Computed Tomography (CT)

Background: Lung weight characterises severity of pulmonary oedema and predicts response to mechanical ventilation. The aim of this study was to evaluate the accuracy of quantitative analysis of thorax computed tomography (CT) for measuring lung weight in pigs with or without pulmonary oedema.

Preoperative cervical and thoracic spine T2-weighted sagittal MRI showed that the mass was located in the dura mater and extended from C6 to Th6, and the spinal cord had been dorsally shifted (Fig. 2A). Preoperative T2-weighted axial MRI showed a mass of high-intensity signal, which was located in the right ventral space of the spinal cord, and this mass maximally compressed spinal cord at Th2 level (Fig. 2B). The dura mater was deformed into an oval shape from the inner side by the intradural mass. The reported signs of intradural-extra-arachnoid hematoma on MRI included a “black line,” which is a line in the dura mater on T2-weighted axial image, but it could not be observed in the present case (Shimada et al. 1996). Brain computed tomography (CT) showed a high-density area in the subarachnoid space that appeared to be a sub- arachnoid hemorrhage (Fig. 3). Brain MRI showed no rup-

The Dose Datamed methodology explained in the European Guidance No 154 [15] was used. The X-ray examinations were grouped into seven radiological mo- dalities: radiography, conventional fluoroscopy, diagnos- tic interventional radiology, therapeutic interventional radiology, computed tomography, dental radiology, mam- mography, and bone densitometry. Concerning CT, the participants were asked to give the annual number of pro- cedures related to over 50 types, or in case this was not possible, for about 20 broader categories. The participants were also allowed to provide data in their own format.

Small animals, especially rodents, are essential models for preclinical studies, and they play an important role in modeling human physiology and development, and in guiding the study of human diseases and in seeking effective treatment [2]. The ability to directly visualize dynamics with high spatiotemporal resolution in these small-animal models at the whole- body scale provides insights into biological processes at the whole organism level [28]. In addition to high spatiotemporal resolution, the ideal non-invasive small-animal imaging technique should provide deep penetration, and anatomical and functional contrasts. Previously, small-animal whole-body imaging has typically relied on non-optical approaches, including magnetic resonance imaging (MRI), X-ray computed tomography (X- ray CT), positron emission tomography (PET) or single-photon emission computed tomography (SPECT), and ultrasound tomography (UST) [29, 30]. Although these techniques provide deep penetration, they suffer from significant limitations. For example, adapting MRI to achieve microscopic resolution requires a costly high magnetic field and a long data acquisition time, ranging from seconds to minutes, too slow for imaging dynamics [31, 32]. X-ray CT lacks functional contrast [33]. PET/SPECT alone suffers from poor spatial resolution. In addition, X-ray CT and PET/SPECT use ionizing radiation, which may inhibit longitudinal monitoring [34]. UST does not image blood oxygenation or extravascular molecular contrasts [35]. To overcome all of the above limitations using one system, we need to develop new imaging modalities.

Computed Tomography (CT) of Orbital Pseudotumour Computed Tomography (CT) of Orbital Pseudotumour A Zulfiqar, MMed* S Abdul Samad, FRCR* D Alias, MS** A Norizan, DCP*** ital * Department of Radiology,[.]

Abstract: X-ray computed tomography (CT) has recently been experiencing remarkable growth as a result of technological advances and new clinical applications. This paper reviews the essential physics of X-ray CT and its major components. Also reviewed are recent promising applications of CT, ie, CT-guided procedures, CT-based thermometry, photon-counting technology, hybrid PET-CT, use of ultrafast-high pitch scanners, and potential use of dual-energy CT for material differentiations. These promising solutions and a better knowledge of their potentialities should allow CT to be used in a safe and effective manner in several clinical applications.

Purpose: This study compared the accuracy of cone beam computed tomography (CBCT) and medical- grade CT in the context of evaluating the diagnostic value and accuracy of fiducial marker localization for reference marker–based guided surgery systems. Materials and Methods: Cadaver mandibles with attached radiopaque gutta-percha markers, as well as glass balls and composite cylinders of known dimensions, were measured manually with a highly accurate digital caliper. The objects were then scanned using a medical-grade CT scanner (Philips Brilliance 64) and five different CBCT scanners (Sirona Galileos, Morita 3D Accuitomo 80, Vatech PaX-Reve3D, 3M Imtech Iluma, and Planmeca ProMax 3D). The data were then imported into commercially available software, and measurements were made of the scanned markers and objects. CT and CBCT measurements were compared to each other and to the caliper measurements. Results: The difference between the CBCT measurements and the caliper measurements was larger than the difference between the CT measurements and the caliper measurements. Measurements of the cadaver mandible and the geometric reference markers were highly accurate with CT. The average absolute errors of the human mandible measurements were 0.03 mm for CT and 0.23 mm for CBCT. The measurement errors of the geometric objects based on CT ranged between 0.00 and 0.12 mm, compared to an error range between 0.00 and 2.17 mm with the CBCT scanners. Conclusions: CT provided the most accurate images in this study, closely followed by one CBCT of the five tested. Although there were differences in the distance measurements of the hard tissue of the human mandible between CT and CBCT, these differences may not be of clinical significance for most diagnostic purposes. The fiducial marker localization error caused by some CBCT scanners may be a problem for guided surgery systems. I nt J O ral M axIllOfac I Mplants 2013;

