CT scan of the liver

Since its inception, CT scan has had a dominant role in hepatic imaging. Recent advances including helical CT scan and bolus-triggered scan initiation software packages have had a significant impact. Issues regarding volume, rate of administration, and type of intravenous contrast are being distilled. Workstations for three-dimensional data reconstructions are producing images that compete with conventional angiography in certain areas, while angiographically assisted CT scan is being refined in others.     

Helical CT reconstruction with longitudinal filtration

Each of the currently used helical reconstruction algorithms represents one tradeoff selection of the image noise or mA requirement and resultant artifacts versus the width of the section profile. For many applications, the performance tradeoffs different from those existed are desired. In this paper, we present a general framework of incorporating the longitudinal (z) filtration in helical CT reconstruction, which leads to a new class of helical reconstruction algorithms with tunable performance characteristics to suit various applications. The z-filtering algorithm enables us to derive the performance curve of image noise or mA requirement versus the width of the section profile, whereas the existing helical reconstruction algorithms only represent limited discrete samples of the curve. We demonstrate that using a new helical reconstruction algorithm derived from this general framework, a substantial reduction in image noise or mA requirement can be achieved with a slight increase of FWHM of the section profile. Thus for many applications requiring both compact section profile and low image noise or mA requirement, the new algorithm represents a better tradeoff than both the 180 degrees and 360 degrees interpolation algorithms. The new algorithm also offers the following potential clinical benefits: (1) longer x-ray tube life; (2) longer scan duration with less x-ray tube cooling delays--longer volume coverage and/or longer thin-slice scan; (3) less radiation to patient; (4) less image noise; and (5) less helical artifacts. Initial clinical results are also presented.     

Abdominopelvic CT scan findings after surgery for ovarian cancer

AIMS: To evaluate abdomino-pelvic changes in patients who had total abdominal hysterectomy (TAH) and bilateral salpingo-oophorectomy (BSO) for stage I ovarian cancer. METHOD: The postoperative computed tomographic (CT) scans of 23 patients who had undergone TAH and BSO for stage I ovarian tumours between 3 and 14 weeks previously were assessed, providing there had been no treatment with chemotherapy or radiotherapy and that each patient had normal tumour marker (CA125) levels after surgery. After the CT scan patients were followed up and had no clinical or biochemical (CA125) evidence of relapse for a median of 27 months (range 11 to 78 months). The following sites were assessed by two observers: the vaginal vault, round ligaments, bladder, rectum, perirectal fat, pelvic sidewalls, omentum, surgical scar and abdominal wall. Any abnormality was recorded, with re-evaluation on follow-up CT scans in ten patients (between three and 17 months). RESULTS: The following abnormalities were seen: (1) Thickened round ligaments (n=12) with bulbous masses at the surgically transected ends (n=7). This was bilateral in eight patients. (2) Vaginal vault thickening (n=11) either uniform (n=6) or bulbous bilaterally (n=2) or unilaterally (n=3). (3) Subtle omental bed stranding or nodularity (n=11). (4) Peritoneal thickening underlying the scar (n=4). (5) Asymmetrical rectus abdominis muscles (n=3) adjacent to the surgical scar or thickened scar tissue in the anterior abdominal wall (n=4). No significant bladder, rectal, perirectal or nodal abnormalities were found. CONCLUSION: Pseudotumours at the transected ends of the round ligaments, or uniformly swollen round ligaments, may be identified in patients who have had TAH and BSO, as may vaginal vault thickening. Other changes which may be observed in the abdomen and pelvis are peritoneal thickening adjacent to the scar and omental bed stranding.     

Three-dimensional CT scan of hemimandibular hyperplasia: case report

Transient absorption spectra of adenine, adenosine and 2'-deoxyadenosine 5'-monophosphate (dAMP) arising from 248 nm laser flash photolysis using acetone as a photosensitizer have been observed. The intermediates recorded are assigned to the excited triplet states and dehydrogenated radicals of adenine and its nucleoside and nucleotide. The excited triplet states of adenine and its derivatives are produced via triplet-triplet excitation transfer and observed for the first time, while the dehydrogenated radicals stemming from the interaction of triplet acetone with adenine and its derivatives via electron transfer through a five-member-ring electron donor-acceptor intermediate. The site of dehydrogenation is suggested to be the hydrogen atom on C(8) of the adenine moiety. Moreover, three sets of kinetic parameters of the triplet decay have been determined. The rate constants of the unimolecular decay (k0), the triplet quenching by the ground state (ksq) and by the triplet quencher Mn2+ (kq) are 1.1 x 10(5), 7.9 x 10(4), 3.7 x 10(4) s-1, 6.9 x 10(8), 8.3 x 10(8), 3.6 x 10(8) dm3 mol-1 s-1 and 4.2 x 10(8), 3.5 x 10(8), 6.0 x 10(8) dm3 mol-1 s-1 respectively for adenine, adenosine and dAMP.     

