Imaging manifestations of tropical parasitic infections.
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Diagnosis, Differential↗
Biomedical subjects
Srinivasa R Prasad
Publications and source records attributed to Srinivasa R Prasad.
Adrenal masses: CT characterization with histogram analysis method.
PURPOSE: To evaluate a histogram analysis method for differentiating adrenal adenoma from metastasis at computed tomography (CT). MATERIALS AND METHODS: In a retrospective review of 2 years of clinical CT records, 223 adrenal adenomas in 193 patients (115 with contrast material-enhanced CT, 43 with unenhanced and enhanced CT, and 35 with unenhanced CT) and 31 metastases (25 patients with enhanced CT) were found. In 158 patients with adenomas at enhanced CT, diagnosis was based on stable mass size for more than 1 year (n = 135) and characteristic signal intensity decrease at chemical shift magnetic resonance imaging (n = 23). In 35 patients with adenomas at unenhanced CT, mean attenuation was 10 HU or less. Diagnosis of all metastases was based on rapid growth of a mass or new mass in less than 6 months in patients with cancer. Adrenal metastases with extensive necrosis were excluded. Histogram analysis was performed in a circular region of interest (ROI) for mean attenuation, number of pixels, and range of pixel attenuation for all pixels and for the subset of pixels with less than 0 HU ("negative" pixels). Correlation between mean attenuation and percentage negative pixels was calculated. RESULTS: Negative pixels were present in all 74 unenhanced adenomas with mean attenuation of 10 HU or less and in 14 of 16 unenhanced adenomas with mean attenuation above 10 HU. Of 184 enhanced adenomas, only 20 had mean attenuation of 10 HU or less, but 97 contained negative pixels (77 of these 97 masses had mean attenuation above 10 HU). Increase in percentage negative pixels was highly correlated with decrease in mean attenuation of both unenhanced and enhanced adenomas. None of the adrenal metastases had mean attenuation of 10 HU or less or contained negative pixels. CONCLUSION: The histogram method is far more sensitive than the 10-HU threshold method for diagnosis of adrenal adenomas at enhanced CT, with specificity maintained at 100%.
Adenoma↗
Adult cerebral malaria: prognostic importance of imaging findings and correlation with postmortem findings.
PURPOSE: To correlate imaging abnormalities, clinical features, and postmortem findings in patients with proved cerebral malaria. MATERIALS AND METHODS: Twenty-one patients aged 17-50 years with cerebral malaria consented to undergo transverse nonenhanced (10-mm sections) and contrast material-enhanced (8-mm sections in posterior fossa and 10-mm sections in supratentorial region) CT on admission (n = 21) and on day 10 (n = 6), with thin sections (5 mm) obtained in the area of abnormality. All CT scans were evaluated for diffuse cerebral edema, focal parenchymal abnormalities, and hemorrhage. CT findings were categorized as normal, diffuse cerebral edema, and edema with thalamic hypoattenuation without or with cerebellar hypoattenuation. Spearman rank correlation test was performed. RESULTS: Initial scans were normal in seven patients with mild disease (median Acute Physiology and Chronic Health Evaluation [APACHE] II score of 7, median Glasgow Coma Scale [GCS] score of 10), and all survived. Of eight patients with diffuse cerebral edema (GCS > or = 8; median APACHE II, 21), six survived. Cerebral edema with thalamic and cerebellar white matter hypoattenuation was seen in five patients. All had GCS score of 6 or less, median APACHE II score of 26, and multiorgan failure; none survived. One patient (GCS = 6) had thalamic hypoattenuation without cerebellar lesions. He survived with mild residual hemiparesis. Diffuse petechial hemorrhages were seen in the cerebrum and cerebellum at autopsy in all seven patients who died. These petechial hemorrhages were not visualized on CT scans. CT findings did not correlate with degree of parasitemia. CONCLUSION: CT findings correlate well with level of consciousness and severity of disease but underestimate the extent of disease at pathologic examination. A normal CT scan indicates a favorable outcome, whereas cerebellar hypoattenuation portends a poor outcome.
Adolescent↗
CT tumor measurement for therapeutic response assessment: comparison of unidimensional, bidimensional, and volumetric techniques initial observations.
