Renal lymphoma: CT patterns with emphasis on helical CT.

Renal lymphoma is most often seen in conjunction with multisystemic, disseminated lymphoma or as tumor recurrence. Renal lymphoma may also be seen in immunocompromised patients or, rarely, as primary disease. Computed tomography (CT) is the most sensitive, efficient, and comprehensive examination for evaluation of the kidneys in patients with suspected renal lymphoma. Helical CT in particular improves detection and characterization of lymphomatous renal involvement by optimizing contrast dynamics and data acquisition and is the current modality of choice for accurate staging of lymphoma. Typical CT patterns in renal lymphoma include single and multiple masses, invasion from contiguous retroperitoneal disease, perirenal disease, and diffuse renal infiltration. Atypical CT patterns may also be encountered and provide a diagnostic challenge. These include spontaneous hemorrhage, necrosis, heterogeneous attenuation, cystic transformation, and calcification. Solid renal masses including renal cell carcinoma and metastases are the most commonly encountered entities that mimic renal lymphoma at CT and require biopsy for definitive diagnosis. CT (particularly helical CT) is useful in the evaluation of patients with suspected renal lymphoma, and familiarity with the spectrum of findings in renal lymphoma is important for accurate diagnosis.     

Lung cancers missed at low-dose helical CT screening in a general population: comparison of clinical,histopathologic, and imaging findings

PURPOSE: To compare clinical, histopathologic, and imaging features of lung cancers missed at low-radiation-dose helical computed tomography (CT). MATERIALS AND METHODS: Eighty-three primary lung cancers were found during an annual low-dose CT screening program and confirmed histopathologically at either surgery or biopsy. Thirty-two of these lung cancers were missed on 39 CT scans: on 23 scans owing to detection errors and on 16 owing to interpretation errors. The clinical characteristics, CT features, and histopathologic findings of these missed lung cancers were correlated. RESULTS: All missed cancers were intrapulmonary, and 28 (88%) were stage IA. All 20 detection errors occurred in cases of adenocarcinoma, 17 (85%) of which were well-differentiated tumors and 11 (55%) of which were in nonsmoking women. The mean size of cancers missed owing to detection error, 9.8 mm, was smaller than that of cancers missed owing to interpretation error, 15.9 mm (P <.001). In the detection error group, the percentages of nodules with ground-glass opacity (91%) or judged to be subtle (91%) were greater than those of nodules in the interpretation error group (38% and 25%, respectively) (P <.001). In the detection error group, 83% (19/23) of cancers were overlapped with, obscured by, or similar in appearance to normal structures such as pulmonary vessels. On 14 of the 16 CT scans with which there were interpretation errors, the CT findings mimicked benign disease, and the patients also had underlying lung disease, such as tuberculosis, emphysema, or lung fibrosis. CONCLUSION: The lung cancers missed at low-dose CT screening in this series generally were very subtle and appeared as small faint nodules, overlapping normal structures, or opacities in a complex background of other disease.     

Temporal bone: three-dimensional CT. Part I. Normal anatomy, techniques, and limitations

Three-dimensional (3D) surface renderings of the temporal bone were created from routine axial computed tomographic (CT) images in 15 subjects and in cadaver specimens. The displayed anatomy was correlated with these specimens, as well as with images from the routine study. Six sets of viewing angles were derived for optimal display of surgically important surface landmarks, such as the suprameatal triangle and supramastoid crest. The 3D CT images were found to be of excellent quality and permitted a global view of the temporal bone surface anatomy. Bone depletion artifacts ("pseudoforamina") posed a potentially serious problem in evaluating the tegmen and wall of the sigmoid sulcus, being present in eight of 20 cases. Three-dimensional CT may be a useful adjunct to routine temporal bone imaging.     

CT evaluation of appendicitis and diverticulitis. Part I: Appendicitis

CT has become the primary imaging modality for evaluation of possible appendicitis. About 20 % of patients taken to surgery for appendicitis without CT have had a normal appendix removed. CT has demonstrated overall accuracy of between 93 % and 98 %. Alternative diagnoses are seen in 34–80 % of patients without appendicitis but who were suspected of having appendicitis. For evaluation of appendicitis different techniques have been successful, including the use of no contrast, use of oral and intravenous contrast, and use of rectally administered contrast. Scanning of the entire abdomen and pelvis and scanning of an area limited to the right lower quadrant are also options. Ultrasonography has been shown to have a role in pediatric patients. If ultrasonography is positive, CT is not necessary. If ultrasonography is negative, CT should follow.     

CT of thoracic lymph nodes. Part I: anatomy and drainage

CT is the primary non-invasive technique for the diagnostic evaluation of thoracic lymph nodes. The CT patterns and anatomic location of thoracic lymph node involvement can provide important clues in the diagnosis of many diseases. Part I of the pictorial review illustrates the anatomic location and drainage of thoracic lymph nodes in the chest wall, mediastinum and lungs through examples of pathologic involvement. Part II of the pictorial review focuses on CT patterns of lymph node involvement in various pulmonary and extrapulmonary diseases, differential diagnoses based on CT findings and pitfalls.     

