Non-contrast-enhanced Computed Tomography Research Articles

Intravenous Contrast Agent Influence on Thoracic Computed Tomography Simulation Investigated Through A Heterogeneous Dose Calculation Method Using 5-Bulk Densities

Using 5-bulk-density heterogeneous dose calculation, we investigated whether contrast-enhanced (CE+) computed tomography (CT) will affect dose-calculation accuracy in the thoracic area. We analyzed 17 radiation-oncology patients who underwent thoracic CE+ CTs. Full-resolution CT and 5-bulk-density plans were generated using an adaptive convolution algorithm. Bulk densities for air, lung, fat, soft tissue, and bone were applied to regions identified by an isodensity segmentation tool. The population-averaged physical density of each region was calculated and compared with the reference value calculated from 66 noncontrast-enhanced (CE-) thoracic CT images. Using the 5-bulk densities, we created a new plan in which the physical densities of each area were forced to be the same as the CE- reference value, and we compared the dose-volume histograms (DVH). Average physical density for the segmented air, lung, fat, soft tissue, and bone for CE+ were 0.14, 0.29, 0.90, 1.03, and 1.13 g/cm(3), and the reference values for CE- were 0.14, 0.26, 0.89, 1.02, and 1.12 g/cm(3), respectively. In all the cases, the normal-tissue DVH agreed to better than 1%. In 15 cases, DVH of the planning target volume (PTV) agreed to better than 3%. In 2 patients, >3% difference in the PTV dose was observed. Only 2 patients with a strong injection artifact in the PTV or beam showed >3% discrepancy in the target dose. When using CE+ CT for treatment planning, strong injection artifacts must be excluded.

Non-contrast Computed Tomography After Percutaneous Nephrolithotomy: Findings and Clinical Significance

To describe the post-percutaneous nephrolithotomy (PNL) non-contrast-enhanced computed tomography (NCCT) findings and assessed their clinical significance. NCCT evaluates stone clearance after PNL and also reveals procedure-related changes. One hundred consecutive patients who underwent PNL were evaluated by NCCT one day post-procedure. Two radiologists analyzed the type and severity of the NCCT findings, which were then statistically analyzed in relation to the patient's clinical course. The patients' mean age was 54 years (range 18-82) and the mean maximal stone diameter was 37 mm (range 15-70). The median operative time was 110 minutes for an immediate stone-free rate of 83%, changing to 94% (P = .073) after a second-look PNL in 11 patients. The post-PNL NCCT findings were hydronephrosis (70%), atelectasis (54%), ipsilateral pleural effusion (52%), paracolic gutter fluid (44%), perinephric hematoma (40%), perinephric fluid (32%), ureteronephrosis (31%), renal swelling (23%), contralateral pleural effusion (22%), residual fragments (RFs) (17%), subcapsular hematoma (10%), and flank hematoma (6%). Univariate analysis revealed a significant association with clinical variables for all NCCT findings except for atelectasis, ureteronephrosis, contralateral pleural effusion, RFs, and flank hematoma. In multivariate analysis, only perinephric fluid (P = .007) and ipsilateral pleural effusion (P = .034) were associated with longer hospitalization, and perinephric fluid with longer recovery (P = .004). The complication rate was 12%, but none were linked with the radiological findings. This work describes the post-PNL NCCT findings and their clinical significance. Perinephric fluid and ipsilateral pleural effusion were found to independently predict longer hospitalization and recovery time.