PURPOSE: To compare unidimensional, bidimensional, and volumetric techniques for evaluation of treatment response in patients with liver metastases from breast cancer in a phase III clinical trial. MATERIALS AND METHODS: Helical computed tomographic (CT) studies in 38 patients with liver metastases from breast cancer who were enrolled in a phase III clinical trial were evaluated before treatment and at 6 months after treatment. Two subspecialty radiologists measured all lesions on transverse CT scans with use of electronic calipers according to both unidimensional and bidimensional criteria. Volumetric measurements were made by tracing individual lesions. Measurements of individual lesions were summed to obtain patient response, which was categorized as complete response, disappearance of lesions; partial response, greater than 30% decrease in tumor diameter (unidimensional), greater than 50% reduction in tumor area (bidimensional), or greater than 65% reduction in tumor volume (volumetric); disease progression, greater than 20% increase in tumor diameter, greater than 25% increase in tumor area, or greater than 73% increase in tumor volume: or stable disease (size response other than that of complete response, partial response, or disease progression). RESULTS: In 37 patients, there was concordant treatment response with use of unidimensional and bidimensional techniques. Volumetric measurement produced results different from those of the unidimensional and bidimensional techniques in 12 and 13 patients, respectively. In six patients with partial response per unidimensional and bidimensional criteria, the response based on the volumetric technique was stable disease. In two patients with stable disease per bidimensional and unidimensional criteria, the response was partial response by volumetric measurement. In four patients with disease progression per bidimensional and unidimensional criteria, the response was stable disease per volumetric criteria. CONCLUSION: Volumetric measurement of tumor burden gives different results for treatment response compared with that of the unidimensional or bidimensional technique in a considerable proportion of patients.
Antineoplastic Combined Chemotherapy Protocols↗
Using multidetector CT for preoperative vascular evaluation of liver neoplasms: technique and results.
OBJECTIVE: The purpose of our study was to evaluate the performance of CT angiography using multidetector CT (MDCT) for preoperative vascular evaluation in candidates who were scheduled for liver neoplasm resection. SUBJECTS AND METHODS: Forty-two consecutive subjects with malignant liver tumors scheduled for resection were studied with multiphase MDCT. The first 22 subjects underwent both multiphase MDCT angiography and catheter angiography before surgery. The subsequent 20 subjects underwent only preoperative CT angiography. Postprocessing was performed, and the images were analyzed for the depiction of arterial, portal vein, and hepatic vein anatomy and for the identification of important vascular variants. The postprocessing findings were compared and correlated with the findings from catheter angiography (22/42) or intraoperative sonography (42/42) and surgery (42/42). RESULTS: Arterial anomalies were detected on the images of 17 of 42 patients, including a replaced right hepatic artery in five, replaced left hepatic artery in six, accessory right and left hepatic arteries in two, common trunk for the celiac and superior mesenteric arteries in one, and early bifurcation of the celiac artery in one. In 22 patients in whom catheter angiography confirmation was available, the number of arteries and almost all the significant anomalies were correctly identified on CT angiography (accuracy, 97%; sensitivity, 94%; specificity, 100%). In the subset of 20 patients who underwent MDCT angiography without catheter angiography confirmation, all clinically relevant information was provided by CT angiography. The portal and hepatic vein anatomy and the relationships of the liver tumors to the neighboring venous structures were shown on CT. CONCLUSION: Multidetector CT provides valuable preoperative information about hepatic vascular architecture and can be used as a noninvasive alternative to catheter angiography before oncologic liver surgery.
Adult↗
Standard-dose and 50%-reduced-dose chest CT: comparing the effect on image quality.
OBJECTIVE: CT accounts for considerable population-based radiation dose from radiographic diagnostic studies. The technical factors for CT examinations are not appropriately adjusted on the basis of patient size and anatomy. We hypothesized that radiation doses for routine chest CT can be reduced by 50% for the evaluation of normal structures without seriously jeopardizing image quality. SUBJECTS AND METHODS: After receiving institutional review board approval, we prospectively studied 24 patients with cancer who were 65 years old and older on a multidetector CT scanner. Each patient underwent imaging with four slices (centered at the carina) at the standard dose (220-280 mAs) and at 50%-reduced dose (110-140 mAs) at a constant 140 kVp. Single breath-hold scanning was performed with a 2.5-mm detector configuration, a tube rotation time of 0.8 sec, and a pitch of 6:1. Contiguous images were reconstructed at 5-mm intervals. Two subspecialty-trained chest radiologists who were unaware of the CT technique reviewed randomized images for overall image quality and anatomic detail of the structures in the lung, airway, mediastinum, and chest wall using a 5-point scale (1, worst; 2, suboptimal; 3, adequate; 4, very good; 5, excellent). The data were analyzed using the Wilcoxon's signed rank test. RESULTS: Although overall image quality was better with standard-dose CT, the quality of reduced-dose CT was acceptable. The differences in mean scores were statistically significant. There was a correlation of 0.59 between observers. The mean scores of standard-dose CT were always greater than or equivalent to those of low-dose CT for both observers. The assessment of great vessels and soft tissue of the chest wall contributed mainly to the differences in image quality. Both the central and peripheral lung parenchyma and the airway were adequately visualized on low-dose CT. Radiation doses (based on weighted-CT-dose index) from standard-dose CT and 50%-reduced-dose CT were 15.6-21.4 mSv and 7.8-10.7 mSv, respectively (from the manufacturer's data). CONCLUSION: Chest CT image quality appears to be acceptable for evaluating normal anatomic structures even with a 50% reduction in radiation dose.
