Patients with acute flank pain: comparison of MR urography with unenhanced helical CT

PURPOSE: To compare unenhanced helical computed tomography (CT) and magnetic resonance (MR) urography, by using T2-weighted and contrast material-enhanced T1-weighted imaging to examine patients with acute flank pain, with reference to excretory urography and final clinical diagnosis. MATERIALS AND METHODS: Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine-enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results. RESULTS: At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P <.001) and 0.75 (P <.001) and at MR urography, 0.49 (P =.005) and 0.51 (P =.004). CONCLUSION: In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.     

CT urography and MR urography

CT urography and MR urography are an evolving concept and developing technique. As the technology matures, CT urography will combine the ultimate diagnostic capabilities of intravenous urography and CT. In the near future, many intravenous urograms will be replaced by CT urography to evaluate patients with hematuria and other genitourinary conditions. MR urography currently serves as an alternative imaging technique to intravenous urography and CT urography for children and pregnant women and for patients with contraindications to iodinated contrast media.     

Breathhold MR urography: comparison between HASTE and RARE in healthy volunteers

The purpose of our study was to determine relative values of rapid acquisition relaxation enhancement (RARE) and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences in breathhold magnetic resonance (MR) urography in healthy volunteers under nonobstructive conditions of the urinary tract. A total of 20 healthy volunteers underwent MR urography with breathhold RARE and HASTE sequences at 1.5 T. For evaluation, the urinary tract was divided into nine segments on each side. Visualization of segments and artifacts was scored and the intensity ratios (InR) were determined. The upper five urinary segments were sufficiently visualized with RARE and significantly better with HASTE (renal calices, p = 0.002–0.037). The middle and lower ureter was sufficiently delineated both with RARE and HASTE, but HASTE images were statistically superior (p = 0.009–0.041). Both in RARE and HASTE images, the lower ureter was frequently superimposed by bowel contents and bowel motion. Superimposition of genital organs degraded image quality in eight of ten female volunteers. InRs were superior with HASTE in the kidney and ureter (p = 0.0003–0.0125). RARE InRs were higher in the bladder (p = 0.0008–0.014). We concluded that neither the RARE nor the HASTE sequences allowed the evaluation of the entire urinary tract under nonobstructive conditions. Although it cannot entirely replace intravenous urography, MR urography seems to lend itself to combination with other MR techniques, particularly in the investigation of pelvic or retroperitoneal disease. Received 28 October 1996; Revision received 7 November 1997; Accepted 29 December 1997     

MSCTA和MSCTU对肾盂输尿管连接部梗阻的诊断价值

目的：探讨MSCT血管成像（MSCTA）及尿路成像（MSCTU）在肾盂输尿管连接部梗阻（UPJO）诊断中的价值。方法：回顾性分析经手术病理证实的16例UPJO患者的MSCTA及MSCTU影像资料,利用多种后处理重组技术（MPR、CPR、MIP、VR）进行重组。结果：16例肾盂输尿管连接部梗阻中,梗阻位置全部诊断正确。梗阻原因诊断为输尿管息肉1例,血管压迫3例,炎性狭窄12例。术前诊断与手术探查及病理结果基本一致。结论：MSCTU和MSCTA可作为UPJO术前评估的常规方法,在诊断引起UPJO的疾病方面具有重要价值。     

Internal derangement of the wrist: indirect MR arthrography versus unenhanced MR imaging