Hyperdensity on non-contrast CT immediately after intra-arterial revascularization

Non-contrast enhanced computed tomography (NCCT) is usually performed to estimate bleeding complications immediately after procedures. However, hyperdense areas on NCCT have not yet been understood; different interpretations have been reported in the literature. It remains unclear whether NCCT performed immediately after intra-arterial revascularization (IAR) could be useful for predicting hemorrhagic transformation (HT) or clinical outcomes. Therefore, we investigated the diagnostic values of hyperdense areas on NCCT images obtained immediately after IAR. This was a retrospective study of acute ischemic stroke patients who underwent IAR between October 2007 and December 2010. NCCT scans were routinely obtained immediately after IAR and additional follow-up imaging protocols included diffusion weighted imaging (DWI)/gradient echo imaging (GRE) 24 h after IAR. HT was assessed by means of GRE obtained 24 h after IAR. Hounsfield Unit (HU) of the hyperdensity was measured in the manually drawn regions of interest. A total of 68 patients were analyzed in this study. Twenty-nine patients (42.6%) developed HT on follow-up images. Thirty-eight patients had hyperdense areas on NCCT immediately after IAR. Hyperdensity on NCCT performed immediately after IAR revealed 23 (60.5%) of the 38 patients with six false negative areas. NCCT performed immediately after IAR showed a sensitivity of 79.3%, a specificity of 61.5%, a positive predictive value of 60.5% and a negative predictive value of 80% for HT. The HU value was a predictor of HT without statistical significance (area under curve of 0.629; 95% CI: 0.49-0.76; p = 0.068). In addition, an HU of >90 poorly predicted HT with a low sensitivity (23%) and a high specificity (94%). In conclusion, our results showed that although hyperdensity on NCCT images obtained immediately after IAR had a moderate predictive value for HT, there were limitations to the prediction of subsequent parenchymal hematoma and symptomatic intracranial hemorrhage, with a low specificity and a low positive predictive value.

Are Stone Protocol Computed Tomography Scans Mandatory for Children With Suspected Urinary Calculi?

To examine the clinical utility of noncontrast-enhanced computed tomography (NCCT) in pediatric patients with urolithiasis who progressed to surgery. Although NCCT is routine for the evaluation of adult patients with suspected urolithiasis, its routine use in the pediatric population is tempered by concern about radiation exposure. We conducted a retrospective chart review of all pediatric patients who had undergone surgery for urinary stones from 2003 to 2008 at our institution. The imaging modalities used, surgery type, stone composition, 24-hour urinalyses, and relevant predisposing conditions were characterized. A total of 42 pediatric patients (24 males and 18 females) were treated during the 6-year period. The average age was 11.3±5.3 years (range 2.7-25.4), and the most common treatment modalities were shock wave lithotripsy (28%) and ureteroscopy (22%). A discernible risk factor or cause of urolithiasis was absent in 21 patients (47%). A review of imaging studies found 38 with stones visible on ultrasonography and/or abdominal plain film. A total of 21 patients underwent NCCT, in addition to ultrasonography and/or abdominal plain film. Of these, only 5 patients required NCCT for the diagnosis or management of their stone. Nearly 90% of pediatric patients treated for symptomatic urolithiasis could have completed their evaluation and treatment without undergoing NCCT. For children who present with signs and symptoms suggesting urinary calculi, an initial evaluation and imaging with ultrasonography and abdominal plain film might suffice, avoiding the radiation of NCCT.

Comparison of contrast-enhanced CT, PET/CT, PET, and low-dose non-contrast enhanced CT imaging of diffuse large B-cell (DLBCL), follicular (FL), small lymphocytic/CLL (CLL/SLL), and marginal zone lymphomas (MZL).