CT perfusion in solid-body tumours. Part I: technical issues

Functional imaging is becoming increasingly important in both research and clinical diagnostic radiology. Perfusion computed tomography (CTP) is a readily available and widely used tool that allows an objective measurement of tissue perfusion through the mathematical analysis of data obtained from repeated scans performed after administration of contrast agent. Recently, CTP has been increasingly used in the oncological field, being studied as a potential marker of neoplastic angiogenesis, which is one of the main targets of new tumour therapies. The aim of this paper was to provide the theoretical background and practical guidance for accurately performing CTP and interpreting results of examinations in solid-body tumours. CTP could be a valid tool for functional imaging of tumours if the acquisition technique is robust, if image and data analysis is accurate and if interpretation of results is adequately inserted within a clinical context.     

Suspected ureteral colic: primary helical CT versus selective helical CT after unenhanced radiography and sonography.

OBJECTIVE: The purpose of this study was to compare the accuracy of unenhanced helical CT with combined sonography and unenhanced radiography in patients with acute flank pain suggestive of ureteral colic. SUBJECTS AND METHODS: From January 1997 to December 1999, 181 consecutive patients with acute flank pain underwent unenhanced radiography, sonography, and unenhanced helical CT (protocol A). From January 2000 to December 2000, 96 consecutive patients arriving at the emergency department with acute flank pain were alternately submitted either to primary unenhanced helical CT (protocol B, 48 patients) or to unenhanced radiography and sonography with the addition of helical CT in unclear cases (protocol C, 48 patients). RESULTS: When compared with the diagnostic accuracy for ureterolithiasis of the combined sonography and radiography in the same group of subjects (protocol A), CT had a greater sensitivity (92% vs 77%), negative predictive value (87% vs 68%), and overall accuracy (94% vs 83%). Among patients who underwent primary CT (protocol B), we found three false-negatives (all with spontaneous stone passage) and no false-positives. Among patients initially examined with unenhanced radiography and sonography (protocol C), we found one false-positive (leading to patient admission and needless repeated radiographic and sonographic studies) and six false-negatives (all followed by an uncomplicated course and spontaneous passage); CT depicted four of these stones but did not result in change in treatment. Fourteen percent of the patients in protocol C required invasive treatment, but combined sonography and radiography showed stones and hydronephrosis in all these patients. CONCLUSION: Unenhanced CT was the most accurate modality for determining the presence of ureterolithiasis. The combination of abdominal radiography and sonography, however, yielded comparable results with no clinically important misdiagnoses and thus can be used as an alternative when CT resources are limited.     

CT结肠成像筛查检出意外的肠外病变:临床和经济影响

目的在大量筛查人群中,评价CT结肠成像发现结肠外病变的几率并评估额外检查费用。方法本回顾性研究通过机构审查委员会批准。本研究包括2195例无症状的     

Radiotherapy planning: direct tumor location on simulation and port films using CT. Part I. Principles

Although there have been great advances in cancer diagnosis in recent years, it remains difficult to transfer tumor location information from cross-sectional computed tomographic (CT) scans or magnetic resonance images to the simulation and verification films used in planning radiotherapy. A newly developed system uses radioopaque markers attached to the patient as reference points. These markers are identified on both CT scans and simulation films and their locations entered into the treatment planning computer. The tumor and any desired normal structures are then outlined manually on each CT section. Transparent overlays produced by the computer show the position of the reference markers and tumor outlines for any combination of gantry angles and source-film distance. Because the overlays are scaled to the simulation films, the reference points enable precise alignment of overlay and film. The tumor outline thus appears on the simulation or verification films exactly as it is "seen" by the therapy beam, making field verification straightforward and accurate, even on oblique films.     

Demonstration of aberrant hepatic and gastric arteries with helical CT.

RATIONALE AND OBJECTIVES: To assess the demonstration of aberrant hepatic and gastric arteries with routine axial biphasic helical CT. METHODS: The arterial-phase images of biphasic helical CT were reviewed to evaluate aberrant hepatic and gastric arteries in 166 patients with hepatocellular carcinomas. Biphasic (30 and 70 seconds) helical CT was performed with 10 mm of collimation. The results were compared with angiography performed within 2 weeks after this CT. RESULTS: Aberrant hepatic arteries were identified by CT in 38 patients and by angiography in 43 patients (38/43, 88%). Aberrant left gastric arteries were identified in three patients by angiography and by CT (3/3). Careful observation of the fissure for the ligamentum venosum and portacaval space was useful for the detection of these arteries. CONCLUSIONS: Aberrant hepatic and gastric arteries were well demonstrated with routine axial biphasic helical CT. This may be useful for the surgical and transcatheter management of hepatic tumors.     

Ethmoid sinus disease: CT evaluation in 400 cases. Part I. Nonsurgical patients

The unique anatomy of the ethmoid sinuses makes it difficult to interpret "soft-tissue clouding," especially on plain films. The clinical significance of isolated or generalized soft-tissue disease within ethmoid cells is unclear, and the patterns of bone erosion or remodeling must be relied on in establishing a specific differential diagnosis. Of 400 patients studied, 186 had inflammatory disease and 214 had tumors. Squamous cell carcinomas, metastases, and a few aggressive sarcomas were found almost exclusively to have bone destruction, while 94% of the remaining neoplasms were characterized by cavity remodeling. Further differentiation was sometimes possible because of the pattern and degree of tumor enhancement. Of the neoplasms, only the minor salivary gland lesions and neuromas had nonhomogeneous enhancement. Malignant lesions cannot be diagnosed with computed tomography (CT) unless bone destruction is present. Similarly, although the significance of persistent, benign-appearing soft-tissue disease during chemotherapy is unclear, tumor must always be suspected, even after many months of a stable CT appearance.