F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) are often used as preoperative independent variables to evaluate the invasiveness of lung adenocarcinoma. We investigated the associations between these independent variables and pathologic invasiveness in pulmonary adenocarcinomas. Methods: We selected patients with peripheral lung adenocarcinomas, definitively diagnosed by surgical resection, with diameters of ≤ 30 mm over a 4-year period ending in December 2010. The association between 3 independent variables (tumor size, SUVmax, and C/T ratio) and pathologic prognostic factors was evaluated using logistic analysis. Results: We evaluated a total of 163 primary lung adenocarcinomas in 148 patients (93 males and 55 females; age range: 34 to 84 years). Using multivariate logistic regression analysis, SUVmax and the C/T ratio were significantly associated with tumor invasiveness (odds ratio [OR] = 1.227; p = 0.025 and OR = 1.019; p = 0.008, respectively). Tumor size was not associated with invasiveness (OR = 1.003; p = 0.925). For solid type adenocarcinomas, only SUVmax was significantly associated with invasiveness (OR = 1.558; p = 0.003). For subsolid type adenocarcinomas, only the C/T ratio was significantly associated with invasiveness (OR = 1.030; p = 0.009).

33. Oliveira ML, Tosoni GM, Lindsey DH, Men- doza K, Tetradis S, Mallya SM. Influence of ana- tomical location on CT numbers in cone beam computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013 Apr;115(4):558-64. 34. Loubele M, Jacobs R, Maes F, Denis K, White S, Coudyzer W, et al. Image quality vs. ra- diation dose of four cone beam computed tomog- raphy scanners. Dentomaillofacial Radiol. 2008 Sep;37(6):309-18.

Chest computerized tomography (CT) is the currently available imaging platform to assess lung disease after de- struction has occurred. Utilizing tissue density, CT can identify structural damage such as airway enlargement and airway wall thickening and remodelling that occurs in emphysema. Aiming to develop an imaging approach that provides information on both anatomy and cellular pro- cesses related to disease pathogenesis and evolution would add useful clinical information in the evaluation of the dis- ease course, prognosis assessment, and response to treat- ment. Hybrid imaging systems combining single photon emission computed tomography (SPECT) with CT or positron emission tomography (PET) with CT provide platforms to localize and quantify uptake of radiolabelled probes targeting biological markers important in lung disease.

A 15-year-old patient with osteosarcoma of left distal femur underwent a bone scan with Tc-99m hydroxymethylenediphosphonate (HDP). Whole body bone scan revealed extensive bone and thoracic metastases. Single Photon Emission Computed Tomography-Computed Tomography (SPECT-CT) of the thorax localized the uptake at pleura and lung nodules. In this case study we want to share our experience using SPECT-CT.

It is known that respiratory motion leads to significant imaging artifacts which may lead to incorrect treatment planning volumes, lesion localization, or inference of change in tumor volume over time. Respiratory-correlated com- puted tomography (4DCT) using external respiratory surrogates was first pro- posed as solution for this problem [10] [11] [12] [13] and has rapidly become a standard of care for radiotherapy simulation in the presence of respiratory mo- tion [14] [15]. In the intervening years, cone beam computed tomography (CBCT) technology has proliferated on linear accelerators to provide image guidance for radiotherapy verification, and recently, respiratory-correlated cone beam CT (4DCBCT) has become clinically available [16] [17] [18]. Sonke et al. investigated 4DCBCT versus 3DCBCT and fluoroscopy and found motion arti- facts in 4D dataset were substantially reduced compared to a 3D scan [17]. Sweeney et al. investigated inter-observer variability of target localization for 4DCBCT and 3DCBCT imaging with patient data and found significantly re- duced variability with 4DCBCT [19]. Lee et al. and Iramina et al. further ex- amined the impact of scanning parameters and motion sorting methods related to the accuracy of 4DCBCT images [20] [21].

Thirty-one patients with maxillofacial trauma were studied with plain radiography, coronal and lateral pluridirectional tomography PT, and axial and direct coronal computed tomography CT[r]

Fibrous dysplasia (FD) is a rare benign bone disorder in which the normal bone is replaced by immature fibro- osseous tissue. The actual prevalence of FD is difficult to estimate, but it may affect about 1/30,000 persons with a similar distribution around the world. The disease may involve single bone (monostotic FD, 70%) or multiple bones (polyostotic FD, 30%) with a predilection for the craniofacial bones and ribs. Patients are usually asymp- tomatic and detected incidentally on imaging studies that are performed for other purposes. In rare symptom- atic cases, FD can present as bone pain, deformity, or pathologic fracture [1, 2]. 99m Tc-MDP ( 99m Tc-labeled methylene diphosphonate) whole-body bone scans (WBS) has been widely used for detection of metastasis for various malignant diseases. However, some case re- ports have reported that FD showed significantly in- creased 99m Tc-MDP uptake, which may mimic bone metastasis or skeletal involvement of the patients with known cancer [3–5]. Therefore, active diagnosis and radiological familiarity of FD are thought to be essential for distinguishing bone metastasis and preventing un- necessary examinations or therapy. Single photon emis- sion computed tomography/computed tomography (SPECT/CT) offers the opportunity to obtain diagnostic-