8079 Background: Anatomic imaging by contrast-enhanced computed tomography (CECT), functional imaging by 18FDG- PET (PET), and low-dose non-contrast enhanced CT (NECT) co-registered with PET (PET/CT) is used for detection of lymphomas. We compared the sensitivity of detection of specific lymphomas for each of these imaging modalities. Methods: Patients (pts) with DLBCL, FL, CLL/SLL, or MZL with PET/CT and CECT studies performed at our institution within 6 weeks of each other without intervening therapy were studied. Radiologists, blinded to clinical information and other imaging results, separately interpreted image sets of NECT, PET, fusion PET/CT, and CECT studies. The presence or absence of disease at 44 nodal and 48 (female) / 49 (male) extranodal sites was recorded for each site for each imaging modality. Concordant findings across imaging modalities were defined as positive for involvement by lymphoma; discordant findings were reconciled using all available clinical and radiologic information with follow-up for progression or regression of abnormality, or by biopsy. Results: 56 pts with DLBCL (n=31), FL (n=13), CLL/SLL (n=5), and MZL (n=7) had image sets available for review; 305 sites met criteria for involvement by lymphoma (DLBCL = 89, FL = 98, MZL = 45, CLL/SLL = 73). PET/CT had a higher sensitivity of lymphoma detection than CECT in DLBCL (difference in sensitivity 28% [95%CI 15-40], p < 0.0002) and FL (difference in sensitivity 12% [95%CI: 1-23], p = 0.02). CECT had a higher sensitivity of lymphoma detection than PET/CT in MZL (difference in sensitivity 18% [95%CI 1-34], p = 0.035) and CLL/SLL (difference in sensitivity 34% [95%CI 19-48], p < 0.0002). CECT had a higher sensitivity than NECT in FL (difference in sensitivity = 26% [11-38], p < 0.0002), MZL (difference in sensitivity 22% [95%CI 5-38], p = 0.011), and CLL/SLL (difference in sensitivity = 25% [95%CI 5-38], p < 0.0004), but not in DLBCL. Conclusions: The optimal modality for imaging lymphoma depends on the specific lymphoma. For DLBL and FL, PET/CT is superior to CECT. Conversely, CECT is superior to PET/CT imaging in CLL/SLL and MZL. No significant financial relationships to disclose.

Automated aortic calcium scoring on low‐dose chest computed tomography

Thoracic computed tomography (CT) scans provide information about cardiovascular risk status. These scans are non-ECG synchronized, thus precise quantification of coronary calcifications is difficult. Aortic calcium scoring is less sensitive to cardiac motion, so it is an alternative to coronary calcium scoring as an indicator of cardiovascular risk. The authors developed and evaluated a computer-aided system for automatic detection and quantification of aortic calcifications in low-dose noncontrast-enhanced chest CT. The system was trained and tested on scans from participants of a lung cancer screening trial. A total of 433 low-dose, non-ECG-synchronized, noncontrast-enhanced 16 detector row examinations of the chest was randomly divided into 340 training and 93 test data sets. A first observer manually identified aortic calcifications on training and test scans. A second observer did the same on the test scans only. First, a multiatlas-based segmentation method was developed to delineate the aorta. Segmented volume was thresholded and potential calcifications (candidate objects) were extracted by three-dimensional connected component labeling. Due to image resolution and noise, in rare cases extracted candidate objects were connected to the spine. They were separated into a part outside and parts inside the aorta, and only the latter was further analyzed. All candidate objects were represented by 63 features describing their size, position, and texture. Subsequently, a two-stage classification with a selection of features and k-nearest neighbor classifiers was performed. Based on the detected aortic calcifications, total calcium volume score was determined for each subject. The computer system correctly detected, on the average, 945 mm3 out of 965 mm3 (97.9%) calcified plaque volume in the aorta with an average of 64 mm3 of false positive volume per scan. Spearman rank correlation coefficient was p = 0.960 between the system and the first observer compared to p = 0.961 between the two observers. Automatic calcium scoring in the aorta thus appears feasible with good correlation between manual and automatic scoring.

Clinical value of computed tomography perfusion source images in acute stroke

Computed tomography perfusion (CTP) map can sensitively and accurately distinguish between infarct core and ischemic penumbra. However, CTP mapping software might not generate a perfusion map because of head movement; thus, analysing CTP source images (CTP-SI) is necessary in this situation to provide information for stroke diagnosis and therapy. In our work, 'one-stop shop' computed tomography (CT) examination including non-contrast-enhanced CT (NCCT), CTP, CT angiography (CTA) were performed in 24 patients with symptoms of acute stroke less than 9 hours. We divided patients into two groups (with and without delayed perfusion on CTP-SI), and compared the Alberta Stroke Program Early CT Score (ASPECTS) on CTP-SI and CTA-SI with follow-up imaging. Using follow-up imaging ASPECTS as the final infarct size, our results suggests that the ASPECTS of both CTP-SI and CTA-SI effectively predict final infarct core in the group without delayed perfusion, whereas CTP-SI has a potential advantage over CTA-SI in being able to predict final infarct core in the group with delayed perfusion. In conclusion, CTP-SI provides useful complementary information when CTP map software could not generate perfusion maps.