Reliability of CT scan cerebral hemispheric asymmetry measurements across multiple CT scans and variability in CT scanning angulation.

To date every published paper on CT scan hemispheric asymmetries has measured the asymmetries on only one scan per subject. This study examines whether CT scan hemispheric asymmetry measurements made on individual subjects change category (left, equal, or right) over multiple CT scan times. The asymmetries were measured at each of three scan times for each of 29 subjects (N = 87 scans) by two independent raters. Occipital length asymmetry categories and occipital width asymmetry categories were consistent across multiple CT scans. Frontal length asymmetry categories were not consistent across multiple CT scan times. Frontal width asymmetry categories appear to be more consistent than frontal length asymmetries but less consistent than occipital length or occipital width asymmetries across multiple CT scan times. The inter-rater reliability was most highly correlated for occipital length and occipital width. The inter-rater reliability for frontal width and frontal length asymmetries was also highly correlated. though not as highly as the occipital length or occipital width asymmetries. This study also examined whether CT scan hemispheric asymmetries changed in relation to the angle at which the CT scan was performed. The angulation of the CT scan did not appear to affect the consistency of the CT scan hemispheric asymmetry categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Value of CT scan and MRI in primary tumors of the ovary

Characterisation of an ovarian mass is of utmost importance in the preoperative evaluation of an ovarian neoplasm. It enables the surgeon to anticipate carcinoma of the ovary before the operation, so that adequate procedures are planned. Although, ultrasonography (US) remains the foremost imaging modality for screening patients with adnexal lesions, computed tomography (CT) recently has proved to be of value in the characterisation and management of tumors of the ovary. Magnetic resonance (MR) imaging has also been shown to have a high degree of diagnostic specificity for certain types of ovarian masses, such as dermoid cysts, and endometriomas. However, the potential of MR imaging to characterize tumors of the ovary has not yet been established. This study assesses the value of MR imaging and CT for the purpose of predicting the malignancy of ovarian lesions, and comparing findings of MR imaging with those of CT.     

Subtle diagnostic markers of orbital floor blow-out fracture on coronal CT scan

The sagittal plane, computerized tomography (CT) scan has been proposed as the most important radiological view in the diagnosis of orbital floor blow-out fractures. This view however is impractical and unnecessary. Direct, coronal plane CT scan with careful attention paid to the shape of the inferior rectus muscle and antral roof will successfully diagnose this traumatic condition, as in our reported case in which no other radiological abnormalities were present.     

Virtual cystoscopy based on helical CT scan datasets: perspectives and limitations

The purpose of the study was to simulate cystoscopy based on three-dimensional helical CT scan datasets in real-time in patients with tumours of the urinary bladder. A helical CT scan with double detector technology was carried out pre-operatively in 11 patients with histologically confirmed carcinoma of the urinary bladder and one patient with chronic cystitis. A non-enhanced scan was first performed, followed by an examination in the early phase of contrast medium enhancement. Further images were acquired after adequate filling of the bladder with contrast medium, approximately 30 min after injection. These data were transferred to a separate graphic computer workstation and reconstructed. The results were then compared with the cystoscopic and histopathological findings. All tumours of the urinary bladder identified at fibreoptic cystoscopy were shown on virtual cystoscopy. The best reconstruction results were obtained from data acquired 30 min after injection of contrast medium. The ureteric orifices were not visualized at virtual cystoscopy. These data lead us to conclude that, at present, virtual cystoscopy has not reached the quality of fibreoptic examination and remains restricted to use in specific cases, for example patients with urethral strictures.     

Head trauma: CT scan interpretation by radiology residents versus staff radiologists

The determination of diagnostic features in recorded heart sounds was investigated with Carpentier-Edwards (CE) bioprosthetic valves. Morphological features, extracted using the Choi-Williams distribution, achieved between 96 and 61% correct classification. The time-scale wavelet-transform feature set achieved 100% correct classification with native valve populations, and 87% with the CE replacements.     

CT scan and metrizamide CT cisternography in arachnoid cysts of the middle cranial fossa: classification and pathophysiological aspects

Thirty-one cases of arachnoid cysts of the middle cranial fossa were investigated by CT scan, 7 of them undergoing additional metrizamide CT cisternography. In this paper we analyze and correlate the different findings from these two examinations and propose a classification of arachnoid cysts of the middle cranial fossa into three basic types. Pathophysiological and surgical implications are discussed.     

