Classical Computed Tomography Research Articles

Caecal epiploic appendagitis: an unlikely occurrence

To determine whether epiploic appendagitis occurs in the caecum. From 2000-2006, 58 cases with classic computed tomography (CT) features of acute epiploic appendagitis (focal round or oval fat density immediately adjacent to the colon with surrounding oedema and stranding, with or without a central area of high attenuation) were identified from a radiology information system and available for review on the picture archiving and communication system (PACS). Cases were assigned to one of six colonic segments: rectum, sigmoid, descending colon, transverse colon, ascending colon, and caecum. The Blyth-Still-Casella procedure was used to derive an exact upper bound on the likelihood of epiploic appendagitis occurring within the caecum. Twenty-eight cases occurred in the sigmoid colon, 16 in the descending colon, four in the transverse colon, and 10 in the ascending colon. No cases of acute epiploic appendagitis were identified in the caecum. Four cases of prospectively dictated caecal epiploic appendagitis were identified from the database. Retrospective review of these cases showed two cases to be epiploic appendagitis of the ascending colon. The third case demonstrated peritoneal thickening without evidence of an inflamed epiploic appendage. The fourth case was caecal diverticulitis. Based on these findings there is 95% confidence that no more than 4.6% of patients with epiploic appendagitis will show this condition within the caecum. In the authors' experience, epiploic appendagitis does not occur in the caecum. Therefore, it is an unlikely cause for an inflammatory process in this region and other conditions should be considered.

Data consistency based translational motion artifact reduction in fan-beam CT

A basic assumption in the classic computed tomography (CT) theory is that an object remains stationary in an entire scan. In biomedical CT/micro-CT, this assumption is often violated. To produce high-resolution images, such as for our recently proposed clinical micro-CT (CMCT) prototype, it is desirable to develop a precise motion estimation and image reconstruction scheme. In this paper, we first extend the Helgason-Ludwig consistency condition (HLCC) from parallel-beam to fan-beam geometry when an object is subject to a translation. Then, we propose a novel method to estimate the motion parameters only from sinograms based on the HLCC. To reconstruct the moving object, we formulate two generalized fan-beam reconstruction methods, which are in filtered backprojection and backprojection filtering formats, respectively. Furthermore, we present numerical simulation results to show that our approach is accurate and robust.

Primary epiploic appendagitis: an underappreciated diagnosis

To determine whether epiploic appendagitis occurs in the caecum.From 2000–2006, 58 cases with classic computed tomography (CT) features of acute epiploic appendagitis (focal round or oval fat density immediately adjacent to the colon with surrounding oedema and stranding, with or without a central area of high attenuation) were identified from a radiology information system and available for review on the picture archiving and communication system (PACS). Cases were assigned to one of six colonic segments: rectum, sigmoid, descending colon, transverse colon, ascending colon, and caecum. The Blyth–Still–Casella procedure was used to derive an exact upper bound on the likelihood of epiploic appendagitis occurring within the caecum.Twenty-eight cases occurred in the sigmoid colon, 16 in the descending colon, four in the transverse colon, and 10 in the ascending colon. No cases of acute epiploic appendagitis were identified in the caecum. Four cases of prospectively dictated caecal epiploic appendagitis were identified from the database. Retrospective review of these cases showed two cases to be epiploic appendagitis of the ascending colon. The third case demonstrated peritoneal thickening without evidence of an inflamed epiploic appendage. The fourth case was caecal diverticulitis. Based on these findings there is 95% confidence that no more than 4.6% of patients with epiploic appendagitis will show this condition within the caecum.In the authors' experience, epiploic appendagitis does not occur in the caecum. Therefore, it is an unlikely cause for an inflammatory process in this region and other conditions should be considered.

Thunderclap Headache: Presentation of Intracranial Sinus Thrombosis?

Intracranial sinus thrombosis (ICST) and subarachnoid haemorrhage (SAH) are common presentations to neuroscience departments, which may indicate potentially life-threatening neurological conditions, however the two disorders require completely different treatment. Non-thrombotic SAH is most frequently the result of ruptured berry aneurysm and often presents with a sudden onset of severe headache. ICST may uncommonly present with thunderclap headache, that is, sudden onset severe headache, thereby mimicking SAH. The classic computed tomography (CT) appearances of SAH and ICST are different and not usually a source of diagnostic mistakes. However, errors can occur and in this paper, we present three cases of ICST that were misdiagnosed as SAH on the clinical presentation and on the initial CT brain examinations.

Computed tomographic findings in patients with invasive fungal sinusitis.