CT Diagnosis of Cerebral Venous Thrombosis: Importance of the First Examination for Fast Treatment

This study is a retrospective investigation of the role of non contrast-enhanced CT (NCCT) in the diagnosis of cerebral venous thrombosis (CVT) in clinical practice. We retrospectively identified 24 patients discharged with a diagnosis of CVT between January 2002 and December 2008 who had undergone NCCT as the first imaging modality. NCCT had been evaluated by a general radiologist and subsequently by a neuroradiologist in five cases. Final diagnosis was established by CT angiography (CTA), magnetic resonance (MR) and digital subtraction angiography (DSA). NCCT diagnosis was defined as "positive" when the neuroradiologist suggested the diagnosis of CVT on the report, as opposed to the "negative" diagnosis group. All NCCT examinations were reviewed by a neuroradiologist experienced in cerebrovascular pathology. We compared his evaluation and analysed the location and number of direct signs found on NCCT. The neuroradiologist strongly suggested an NCCT diagnosis of CVT in 63% (15/24) of patients: 80% (4/5) with deep venous thrombosis (DVT) and 57% (11/19) with sinus venous thrombosis (SVT). The general radiologist's NCCT evaluation was incorrect in four cases, subsequently diagnosed at NCCT by the neuroradiologist. After reviewing the NCCT examination the experienced neuroradiologist identified the CVT direct sign in two that belonged to the NCCT negative diagnosis group. Thus the direct sign was present in 71% (17/24) of the cases: all the patients with DVT and 63% (12/19) of the patients with SVT. NCCT still plays an important role for fast and accurate diagnosis of CVT in the emergency setting. NCCT displayed the CVT direct sign more frequently than previously thought and it was correctly interpreted in most cases. Neuroradiological consultation adds value to the general radiologist's evaluation.

Application of a new mismatch model on evaluating infarct core and penumbra in acute ischemic stroke using CT perfusion source images

Objective To assess the diagnostic value of determining infarct core and penumbra using CT perfusion source images (CTP-SI) mismatch model in hemispheric stroke less than 9 hours.Methods one-stop shop CT examination including non-contrast enhanced CT (NCCT), CTP, CT angiography (CTA) were performed in 24 patients with symptoms of stroke less than 9 hours.The Alberta Stroke Program Early CT Score (ASPECTS) were analyzed on arterial phase CTP-SI and venous phase CTP SI using Wilcoxon rank-sum test, then compared with the follow up imaging ASPECTS using multiple linear regression.Results The median (min-max) scores of ASPECTS on arterial phase CTP-SI, venous phase CTP-SI and follow-up imaging were 9.0 ( 2.0-10.0 ), 9.3 ( 6.5-10.0 ) and 9.0 ( 7.0-10.0 ),respectively. ASPECTS measured on arterial phase CTP-SI significantly differed from the ASPECTS on venous phase CTP-SI ( Z =-2.812, P = 0.005 ).Moreover, the linear regression analysis showed significant correlation between the ASPECTS on venous phase CTP-SI and follow up imaging ASPECTS ( Beta =0.715,P = 0.003 ).Conclusion CTP-SI mismatch model provides a method of choice in predicting penumbra and infarct core in hemispheric stroke. Key words: Cerebrovascular accident; Tomography,X-ray computed; Perfusion

Is the KUB radiograph redundant for investigating acute ureteric colic in the non-contrast enhanced computed tomography era?