Objectives: Bone quality and quantity assessment is one of the most important steps in implant treatment planning. Different methods such as computed tomography (CT) and recently suggested cone beam computed tomography (CBCT) with lower radiation dose and less time and cost are used for bone density assessment. This in vitro study aimed to compare the tissue density values in Hounsfield units (HUs) in CBCT and CT scans of different tissue phantoms with two different thicknesses, two different image acquisition settings and in three locations in the phantoms.

Sir. Wilhelm Conrad Roentgen first discovered X-Rays on 8th November 1895, which eventually led to a series of radiographic techniques in the field of radiology. X-Rays played a vital role in the diagnosis of various diseases from 1895 onwards. Computed Tomography (CT) was a significant development in the history of imaging since the discovery of x- rays (Ambrose, 1973). Computed tomography (x-ray CT) is a technology that uses computer-processed x-rays to produce tomographic images (virtual 'slices') of specific areas of the scanned object, allowing the user to see what is inside it without cutting it open (Cormack, 1973). CT was developed for clinical use in 1972 and 1973 by Godfrey Hounsfield. The information presented in a CT image is different from that in a conventional radiographic image. The most conspicuous difference is that CT shows cross-sectional views of patient anatomy. Sir Godfrey was awarded a Nobel Prize in 1979 for this major achievement (Willi A Kalender, 2006). CT is thus synonymous with Computerized Transverse Axial Tomography (CTAT), Computer-Assisted Tomography or Computerized Axial Tomography (CAT), Computerized Tomography (CT), Reconstructive Tomography (RT), and Computerized Transaxial Transmission reconstructive

Background: Even though magnetic resonance imaging (MRI) is the gold standard investigation for intracranial pathology, it is not widely available in developing countries and computed tomography (CT) of the brain remains the first-line investigation for patients with suspected intracranial pathology. It is generally accepted that certain intracranial pathology can be missed on non-contrast-enhanced CT (NECT) of the brain if a contrast-enhanced CT (CECT) is not done. We have to consider on the one hand the risk of delayed or missed diagnosis and on the other hand the cost, increased radiation exposure and contrast-induced reactions. Advances in CT technology have also improved the resolution of CT scan images, making it easier to identify pathology on an NECT of the brain. To date, no study comparing NECT to CECT of the brain, utilising 64-slice CT technology, has been published.

In patients with IgG4-RD, whole-body organ involvement manifests as increased FDG uptake in multiple organs on fluorodeoxyglucose (FDG) positron-emission tomography (PET) and FDG-PET/computed tomography (CT) [20–26]. Although histopathological examination remains the gold standard for detecting organ involvement and diagnosing IgG4-RD, it is difficult to obtain biopsy or surgical speci- mens from the arterial wall. Hence, non-invasive evaluation of vascular involvement is clinically important not only for diagnosis but also for the management of IgG4-aortitis. FDG-PET/CT has also been reportedly used to assess other inflammatory vascular diseases, such as Takayasu arteritis and giant cell arteritis [27, 28]. However, to our knowledge, no study has described the use of systemic evaluation using FDG-PET/CT co-registered with contrast-enhanced CT (CECT) for IgG4-aortitis.

Talc pneumoconiosis has been described in workers exposed to talc during extraction of magnesium silicate from mines, grinding, packing, and transportation of the product. Another form of talcosis is caused by the endovenous administration of talc seen in drug abusers. Clinical manifestations of talcosis consist of dry cough FIGURE 3. A 63-year-old female patient with amiodarone lung. High-resolution computed tomography with parenchy- mal (A) and mediastinal (B) windows demonstrate peripheral consolidations with air bronchogram, increase of heart volume, and right pleural effusion. In B, the high-density consolidations are shown.

Mesenteric ischaemia comprises a broad, heterogeneous group of diseases characterised by inadequate blood supply to the small or large bowel. Acute mesenteric ischaemia is a surgical emergency, with significant associated morbidity and mortality. Because the clinical presentation of mesenteric is- chaemia is variable and often nonspecific, a high index of clinical and radiologic suspicion is required for early diagno- sis. The severity of mesenteric ischaemia ranges from tran- sient, localised ischaemia to frank necrosis of the bowel. The most common causes of acute mesenteric ischaemia are em- bolic and thrombotic occlusion of the superior mesenteric artery, whereas chronic mesenteric ischaemia is almost always associated with generalised atherosclerotic disease. Multidetector computed tomography (MDCT) angiography is the preferred imaging test for acute and chronic mesenteric ischaemia. MDCT is useful in making a prompt, more precise diagnosis of mesenteric ischaemia, as well as identifying the