Mesenteric vascular anatomy at CT: normal and abnormal appearances

The appearance of the mesenteric vessels on computed tomographic scans was evaluated in 187 patients to determine the variations in the anatomic relationships between the mesenteric vessels in normal patients, in patients with malrotation, and in patients with abdominal masses. In 166 patients (88.8%), a portion of the cranial segment of the superior mesenteric vein (SMV) was anterior and to the right of the superior mesenteric artery (SMA), although other normal configurations also occurred. A portion of the cranial segment of the SMV was directly anterior to the SMA in 15 patients (8.0%) and directly to the right of the SMA in 16 patients (8.6%). Of eight patients with complete inversion of the SMA and SMV, one had normal midgut rotation, two had malrotation, and six had neoplasms that displaced the vessels (one of these six also had malrotation). Of eight patients with inversion of only a part of the mesenteric vessels, none had malrotation. Although mesenteric inversion should stimulate a careful evaluation for malrotation, it is not pathognomonic of this condition.     

The secondary pulmonary lobule: normal and abnormal CT appearances

The secondary pulmonary lobule is a unit of lung supplied by three to five terminal bronchioles and contained by fibrous septa. High-resolution CT is able to show features of the secondary lobule, including interlobular septa, terminal bronchioles, and pulmonary arteries within a bronchiolovascular bundle. Because interstitial diseases have been shown to affect different components of the secondary lobule, high-resolution CT was used to compare the appearance of the normal secondary lobule with the abnormal secondary lobule in three patients with interstitial diseases primarily affecting lymphatic channels: lymphangitic carcinomatosis, sarcoidosis, and lymphangioleiomyomatosis. In lymphangitic carcinomatosis, the bronchiolovascular bundles and interlobular septa were thicker than those seen in a normal subject. In sarcoidosis, the interlobular septa and bronchiolovascular bundles were also thicker than normal. However, fibrosis caused distortion of the normal polygonal shape of the secondary lobule, not seen in either the normal subject or the patient with lymphangitic carcinomatosis. Lymphangioleiomyomatosis was characterized by multiple cysts within secondary lobules, often obliterating the normal polygonal appearance.     

CT appearances of the normal and abnormal thymus in childhood

Computed tomography in 25 children with diseases of the thymus was evaluated to determine which features are the most useful in diagnosing thymic pathology. In each case thymic shape, density, and size, particularly thickness and width, were analyzed and compared with similar data in 71 normal children with no clinical evidence of thymic abnormality. Comparison showed that most thymic diseases altered normal thymic shape and contour, and hence evaluation of gross thymic morphology alone was adequate for recognition of abnormality. Although thymic thickness was a more reliable indicator of disease than width, this measurement was rarely required for diagnosing disease. The attenuation value of the thymus was helpful occasionally in suggesting a specific diagnosis.     

CT appearances of normal and obstructed submandibular duct.

CT scans of 40 patients without pathology in the floor of the mouth or the submandibular glands were reviewed. Intraglandular ducts were visualized in 27 and extraglandular ducts in 3 patients. The CT appearances of dilated submandibular ducts are described in 4 patients with proven causes of obstruction. Widening of the narrow gutter between the mylohyoid and hyoglossus muscles in one scan level is a prominent feature. An intra- or extraglandular duct diameter of 3 mm or more indicates possible obstruction, and the CT images should be scrutinized to reveal the cause.     