To establish whether non-contrast enhanced computed tomography (NCCT) renders the kidneys-ureters-bladder (KUB) radiograph redundant as the initial imaging investigation for suspected acute ureteric colic. The imaging investigations for 120 patients consecutively admitted to an emergency department-led clinical decisions unit (CDU) with suspected acute ureteric colic were retrospectively reviewed. A multidisciplinary meeting reviewed the findings and recommended that KUB radiographs should not be routinely performed prior to NCCT. Prospective assessment of 116 consecutive patients admitted over a comparable period was then undertaken. In the retrospective group, 61 (50.8%) patients had calculi to account for symptoms (positive NCCT) and 59 (49.2%) patients did not have stone disease (negative NCCT). Ninety (75%) patients had a KUB radiograph prior to NCCT. However, in 46 (38% of total) of these patients the NCCT was negative for stones, and therefore, they had been subjected to an unnecessary radiographic examination. These results prompted a change in practice. In the subsequent and prospectively studied group, preliminary KUB radiographs were performed in only 6% of the patients, with no significant change in the positive NCCT rate (50.8 versus 51.7%) or the total number of examinations performed (120 versus 116). NCCT should be the initial imaging examination for acute ureteric colic. Up to 50% of patients with clinical suspicion do not have stone disease, and therefore, preliminary KUB radiographs with attendant radiation and cost implications are unjustified. Preliminary KUB radiographs can be omitted from the imaging pathway with no resultant indication creep or increase in demand for NCCT examinations.

Preoperative Radiographic Assessment of Hepatic Steatosis with Histologic Correlation

The adverse impact of hepatic steatosis on perioperative outcomes after liver resection is gaining recognition. But the accuracy of preoperative radiologic assessment of fatty liver disease remains unclear. The objective of this study was to correlate preoperative radiologic estimation with postoperative histologic measurement of steatosis. Patients who underwent partial hepatectomy between 1997 and 2001, with complete preoperative radiographic imaging and postoperative pathologic assessment of steatosis, were retrospectively analyzed. The presence of steatosis was assessed radiographically using noncontrast-enhanced CT (NCCT), contrast-enhanced CT (CCT), or MRI, using standard quantitative radiologic criteria. Repeat histologic analysis was used to quantify the extent of hepatic steatosis. One hundred thirty-one patients were studied. The overall sensitivity and specificity for all imaging modalities in detecting pathologically confirmed hepatic steatosis were 56% and 82%, respectively. Sensitivity and specificity for NCCT, CCT, and MRI using standard quantitative criteria were 33% and 100%, 50% and 83%, and 88%, and 63%, respectively. Increasing body mass indices adversely affected the accuracy of NCCT (p=0.002). Preoperative chemotherapy did not notably affect radiologic accuracy. The presence of a fatty-appearing liver on NCCT scans indicates clinically significant steatosis, but steatosis cannot be excluded based on a normal NCCT scan, particularly in obese patients. Conversely, normal MRI helps to exclude hepatic steatosis, but abnormal MRI is not a reliable indicator of fatty change. CCT is not an effective means of identifying steatosis. We conclude that, when used alone, conventional cross-sectional imaging does not consistently permit accurate identification of hepatic steatosis.

Focused Helical CT Using Rectal Contrast Material Only as the Preferred Technique for the Diagnosis of Suspected Acute Appendicitis: A Prospective, Randomized, Controlled Study Comparing Three Different Techniques