High-resolution CT scan in the evaluation of exercise-induced interstitial pulmonary edema in cardiac patients

OBJECTIVE: To evaluate the onset of exercise-induced interstitial pulmonary edema in cardiac patients by high-resolution CT (HRCT). DESIGN: Prospective, normal controlled. PARTICIPANTS: Thirty subjects divided into three groups: group 1--10 outpatients with chronic congestive heart failure (CCHF), New York Heart Association (NYHA) class I; group 2--10 outpatients with CCHF, NYHA class II/III; and group 3 (control)--10 normal subjects. METHOD: HRCT scans were obtained at rest and 4, 8, 12, 16, and 20 min after progressive treadmill exercise test. RESULTS: The following HRCT findings consistent with interstitial edema were significantly different (p<0.05) in group 2 when compared with groups 1 and 3: artery/bronchus ratio > 1 in the upper lobes, peripheral increase in the vascular markings, interlobular septal thickening, and peribronchial "cuffing." These differences were maximal at 12 min after exercise and returned to normal values after 20 min. CONCLUSION: Interstitial pulmonary edema was present immediately after exercise in CCHF patients. It may be important in the genesis of dyspnea of these patients.     

Postoperative follow-up of juvenile nasopharyngeal angiofibromas: assessment by CT scan and MR imaging

The purpose of this study was to assess the radiological findings after surgical removal of juvenile nasopharyngeal angiofibromas (JNA). The postoperative CT and MRI scans of ten patients were reviewed. The cured group included six patients. The non-controlled group included six patients with eight recurrences. Two patients belonged to both groups as they were also followed and cured after surgery for relapse. Four recurrences were asymptomatic and diagnosed by imaging. The imaging patterns were matched to the patients clinical status and endoscopic findings. In the cured group, non-enhanced residual soft tissue masses were seen in all cases. In the non-controlled group, recurrence was always demonstrated on early postoperative CT or MR as a dramatically enhanced mass. The recurrence was located in the lateral or superior aspect of the nasopharynx (n = 3), deep to the fossa of Rosenmuller (n = 4) or out of the nasopharynx (n = 1). In two cases a remaining enhanced mass disappeared spontaneously on iterated examinations. Because of numerous asymptomatic relapses, a radiological workup is recommended four months after surgery, even in patients with normal endoscopy, to rule out posterolateral or extranasopharyngeal recurrences. Spontaneous evolution of residual masses must be appreciated on iterated imaging examinations.     

Spontaneous rupture of the rectum. Contribution of CT scan. Apropos of a case

We report a case of spontaneous rupture of the rectosigmoid junction demonstrated by surgical and histological examination. This rare complication of chronic constipation is difficult to confirm except in the case of the typical clinical presentation with lower abdominal pain after defaecation and evisceration of small intestine loops through the anus. No radiological procedure is usually performed except for plain abdominal radiograph, to demonstrate inconstant (retro)peritoneal emphysema. CT scan could detect free air outside of the rectosigmoid lumen, suggesting parietal rupture and allowing appropriate surgical treatment on the lower digestive tract.     

Spiral CT with ionic and nonionic contrast material: evaluation of patient motion and scan quality

STUDY OBJECTIVES: To determine if subcutaneous administration of influenza vaccine is as immunogenic as the intramuscular route, and to evaluate the frequency of local adverse events associated with both routes in elderly anticoagulated men. DESIGN: Single-blind, prospective study of consecutively enrolled subjects. SETTING: Ambulatory clinic at a university-affiliated Veterans Affairs medical center. PATIENTS: Twenty-six men age 60 years or older, receiving therapeutic dosages of warfarin. INTERVENTIONS: Subjects were randomized to receive either intramuscular or subcutaneous injection of a standard trivalent influenza vaccine. MEASUREMENTS AND MAIN RESULTS: Serum antibody titers to the vaccine's components were measured at baseline, and 6 weeks and 4 months after vaccination. Both routes of administration induced comparable serum antibody titers. There were no differences in adverse events at administration sites between routes of administration. CONCLUSIONS: Elderly individuals are able to mount an immune response to influenza vaccine and produce antibody concentrations deemed protective. The routes of administration are similarly effective at inducing an immune response. The intramuscular route in anticoagulated elderly men does not commonly result in local bleeding complications.     

Three-dimensional PET emission scan registration and transmission scan synthesis

The duration of a positron emission tomography (PET) imaging scan can be reduced if the transmission scan of one patient which is used for emission correction can be synthesized by using the reference transmission scan of another patient. In this paper, we propose a new intersubjects PET emission scan registration method and PET transmission synthesis method by using the boundary information of the body or brain scan of the PET emission scans. The PET emission scans have poor image quality and different intensity statistics so that we preprocess the emission scans to have similar histogram and then apply the point distribution model (PDM) [15] to extract the contours of the emission scan. The extracted boundary contour of every slice is used to reconstruct the three-dimensional (3-D) surface of the reference set and the target set. Our registration is 3-D surface-based which uses the normal flow method [17] to find the correspondence vector field between two 3-D reconstructed surfaces. Since it is difficult to analyze internal organ using the PET emission scan imaging without correction, we assume that the deformation of internal organ is homogeneous. With the corresponding vector field between the two emission scans and the transmission scan of the reference set, we can synthesize the transmission scan of the target set.