density of the clots in four patients with splenoportal thrombosis. However, in two cases of superior mesenteric venous thrombosis, no hyperdensity was observed within the lumens. Nevertheless, the clots were always visualized as low-density regions in the vessel lumens after bolus injection. Intravenous anticoagulant therapy was started immediately after the diagnosis. All patients were evaluated twice a week with sonography and/or CT until recanalization occurred. The patency of the previously involved vessels was assessed from 6 days to 4 weeks after the acute episode (average time of recanalization: 17 days) without development of collateral pathways. It is concluded that, in the absence of clinical signs of a life-threatening process, a conservative management of acute splanchnic thrombosis can be successfully achieved by (1) early diagnosis, (2) efficacious intravenous anticoagulant therapy, (3) careful imaging follow-up of these patients by sonography and/or CT during the acute phase and, finally, (4) by an extensive search for a hypercoagulable state.

"Pseudo-Delta Sign" on Computed Tomography in an Extremely Acute Stage of Superior Sagittal Sinus Thrombosis—A Case Report

A case of superior sagittal sinus (SSS) thrombosis with a "pseudo-delta sign" on computed tomography (CT) is reported. The so-called "empty delta sign," which usually appears following contrast enhancement, is reliable in the CT diagnosis of SSS thrombosis but may not appear, it is said, in the extremely acute stage. In this patient, however, the "empty delta sign" appeared with precontrast CT scans and disappeared with postcontrast CT scans, "pseudo-delta sign," in the extremely acute stage of SSS thrombosis. On the precontrast CT, blood surrounding the sagittal sinus outlined it; when contrast was given, it became dense with blood.

Peripheral cholangiocarcinoma and clonorchiasis: CT findings.

Sixteen patients with peripheral cholangiocarcinoma of the liver were examined with computed tomography (CT). None of the 16 patients presented with jaundice or had documented cirrhosis. On scans obtained both before and after the injection of contrast material, the tumors were depicted as low-attenuation masses in all cases, with wide variations in homogeneity. The tumor margin was irregular in 12 cases, and there was minimal contrast enhancement of the tumor in 14 cases. In 11 (69%) patients, CT demonstrated masses of markedly low attenuation, which corresponded to areas of diffuse microcystic change seen at histologic examination of resected specimens. In ten (63%) patients, the results of stool or intradermal tests for Clonorchis sinensis were positive. In all ten cases of clonorchiasis, mild, diffuse dilatation of the intrahepatic bile ducts was seen in addition to the low-attenuation masses, but there was no dilatation of the extrahepatic biliary tree. In five of the ten patients with clonorchiasis, stippled or aggregated, powderlike areas of high attenuation were seen on precontrast CT scans; at pathologic examination, those areas were found to be mucin. Extrahepatic metastases were demonstrated in ten (63%) patients. Peripheral cholangiocarcinoma should be the primary diagnostic consideration when these characteristic CT findings are detected in a noncirrhotic patient.

Postcontrast computed tomography in subarachnoid hemorrhage from ruptured aneurysms.

Computed tomography (CT) scans of 49 patients with subarachnoid hemorrhage (SAH) secondary to ruptured aneurysms were reviewed. Subarachnoid blood was detected in 95% when CT was performed within 5 days after the bleeding. Prediction of the site of the ruptured aneurysm from distribution of the cisternal blood varied from 92% for the anterior cerebral artery aneurysms to 70% for the middle cerebral and 47% for the internal carotid artery aneurysms. Following plain CT scans, postcontrast studies were performed in 27 patients. Aneurysms were directly visualized in 8 cases and subarachnoid enhancement was noted in 21. In 3 cases, subarachnoid enhancement made possible a correct diagnosis of SAH in the absence of evidence of cisternal blood on precontrast CT scans.

Diagnosis of Cranial Asymmetries in Cerebral Arteriovenous Malformations

Nine of 29 patients with cerebral arteriovenous malformations exhibited abnormal cranial asymmetries on computed tomography (CT). Two of these patients showed no other abnormalities on their precontrast CT scans. Assessment of cranial asymmetry is recommended in all patients suspected of having an arteriovenous malformation.