Focused helical CT using rectal contrast material only has emerged recently as an accurate diagnostic tool for the evaluation of suspected acute appendicitis. This study was designed to prospectively compare the efficacy of rectal contrast CT to other commonly used contrast-enhanced and nonenhanced CT techniques for the detection of acute appendicitis. A total of 232 patients with clinically suspected appendicitis were randomly assigned to one of three focused helical CT techniques: noncontrast enhanced CT, CT using rectal contrast material only, and dual-contrast CT using both oral and intravenous material. All scans were interpreted by the on-call residents and reported immediately to the surgeon. The sensitivity, specificity, predictive values, and overall accuracy rates were compared between the protocols. One hundred eleven patients (48 percent) had acute appendicitis. The sensitivity and specificity rates of rectal contrast CT were 93 and 95 percent, respectively, with overall accuracy of 94 percent. The sensitivity and specificity rates of dual-contrast CT were 100 and 89 percent, respectively, with overall accuracy of 94 percent. The sensitivity and specificity of noncontrast enhanced CT were 90 and 86 percent, respectively, but the overall accuracy was significantly lower (70 percent) compared with the other studies. Rectal contrast CT is as accurate, although less sensitive, compared with dual-contrast CT and significantly superior to noncontrast-enhanced CT for the diagnosis of acute appendicitis. Rectal contrast CT may be performed rapidly, saves resources, and may avoid the diagnostic delay and potential allergic reactions associated with oral and intravenous-enhanced studies, and, therefore, may be the preferred initial technique in the diagnostic workup of suspected acute appendicitis.

Multimodal Use of Computed Tomography in Early Acute Stroke, Part 2

Computed tomography (CT) scan remains the most widely technique in the cerebrovascular emergency, as it is largely available, minimally invasive, fast, cheap and reliable. Noncontrast enhanced CT (NeCT) imaging can show early signs of infarction in ischemic stroke; however, it could not show if the ischemic tissue is irreversibly damaged. CT perfusion (CTP) imaging has been shown to predict stroke location and size and can provide information about ischemic cerebral parenchyma not definitively compromised. CT angiography (CTA) could highlight stenosis or occlusion both in intracranial and extracranial vessels. By combining NeCT, CTP, and CTA the entire cerebrovascular axis can be imaged during acute stroke. Currently, the term “multimodal CT” indicates the combined use of these three techniques in order to obtain a complete picture of the extension of ischemic damage in acute stroke patients.

Shock wave lithotripsy success determined by skin-to-stone distance on computed tomography

Objectives To evaluate whether the skin-to-stone distance (SSD), body mass index (BMI), and Hounsfield unit (HU) density can be used as independent predictors of stone-free (SF) status after shock wave lithotripsy (SWL) of lower pole kidney stones. No studies have evaluated the SSD by non-contrast-enhanced computed tomography (NCCT) as a predictor of SWL success. Studies have suggested that the BMI and HU density of urinary calculi on NCCT may predict the SF rate after SWL. Methods The radiographs of 64 patients treated with SWL (DoliS lithotripter) from March 2000 to April 2004 with lower pole kidney stones measuring 0.5 to 1.5 cm on NCCT were reviewed. The average SSD was calculated by measuring three distances from the center of the stone to the skin (0°, 45°, and 90° angles) on NCCT. The BMI and HU density were determined, and chemical analysis was performed on all stones. Radiographic assessment of the kidneys, ureter, and bladder at 6 weeks categorized patients into the SF or residual stone group. Logistic regression was fit, using SSD, BMI, and HU density as predictors, to assess the SF rates after SWL. Results Of 64 patients, 30 were SF and 34 had residual stones. The mean SSD was 8.12 ± 1.74 cm for the SF group versus 11.53 ± 1.89 cm for the residual stone group ( P <0.01). Logistic regression analysis revealed only SSD to be a significant predictor of outcome (odds ratio 0.32, 95% confidence interval 0.29 to 0.35, P <0.01). An SSD greater than 10 cm predicted treatment failure. Conclusions The SSD may predict the outcome after SWL of lower pole kidney stones. SWL in patients with an SSD greater than 10 cm is likely to fail. The use of the SSD may be transferable to the treatment of all urinary stones, regardless of location.

Investigation of Acute Flank Pain: How Do Practices of U.K. and Irish Urologists Compare with Those of Transatlantic and Continental European Colleagues?