To determine the radiographic findings of computed tomographic (CT) imaging most suggestive of invasive fungal sinusitis (IFS) in an immunocompromised patient population. A retrospective review of patients with a diagnosis of IFS reached with CT and confirmed by histopathologic evaluation. An academic tertiary care hospital. Twenty-three immunocompromised patients with confirmed IFS and preoperative CT imaging. Controls were 10 patients with acute myelocytic leukemia and CT evidence of sinusitis but no history of IFS. The CT scans were reviewed to identify factors predictive of invasive fungal disease. Parameters evaluated were nasal cavity and sinus soft tissue thickening, the presence of air-fluid levels, bone erosion, extrasinus extension, and unilateral or bilateral nasal cavity and sinus involvement. The CT findings included severe soft tissue edema of the nasal cavity mucosa (turbinates, lateral nasal wall and floor, and septum) in 21 of the 23 patients, sinus mucoperiosteal thickening in 21, bone erosion in 8, orbital invasion in 6, facial soft tissue swelling in 5, and retroantral fat pad thickening in 2. Two patients had air-fluid levels. No patients had intracranial involvement. Unilateral involvement was found in 21 patients, and bilateral involvement in 2. Review of the control group revealed only mild soft tissue edema of the nasal cavity in 2 (P<.001), unilateral involvement in 2 (P<.001), and evidence of bone erosion or extrasinus soft tissue involvement in none. Most patients do not have classic CT findings of bone erosion or extrasinus extension in the early course of IFS. We found that severe unilateral thickening of the nasal cavity mucosa was the most consistent finding on CT suggestive of underlying IFS, occurring much more frequently in immunocompromised patients with IFS than without IFS. Even though severe nasal cavity soft tissue thickening is much more common in IFS, this is a nonspecific finding that can be seen, to a lesser degree, in all forms of rhinosinusitis. Therefore, the clinician cannot rely solely on CT imaging and must maintain a high index of suspicion when evaluating immunocompromised patients to establish a prompt diagnosis. Early nasal endoscopy with biopsy and initiation of appropriate therapy are necessary to improve prognosis.

Cystic focal liver lesions in the adult: differential CT and MR imaging features.

Cystic lesions of the liver in the adult can be classified as developmental, neoplastic, inflammatory, or miscellaneous. Although in some cases it is difficult to distinguish these entities with imaging criteria alone, certain cystic focal liver lesions have classic computed tomographic (CT) and magnetic resonance (MR) imaging features, which are important for the radiologist to understand and recognize. Lesions with such features include simple (bile duct) cyst, autosomal dominant polycystic liver disease, biliary hamartoma, Caroli disease, undifferentiated (embryonal) sarcoma, biliary cystadenoma and cystadenocarcinoma, cystic subtypes of primary liver neoplasms, cystic metastases, pyogenic and amebic abscesses, intrahepatic hydatid cyst, extrapancreatic pseudocyst, and intrahepatic hematoma and biloma. Specific CT and MR imaging findings that are important to recognize are the size of the lesion; the presence and thickness of a wall; the presence of septa, calcifications, or internal nodules; the enhancement pattern; the MR cholangiographic appearance; and the signal intensity spectrum. In addition, access to critical clinical information remains extremely important. The most important clinical parameters defined include age and gender, clinical history, and symptoms. An understanding of the classic CT and MR imaging appearances of cystic focal liver lesions will allow more definitive diagnosis and shorten the diagnostic work-up.

Neurofibromatosis Type 1: A Diagnostic Mimicker at CT

Neurofibromatosis type 1 (NF1) is the most common of the phakomatoses and has a variety of localized or, more frequently, systemic manifestations throughout the thorax, abdomen, pelvis, and extremities. Classic computed tomographic (CT) findings in NF1 with thoracic involvement include small, well-defined subcutaneous neurofibromas, focal thoracic scoliosis, posterior vertebral scalloping, enlarged neural foramina, and characteristic rib abnormalities due to bone dysplasia or erosion from adjacent neurofibromas. However, more atypical manifestations are occasionally seen, and magnetic resonance (MR) imaging can be useful in equivocal cases. NF1 with abdominopelvic involvement tends to arise in the retroperitoneal, mesenteric, and paraspinal regions; it may be quite extensive and therefore difficult to distinguish from adenopathy at CT. The multiplanar capabilities of MR imaging, particularly with T2 weighting, make this modality helpful in evaluating affected patients and making the diagnosis. The classic peripheral manifestations of NF1 include limb hemihypertrophy, pseudarthrosis, peripheral nerve neurofibromas, and subcutaneous common and plexiform neurofibromas. In some cases of NF1, imaging findings are inconclusive, and biopsy and subsequent pathologic analysis are required. Familiarity with the various manifestations of NF1 in different anatomic locations is important in making the diagnosis and optimizing postdiagnostic treatment.

Lymphangioleiomyomatosis: abdominopelvic CT and US findings.

To describe the abdominal computed tomographic (CT) and ultrasonographic (US) findings in patients with thoracic lymphangioleiomyomatosis (LAM) and to relate the prevalence of the findings to the severity of pulmonary disease. Eighty patients with LAM underwent chest and abdominopelvic CT and abdominopelvic US. The images were reviewed prospectively by one radiologist, and the abdominal findings were recorded and correlated with the severity of pulmonary disease at thin-section CT. Sixty-one (76%) of 80 patients had positive abdominal findings. The most common abdominal findings included renal angiomyolipoma (AML) in 43 patients (54%), enlarged abdominal lymph nodes in 31 (39%), and lymphangiomyoma in 13 (16%). Less common findings included ascites in eight (10%), dilatation of the thoracic duct in seven (9%), and hepatic AML in three (4%). A significant correlation (P =.02) was observed between enlarged abdominal lymph nodes and increased severity of lung disease. There are characteristic abdominal findings in patients with LAM that, in conjunction with the classic thin-section CT finding of pulmonary cysts, are useful in establishing this diagnosis.