新生儿颅脑正常CT表现

目的：观察新生儿颅脑正常CT表现,为新生儿颅脑疾病的诊断提供正常CT解剖依据。方法：按样本纳入标准选择60例新生儿进行颅脑CT扫描。结果：发现新生儿颅脑具有脑白质密度较低,灰白质分界模糊,硬膜窦密度高,基底池和第四脑室宽大,存在透明隔间腔等特点。结论：新生儿颅脑正常CT表现与成人明显不同,在新生儿颅脑疾病的CT诊断中,要避免将这些特殊的正常影像误诊为异常。     

Costal pleura: appearances at high-resolution CT

The appearance of the costal pleura at high-resolution computed tomography (CT) was evaluated with a cadaver and 25 normal subjects. This was contrasted with the high-resolution CT appearance of the costal pleura in 15 patients with mild pleural thickening, 13 of whom had been exposed to asbestos. On high-resolution CT scans in the normal subjects, a 1-2-mm-thick line of soft-tissue attenuation at the point of contact between lung and chest wall represents the visceral and parietal pleura, pleural contents, endothoracic fascia, and innermost intercostal muscle. In a paravertebral location, the innermost intercostal muscle is lacking, and a thin line seen on high-resolution CT scans reflects pleura and endothoracic fascia. Transverse thoracic and subcostal muscles and extrapleural fat pads can be seen as tissue internal to a rib and may be confused with pleural thickening. In 13 of the 15 patients with mild pleural thickening, the 1-3-mm-thick pleura was separable from the underlying normal intercostal muscle by a layer of extrapleural fat. High-resolution CT was more sensitive than CT with 1-cm collimation in depicting this degree of pleural abnormality.     

High-resolution computed tomography of the osseous temporomandibular joint. Some normal and abnormal appearances

A standardized CT procedure for examination of the temporomandibular joint (TMJ) with axial and coronal scanning as well as reformatted coronal and sagittal sections, was performed on 32 adults. These included subjects with normal TMJ and patients suffering from muscular dysfunction/disc displacement, arthrosis or rheumatoid arthritis. Some normal CT appearances simulating disease were presented. Axial CT scanning appeared to be the most useful method for demonstrating osseous abnormalities of the TMJ. The diagnostic information was occasionally supplemented by the coronal scanning, which may be difficult to perform on patients with neck stiffness. Reformatted coronal or sagittal sections mostly confirmed TMJ abnormality and supplemented the findings at axial scans in about one third of the patients.     

Meningeal myelomatosis: CT and MR appearances.

Meningeal myelomatosis is a rare feature of multiple myeloma. We report a case of IgG-kappa myeloma presenting as bilateral intracranial extraaxial masses.     

Synthetic ossicular replacements: normal and abnormal CT appearance

Twenty-two patients with synthetic ossicular replacements were studied with computed tomography (CT). Twelve patients had total ossicular replacement prostheses (TORPs), and ten patients had partial ossicular replacement prostheses (PORPs). Good results were achieved in 12 patients (eight with TORPs and four with PORPs). Four of these prostheses were clearly visible on CT scans, six were discernible, and two were not identified. In the ten patients with unsatisfactory surgical results, CT was performed before surgical revision. It disclosed subluxation of the prosthesis in four patients and fibrous tissue fixation in four. In two patients the CT scan appeared normal; surgery disclosed lateralization of the graft with a nonfunctioning interface.     

Parietal pleural changes in empyema: appearances at CT

The parietal pleura bordering pleural space collections was analyzed with computed tomography (CT) in 35 patients with thoracic empyema, 30 patients with malignant effusion, and 20 patients with transudatory effusion. Enhancement of the parietal pleura was present in 96% of the 25 patients with empyema who underwent contrast material-enhanced examinations. Of the 35 patients with empyema, 86% showed thickening of the parietal pleura, 60% showed thickening of the extrapleural subcostal tissues, and 35% showed increased attenuation of the extrapleural fat. None of the 20 patients with transudatory effusion showed these findings. Of the 30 patients with malignant effusion, eight patients (27%) showed chest wall changes similar to those of the patients with empyema. However, two-thirds of these patients had a recognized superimposed complication (ie, sclerotherapy). Contrast-enhanced CT appears to be sensitive to chest wall changes in patients with empyema. CT study of the parietal pleura may help suggest occult pleural space infections and may influence therapeutic decisions that vary with the stage of empyema.     

Wilms' tumour: pre- and post-chemotherapy CT appearances.