Noncontrast-enhanced spiral CT (NESCT) is more accurate and reliable than intravenous urography (IVU) in diagnosing the cause of acute flank pain. This study aimed to determine the impact of current literature on the choice of imaging modality used to investigate acute flank pain within the UK and the Republic of Ireland. A questionnaire regarding the preferred investigation for acute flank pain was sent to all consultant urologists registered as British Association of Urological Surgeons members. Of the 548 consultants from 210 institutions surveyed, 293 (54%) from 171 (81.4%) institutions returned their questionnaires. Intravenous urography is used in the majority of institutions (146; 85.4%) for investigating acute flank pain. Only 18 (10.5%) use NESCT, while 4.1% use ultrasonography. Among those using IVU as the investigation of choice, the main reason given was limited CT services (82.4%). Others included familiarity with IVU features (51.2%), limited availability of radiologists for out-of-hours reporting of CT (26%), more rapid procedure (20.8%), lower cost (20%), and lower radiation exposure (19.6%). Only 52.4% of consultants using IVU would prefer NESCT if both were equally available. Urography remains the commonest modality for the investigation of acute flank pain in the UK and Ireland primarily because of limited CT services and greater familiarity with the images. Given the opportunity, only half of consultant urologists would select NESCT in preference to IVU, suggesting that improving the availability of CT services alone may not lead to practice paralleling that of our transatlantic and continental European colleagues.

CT-Diagnostik bei akuter zerebraler Ischämie

The advent of new MRI techniques such as perfusion- (PWI) and diffusion- (DWI) weighted imaging has improved diagnostic imaging in stroke. However, CT scanners are more widely available and less expensive than MRI scanners and are often located in the emergency departments even of smaller community hospitals. Topic of this article is CT-based diagnosis of patients with hyperacute ischemic stroke. In hyperacute stroke, a multiparametric CT protocol allows a comprehensive diagnosis by combining non-contrast enhanced CT (NECT), perfusion CT (PCT), and CT angiography (CTA). PCT can render important information about the hypoperfused brain tissue, CTA provides further important information about the vessel status. When stroke MRI is not available, multiparametric stroke CT can give nearly equivalent information, and can help to identify patients for thrombolytic therapy.

Is intravenous urography a prerequisite for renal shockwave lithotripsy?

To determine whether intravenous urography (IVU) is a prerequisite for shockwave lithotripsy (SWL) of renal stones by addressing whether using non-contrast-enhanced CT (NCCT) instead of IVU for delineating urinary tract anatomy is associated with post-SWL complications. Thirty-eight patients treated by SWL (Econolith 2000) for radiopaque renal stones underwent either IVU or NCCT. Twenty patients with normal urinary tracts or with mild hydronephrosis proximal to the stone on urography comprised the IVU group. Eighteen patients who underwent NCCT and plain abdominal (KUB) films and had urinary tract systems similar in appearance to the IVU group comprised the NCCT group. The two groups were of similar mean age (45.75 years, range 24-73 years; and 49.0 years, range 26-72 years, respectively) and had a similar mean stone size (10.1-10.2 mm). Patients with internal ureteral or nephrostomy catheters were excluded. Information on episodes of intractable renal colic, urinary tract infections, and hospitalization was recorded at follow-up 2 to 6 weeks post-SWL. The IVU and NCCT patients had similar mean stone fragmentation rates (80% and 74%, respectively) at 2 to 6 weeks post-SWL. Four IVU patients (20%) had intractable renal colic. One NCCT patient (5.5%) had a urinary infection. Complication and hospitalization rates in the two groups were not significantly different (P = 0.34; Fisher' exact test). Using only NCCT before SWL was not associated with higher complication rates. Thus, IVU is not a prerequisite for SWL of radiopaque renal stones in patients with a normal urinary tract anatomy as seen on NCCT.

Computed tomography and ultrasonography of acute renal abnormalities.