Aged↗
Functioning acinar cell pancreatic carcinoma: diagnosis on mangafodipir trisodium (Mn-DPDP)-enhanced MRI.
We describe the imaging findings of a functional pancreatic acinar cell carcinoma in a patient who presented with weight loss, hyperlipasemia, and multiple foci of subcutaneous fat necrosis. The tumor invaded the adjacent splenic and portal vein, causing isolated left-sided portal hypertension. At MRI, the tumor showed marked enhancement following administration of the hepatobiliary-specific contrast agent mangafodipir trisodium (Mn-DPDP), thereby demonstrating the functional nature of the tumor. Avid uptake of Mn-DPDP by a functioning pancreatic tumor has not been reported in the radiology literature.
Aged↗
CT characterization of "indeterminate" renal masses: targeted or comprehensive scanning?
PURPOSE: A comprehensive renal mass evaluation CT protocol is usually performed for simultaneous characterization and staging of incidentally discovered renal masses considered indeterminate on ultrasound (US). The purpose of the study was to determine if a comprehensive examination is appropriate in these patients. MATERIALS AND METHODS: The authors performed a retrospective review of 100 patients (mean age, 61 years) with 102 sonographically indeterminate renal masses and who were referred to undergo CT for lesion characterization. Lesions were classified according to surgical histology or imaging follow-up evaluation. Statistical analysis was performed. RESULTS: Thirteen lesions (12.7%) in 11 (11%) patients (mean age, 59 years) were malignant. Eighty-seven lesions (85.3%) in 87 patients (87%; mean age, 62 years) were benign. Two lesions (1.96%) in two patients (2%) remained indeterminate. CONCLUSION: Although comprehensive renal mass evaluation protocol provides a more thorough patient evaluation, only a small fraction of indeterminate renal masses seen on US are malignant. The authors' results suggest a targeted renal CT imaging protocol for evaluation of indeterminate renal masses incidentally discovered on US.
Adult↗
Comparison between low (3:1) and high (6:1) pitch for routine abdominal/pelvic imaging with multislice computed tomography.
PURPOSE: The purpose of this study was to compare the performance of low helical pitch acquisition (3:1) and high helical pitch acquisition (6:1) for routine abdominal/pelvic imaging with multislice computed tomography (CT). METHOD: Three hundred eighty-four patients referred for abdominal/pelvic CT were examined in a breath-hold on a multislice CT scanner (LightSpeed QX/I; General Electric Medical Systems, Milwaukee, WI). Patients were randomized and scanned with pitch of 3:1 or 6:1 using a constant 140 peak kV and 280-300 mA. Images were reconstructed at a 3.75-mm slice thickness. Direct comparison between the two pitches was possible in a subset of 40 patients who had a follow-up scan performed with the second pitch used in each patient. A comparison was also performed between standard dose CT using a pitch of 6:1 and 20% reduced radiation dose CT using a pitch of 3:1. Two readers performed a blind evaluation using a three-point scale for image quality, anatomic details, and motion artifacts. Statistical analysis was performed using a rank sum test and the Wilcoxon signed rank test. RESULTS: Overall image quality mean scores were 2.5 and 2.3 for a pitch of 3:1 and a pitch of 6:1, respectively (P = 0.134). Likewise, mean anatomic detail and motion artifact scores were 2.5 and 2.6 for a 3:1 pitch and 2.3 and 2.5 for a 6:1 pitch, respectively (P > 0.05). In patients with a direct comparison of the two pitches (with the standard radiation dose as well as with a 20% reduction in milliamperes), no statistically significant difference in the performance of the two pitches was observed (P > 0.05). CONCLUSION: Image quality with a high pitch (6:1) is acceptable for routine abdominal/pelvic CT.
Adult↗
Radiological measurement of breast cancer metastases to lung and liver: comparison between WHO (bidimensional) and RECIST (unidimensional) guidelines.