Whole-Body Positron Emission Tomography Using18F-Fluorodeoxyglucose for Posttreatment Evaluation in Hodgkin’s Disease and Non-Hodgkin’s Lymphoma Has Higher Diagnostic and Prognostic Value Than Classical Computed Tomography Scan Imaging

A residual mass after treatment of lymphoma is a clinical challenge, because it may represent vital tumor as well as tissue fibrosis. Metabolic imaging by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) offers the advantage of functional tissue characterization that is largely independent of morphologic criteria. We compared18F-FDG PET to computed tomography (CT) in the posttreatment evaluation of 54 patients with Hodgkin’s disease (HD) or intermediate/high-grade non-Hodgkin’s lymphoma (NHL). Residual masses on CT were observed in 13 of 19 patients with HD and 11 of 35 patients with NHL. Five of 24 patients with residual masses on CT versus 1 of 30 patients without residual masses presented a positive18F-FDG PET study. Relapse occurred in all 6 patients (100%) with a positive 18F-FDG PET, 5 of 19 patients (26%) with residual masses on CT but negative 18F-FDG PET, and 3 of 29 patients (10%) with negative CT scan and18F-FDG PET studies (P ≤ .0001). We observed a higher relapse and death rate in patients with residual masses at CT compared with patients without residual masses at CT (progression-free survival at 1 year: 62 ± 10 v88 ± 7%, P = .0045; overall survival at 1 year: 77 ± 5 v 95 ± 5%, P = .0038). A positive18F-FDG PET study was even more consistently associated with poorer survival: compared with patients with a negative18F-FDG PET study, the 1-year progression-free survival was 0% versus 86% ± 5% (P &lt; .0001) and the 1-year overall survival was 50% ± 20% versus 92% ± 4% (P &lt; .0001). The detection of vital tumor by 18F-FDG PET after the end of treatment has a higher predictive value for relapse than classical CT scan imaging (positive predictive value: 100% v42%). This could help identify patients requiring intensification immediately after completion of chemotherapy. However,18F-FDG PET mainly predicts for early progression but cannot exclude the presence of minimal residual disease, possibly leading to a later relapse.

Whole-Body Positron Emission Tomography Using18F-Fluorodeoxyglucose for Posttreatment Evaluation in Hodgkin's Disease and Non-Hodgkin's Lymphoma Has Higher Diagnostic and Prognostic Value Than Classical Computed Tomography Scan Imaging

AbstractA residual mass after treatment of lymphoma is a clinical challenge, because it may represent vital tumor as well as tissue fibrosis. Metabolic imaging by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) offers the advantage of functional tissue characterization that is largely independent of morphologic criteria. We compared18F-FDG PET to computed tomography (CT) in the posttreatment evaluation of 54 patients with Hodgkin's disease (HD) or intermediate/high-grade non-Hodgkin's lymphoma (NHL). Residual masses on CT were observed in 13 of 19 patients with HD and 11 of 35 patients with NHL. Five of 24 patients with residual masses on CT versus 1 of 30 patients without residual masses presented a positive18F-FDG PET study. Relapse occurred in all 6 patients (100%) with a positive 18F-FDG PET, 5 of 19 patients (26%) with residual masses on CT but negative 18F-FDG PET, and 3 of 29 patients (10%) with negative CT scan and18F-FDG PET studies (P ≤ .0001). We observed a higher relapse and death rate in patients with residual masses at CT compared with patients without residual masses at CT (progression-free survival at 1 year: 62 ± 10 v88 ± 7%, P = .0045; overall survival at 1 year: 77 ± 5 v 95 ± 5%, P = .0038). A positive18F-FDG PET study was even more consistently associated with poorer survival: compared with patients with a negative18F-FDG PET study, the 1-year progression-free survival was 0% versus 86% ± 5% (P < .0001) and the 1-year overall survival was 50% ± 20% versus 92% ± 4% (P < .0001). The detection of vital tumor by 18F-FDG PET after the end of treatment has a higher predictive value for relapse than classical CT scan imaging (positive predictive value: 100% v42%). This could help identify patients requiring intensification immediately after completion of chemotherapy. However,18F-FDG PET mainly predicts for early progression but cannot exclude the presence of minimal residual disease, possibly leading to a later relapse.

Value of 3D CT imaging in fractured os calcis

The authors report their experience with 3D computed tomography (CT) in 23 patients with fractured os calcis (several types of fractures) in comparison to classical 2D CT. The diagnostic accuracy was not found to be improved by the three-dimensional representation. 3D Or is affected by reconstruction artifacts and strongly depends on the choice of threshold. However the 3D visualization is appreciated by the surgeons.