MAGING OF the kidneys may be necessary for the evaluation of a variety of urgent clinical indications including flank pain, gross hematuria, rising serum creatinine, blunt abdominal trauma, and suspected upper urinary tract infection. In this setting, sonography and computed tomography (CT) are the two most widely used imaging modalities. The advantages of sonography include that it is generally widely available, it is portable, and it is relatively inexpensive. Although sonography is highly accurate for the detection of hydronephrosis and renal calculi, there are a number of limitations with this modality. Generally, the kidney, renal pelvis, and urinary bladder can be readily visualized by sonography; however, most, if not all, of the ureter is typically obscured by overlying structures, Sonography is also limited by its relatively low soft-tissue contrast such that processes that cause only a minimal change in the appearance of the parenchyma, such as pyelonephritis, are often not detected. Additionally, sonography provides only anatomic information and cannot assess renal function. CT requires the use of intravenous iodinated contrast material to assess the renal parenchyma, but offers the ability to assess both structure and function and is capable of examining the entire urinary tract. Contrast-enhanced CT is able to detect subtle changes in the enhancement pattern of the kidneys leading to a more accurate diagnosis of inflammatory processes affecting the kidney and urinary tract. Following abdominal trauma, contrast-enhanced CT offers the ability to stage the full extent of parenchymal injury, assess the integrity of collecting system and vascular pedicle, and to assess for concomitant injuries to other abdominal organs. Noncontrastenhanced CT has emerged as an accurate examination for the detection and characterization of obstructing renal and ureteral calculi. Therefore, CT has become the imaging modality of choice in many institutions for the evaluation of suspected renal colic, upper tract inflammatory disease and in the setting of acute trauma.

Primary Leptomeningeal Malignant Melanoma in Posterior Fossa and Upper Cervical Canal: A Case Report

The term ‘primary melanocytic neoplasm’covers a wide disease spectrum, from well differentiated meningeal melanocytoma to malignant melanoma, its most aggressive malignant counterpart. Previous reports have shown that due to the paramagnetic effect of melanin, melanocytic neoplasms show high signal intensity on T1-weighted images and very low signal intensity on T2-weighted images, with relatively homogeneous contrast enhancement. The differentiation of leptomeningeal malignant melanoma from benign melanocytoma is important because of their different prognosis but on the basis of imaging findings alone is difficult. Ultrastructural immunohistochemical analysis is a possible alternative. We report the imaging findings of rare primary malignant melanoma, revealed by noncontrast-enhanced CT as a high-density mass, and demonstrating high signal intensity on T1-weighted images, and very low signal intensity on T2WI, with relatively good contrast enhancement.

Helical CT scanning: The primary imaging modality for acute flank pain

We set out to evaluate the accuracy of nonenhanced helical computed tomography (CT) scanning at stone detection in the patient with acute flank pain, and as a means of detecting noncalculus causes of acute flank pain. Between April 1995 and April 1997, 412 consecutive patients with acute flank pain underwent noncontrast-enhanced helical CT. Two hundred eighty-one patients had confirmation of their CT diagnosis by other radiographic studies, urologic intervention, or spontaneous stone passage of calculi. We determined the presence or absence of urinary calculi, as well as the presence of other noncalculus pathology. CT scanning revealed a stone in 92/281 patients (32.7%) and no stone in 189/281 patients (67.3%). Of the 189 patients, 60/189 patients (32%) had another positive finding as a cause for flank pain. Eighty-one of 92 patients with a stone on CT (88%) had confirmation of stone disease by radiologic or surgical intervention. Eleven of 92 patients (12%) did not have confirmation of their diagnosis because of resolution of symptoms or refusal of further intervention. On helical CT scans 129/189 patients demonstrated no abnormalities. Two of 189 (1.5%) thought to be stone free by CT passed a stone. Helical CT had a sensitivity of 97%, a specificity of 92%, a positive predictive value of 88%, and a negative predictive value of 98% at stone detection. Noncontrast-enhanced helical CT is accurate and rapid in detecting calculus disease in patients with acute flank pain. Perhaps more importantly, it provides the added benefit of detecting noncalculus causes of flank pain in greater than 30% of patients. (Am J Emerg Med 2000;18:649-652.