PURPOSE: Radiologic assessment of "response-to-treatment" during clinical trials of anticancer drugs has been conventionally based on bidirectional tumor measurement. Recently, the revised guidelines were published, which recommended unidirectional tumor measurements. The purpose of this study was to compare response to treatment between the two measurement techniques in breast cancer patients with lung and liver metastases. METHOD: Contrast-enhanced computed tomography studies of 86 breast cancer patients who had lung (n = 27) and liver (n = 59) metastases and who were enrolled in a phase-III oncology trial were evaluated before initiation of treatment and at 6 months after treatment. Lesions were measured by subspecialist radiologists on digitized images using electronic calipers. The largest diameter of the lesions was extracted from bidimensional measurements. Response to treatment was categorized into one of four categories: complete response indicating lesion disappearance, partial response indicating >30% decrease in tumor diameter, or >50% reduction in tumor area, disease progression indicating >20% increase in tumor diameter, or >25% increase in tumor area, and stable disease (neither complete response, partial response, nor disease progression). Response to treatment between the two measurement techniques was compared statistically using the chi2 test. RESULTS: Response to treatment was concordant in 76 patients between unidimensional and bidimensional measurement techniques. In 5 patients (2 lung and 3 liver metastases) the response assessment was improved using unidimensional criteria and in 5 patients (2 lung and 3 liver metastases) the response was worse using unidimensional guidelines. Thus, the overall response rate was 50% for both unidimensional and bidimensional measurement techniques. There was no statistical difference between the two techniques. CONCLUSION: Unidimensional measurements are appropriate for measuring the size of liver and lung metastases for determining response to treatment during clinical testing of oncologic drugs.
Antineoplastic Agents↗
Endovaginal magnetic resonance imaging of the female urethra.
Magnetic resonance imaging (MRI) is playing an important role in the clinical evaluation of women presenting with urethral symptoms. Voiding cystourethrography, direct urethrography, and pelvic sonography provide limited information on abnormalities that are in continuity with the urethra. On the other hand, urethra and periurethral tissues can be noninvasively evaluated by high-resolution endocavitary MRI. Because of its multiplanar capability and high tissue contrast, endovaginal MRI is an extremely reliable diagnostic test in the evaluation of urethral abnormalities. In this article, the utility of endovaginal MRI in the detection and characterization of a wide spectrum of urethral pathologic conditions, such as congenital anomalies, diverticula, urethritis, and benign and malignant neoplasms, is discussed.
Female↗
Neoplasms of the renal medulla: radiologic-pathologic correlation.
Tumors of the renal medulla cover a wide spectrum, with characteristic histomorphology and variable biologic profiles. Renal medullary tumors can be categorized into benign and malignant neoplasms based on histologic features and clinico-biologic behavior. They can be further classified into pediatric and adult tumors based on the patient age group. When small, renal medullary tumors may be differentiated from the more common renal adenocarcinomas by their central location and certain demographic characteristics. Although most large malignant medullary tumors demonstrate imaging findings that are indistinguishable from those of other renal malignancies, some tumors demonstrate imaging findings that may suggest a specific diagnosis.
Humans↗
Fat-containing lesions of the liver: radiologic-pathologic correlation.
Fat-containing tumors of the liver are a heterogeneous group of tumors with characteristic histologic features, variable biologic profiles, and variable imaging findings. Benign liver lesions that contain fat include focal or geographic fatty change (steatosis), pseudolesions due to postoperative packing material (omentum), adenoma, focal nodular hyperplasia, lipoma, angiomyolipoma, cystic teratoma, hepatic adrenal rest tumor, pseudolipoma of the Glisson capsule, and xanthomatous lesions in Langerhans cell histiocytosis. Malignant liver lesions that can contain fat include hepatocellular carcinoma, primary and metastatic liposarcoma, and hepatic metastases. Identification of fat within a liver lesion can be critical in characterization of the lesion. The imaging characteristics of a lesion coupled with the pattern of intratumoral fatty change are helpful in narrowing the differential diagnosis. Although the presence of fat can be demonstrated with computed tomography or ultrasound, magnetic resonance imaging is the most specific imaging technique for demonstration of both microscopic and macroscopic fat.
Fatty Liver↗
Cross-sectional imaging of the female urethra: technique and results.