Pre-operative chemotherapy is used in our institution for patients with Wilms' Tumours (WT) when surgical 'operability' is in doubt. To date, the computed tomographic (CT) appearances of chemotherapy-induced changes in WT have not been described. We have analysed CT examinations of 18 children undergoing pre-operative chemotherapy to assess the effects of treatment on size, extent and qualitative changes of the tumour. Clinical response to chemotherapy was associated with a reduction in tumour size of at least 50%. Cystic changes were commonly seen within tumours following chemotherapy. CT did not reliably differentiate lymph nodes involved by tumour from those showing only reactive change. Pre-chemotherapy CT scans were incorrect in predicting liver invasion in 4/18 (22%) cases: of these, two were right-sided tumours, and two were bilateral.     

CT appearance of the normal and abnormal breast with mammographic correlation

Mammography is the preferred technique to evaluate the breast but computed tomography (CT) performed for extramammary disease often images breast tissue. We reviewed studies of patients who underwent both CT and mammography to identify abnormalities that were visible with both techniques. The CT appearance of the normal breast, breast cancer, and several other abnormalities is demonstrated in this study. CT may occasionally allow for a precise diagnosis of a previously unsuspected breast lesion but a mammogram is usually required.     

CT appearances of hydatid disease at various locations

Hydatid disease has characteristic imaging features on CT, which allow accurate preoperative diagnosis in most cases. However, when it occurs at unusual locations the diagnosis is often difficult, especially as the imaging appearance varies at different sites. In this article we have presented a pictorial review of the CT features of disease due to Echinococcus granulosus at various sites in the human body.     

CT appearances of rounded atelectasis.

Five patients examined with CT had lesions fulfilling criteria for a diagnosis of rounded atelectasis (RA) and these were managed without biopsy. In three patients unsuspected contralateral lesions were identified as RA variants, and one of these was biopsied at thoracotomy and proved to be benign. All patients remain well at 6-22 months follow-up. We concur with recent reports that there is a spectrum of CT appearances of RA and that even atypical lesions seldom need further investigation. We also suggest that the appearances of some atypical lesions add support for the fibrosing theory of pathogenesis of RA.     

胰头静脉弓的CT研究——正常表现及临床意义

目的：研究胰头静脉弓的ＣＴ表现，获得有关血管直径的正常值，探讨相关临床意义。材料与方法：随机选取１２９例连续性无中上腹区域恶性肿瘤及炎性病变的ＣＴ增强扫描病例，观察胰头静脉弓各属支走行及ＣＴ表现，测定血管直径。结果：胰头静脉弓属支包括胰十二指肠上后及上前静脉、胃结肠干、结肠右上静脉和胃网膜右静脉等，ＣＴ显示率分别为６３．７％、７７．５％、６９．８％、７０．５％和３４．９％；血管直径均值分别为２．２８、２．３１、４．８５、３．０１和３．８８ｍｍ。结论：正常人中上腹ＣＴ增强扫描常可清楚显示胰头静脉弓属支。对此静脉弓的认识有助于胰腺癌的术前分期及正确评估门脉系统血液动力学改变。     

The calcaneus: normal and abnormal.

The calcaneus is the largest tarsal bone. Many congenital and acquired disorders affect the bone. Primary disorders arise in the calcaneus itself, whereas secondary disorders arising in the neighboring soft tissues extend into and affect the calcaneus indirectly. Among the primary lesions, congenital, traumatic, infectious, hematologic, neoplastic, and other miscellaneous disorders constitute the majority, whereas various arthritides and soft-tissue neoplasms that arise adjacent to the bone constitute the important secondary calcaneal disorders. Radiographic features of many disorders of the calcaneus are disease-specific and thus diagnostic. This article describes a wide spectrum of calcaneal disorders and illustrates their salient radiographic features. This knowledge should facilitate radiographic diagnosis of various calcaneal disorders encountered in clinical practice.