Clinical assessment of women with urethral symptoms is difficult, necessitating further evaluation with imaging. Urethrography provides limited information on luminal abnormalities of the urethra. Recent advances in ultrasound (US) and magnetic resonance (MR) imaging have dramatically improved evaluation of the female urethra, clarifying findings at physical examination and providing accurate road maps for surgeons. High-resolution transvaginal US, transperineal US, and transurethral US are reliable techniques for diagnosis and characterization of urethral abnormalities. High-resolution multiplanar MR imaging with phased-array pelvic and endovaginal coils demonstrates the urethral anatomy in greater detail. In women with urethral diverticula, US and MR imaging demonstrate the number of diverticula and the location, size, configuration, and possible contents of the sac. Most important, the position of the neck of the diverticulum may be identified for the surgeon. Imaging features do not allow differentiation between histologic subtypes of urethral carcinoma; the diagnosis is established with histopathologic examination. Periurethral cysts do not communicate with the urethra and therefore can often be differentiated from urethral diverticula at endocavitary MR imaging. High-resolution multiplanar US and MR imaging allow comprehensive evaluation of abnormalities of the female urethra.
Female↗
Informatics in radiology (infoRAD): introduction to the language of three-dimensional imaging with multidetector CT.
The recent proliferation of multi-detector row computed tomography (CT) has led to an increase in the creation and interpretation of images in planes other than the traditional axial plane. Powerful three-dimensional (3D) applications improve the utility of detailed CT data but also create confusion among radiologists, technologists, and referring clinicians when trying to describe a particular method or type of image. Designing examination protocols that optimize data quality and radiation dose to the patient requires familiarity with the concepts of beam collimation and section collimation as they apply to multi-detector row CT. A basic understanding of the time-limited nature of projection data and the need for thin-section axial reconstruction for 3D applications is necessary to use the available data effectively in clinical practice. The axial reconstruction data can be used to create nonaxial two-dimensional images by means of multiplanar reformation. Multiplanar images can be thickened into slabs with projectional techniques such as average, maximum, and minimum intensity projection; ray sum; and volume rendering. By assigning a full spectrum of opacity values and applying color to the tissue classification system, volume rendering provides a robust and versatile data set for advanced imaging applications.
Imaging, Three-Dimensional↗
Common and uncommon histologic subtypes of renal cell carcinoma: imaging spectrum with pathologic correlation.
Renal cell carcinoma (RCC) is a cause of significant morbidity and mortality, with an estimated 35,000 new cases and 12,480 deaths in the United States in 2003. Recent advances in imaging technology, pathology, urology, and oncology permit early diagnosis of RCC and facilitate optimal management. The 2004 World Health Organization classification for renal neoplasms recognizes several distinct histologic subtypes of RCC. These subtypes include clear cell RCC, papillary RCC, chromophobe RCC, hereditary cancer syndromes, multilocular cystic RCC, collecting duct carcinoma, medullary carcinoma, mucinous tubular and spindle cell carcinoma, neuroblastoma-associated RCC, Xp11.2 translocation-TFE3 carcinoma, and unclassified lesions. Different histologic subtypes of RCC have characteristic histomorphologic and biologic profiles. Clear cell RCC is the most common subtype and has a less favorable prognosis (stage for stage) than do papillary RCC and chromophobe RCC. Collecting duct carcinoma and renal medullary carcinoma are associated with aggressive clinical behavior and a poor prognosis.
Carcinoma, Renal Cell↗
Correlation of patient weight and cross-sectional dimensions with subjective image quality at standard dose abdominal CT.
OBJECTIVE: We evaluated the association between patients' weight and abdominal cross-sectional dimensions and CT image quality. MATERIALS AND METHODS: We prospectively evaluated 39 cancer patients aged more than 65 years with multislice CT scan of abdomen. All patients underwent equilibrium phase contrast-enhanced abdominal CT with 4 slices (from top of the right kidney) obtained at standard tube current (240-280 mA). All other scanning parameters were held constant. Patients' weight was measured just prior to the study. Cross-sectional abdominal dimensions such as circumference, area, average anterior abdominal wall fat thickness and, anteroposterior and transverse diameters were measured in all patients. Two subspecialty radiologists reviewed randomized images for overall image quality of abdominal structures using 5- point scale. Non-parametric correlation analysis was performed to determine the association of image quality with patients' weight and cross-sectional abdominal dimensions. RESULTS: A statistically significant negative linear correlation of 0.46, 0.47, 0.47, 0.58, 0.56, 0.54, and 0.56 between patient weight, anterior abdominal fat thickness, anteroposterior and transverse diameter, circumference, cross-sectional area and image quality at standard scanning parameters was found (p<0.01). CONCLUSION: There is a significant association between image quality, patients' weight and cross-sectional abdominal dimensions. Maximum transverse diameter of the abdomen has the strongest association with subjective image quality.
Aged↗