PURPOSE: To compare indirect magnetic resonance (MR) arthrography with unenhanced MR imaging of the wrist for evaluation of the central disk of the triangular fibrocartilage complex (TFCC) and the scapholunate and lunotriquetral interosseous ligaments. MATERIALS AND METHODS: Eighty-six wrists were evaluated at MR imaging (41 indirect MR arthrography and 45 unenhanced MR imaging examinations). Three musculoskeletal radiologists independently evaluated the central disk of the TFCC and scapholunate and lunotriquetral ligaments and compared the results with those of wrist arthroscopy. Sensitivity and specificity were calculated for each of the readers, and the means were obtained. Sensitivities and specificities were compared with the Student t test. RESULTS: Thirty-three tears of the central disk of the TFCC and 13 scapholunate and 18 lunotriquetral ligament tears were identified at arthroscopy. Sensitivities and specificities were 54%-73% and 83%-91%, respectively, in the evaluation of the central disk of the TFCC, with no significant difference between indirect MR arthrography (P =.666) and unenhanced MR imaging (P =.559). Sensitivities and specificities in the evaluation of the scapholunate ligament were 38%-69% and 75%-99%, respectively, with a significant improvement in sensitivity at indirect MR arthrography (P =.017) and no significant difference in specificity (P =.876). Sensitivities in the evaluation of the lunotriquetral ligament were poor, 0%-22%, though the specificities were 88%-99%, with no significant difference between indirect MR arthrography and unenhanced MR imaging (P =.592 and P =.354, respectively, for sensitivity and specificity. CONCLUSION: Indirect MR arthrography significantly improves sensitivity in the evaluation of the scapholunate ligament when compared with unenhanced MR imaging of the wrist but does not significantly improve the ability to evaluate the central disk of the TFCC or the lunotriquetral ligament.     

Liver and abdominal screening in patients with cancer: CT versus MR imaging

A prospective multiinstitutional study was performed to compare the ability of dynamic sequential contrast material-enhanced computed tomography (CT), delayed contrast material-enhanced CT, and two T1-weighted magnetic resonance (MR) sequences (spin echo and inversion recovery) to demonstrate metastatic disease in the liver and abdomen in patients with cancer. All four techniques had comparable rates of hepatic lesion detection when compared individually or when the combined CT techniques were compared with the combined MR techniques. The sensitivity to hepatic disease was 96% (27 of 28 patients) for the combined MR techniques versus 93% (26 of 28 patients) for the combined CT techniques. However, CT was statistically superior in the detection of extrahepatic disease, with significant extrahepatic findings demonstrated by CT in only 12 of 59 patients (20%). For this reason, the authors continue to recommend CT in the initial screening of patients with cancer for upper abdominal metastatic disease.     

Acute experimental osteomyelitis and abscesses: detection with MR imaging versus CT

Acute experimental osteomyelitis and abscesses were induced in the proximal tibia and surrounding soft tissues, respectively, in 67 New Zealand white rabbits. Fifty-three rabbits were injected with a Staphylococcus aureus solution and 26, with sterile saline in tibial medullae and/or surrounding soft tissues. Contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging were performed 7 days after inoculation. Immediately after imaging, the animals were killed and necropsy was performed. MR imaging was more sensitive than CT in the detection of osteomyelitis (94% vs 66%, P less than .025) and abscesses (97% vs 52%, P less than .001). MR imaging was equally specific as CT in the exclusion of osteomyelitis (93% vs 97%, chi 2 = 0) but less specific than CT in the exclusion of abscesses (77% vs 100%, P less than .025). The overall accuracy of MR imaging was somewhat, although not significantly, greater than that of CT in the detection of both osteomyelitis (93% vs 80%) and abscesses (87% vs 75%).     

Conspicuity of renal calculi at unenhanced CT: effects of calculus composition and size and CT technique

PURPOSE: To determine the effects of calculus size, composition, and technique (kilovolt and milliampere settings) on the conspicuity of renal calculi at unenhanced helical computed tomography (CT). MATERIALS AND METHODS: The authors performed unenhanced CT of a phantom containing 188 renal calculi of varying size and chemical composition (brushite, cystine, struvite, weddellite, whewellite, and uric acid) at 24 combinations of four kilovolt (80-140 kV) and six milliampere (200-300 mA) levels. Two radiologists, who were unaware of the location and number of calculi, reviewed the CT images and recorded where stones were detected. These observations were compared with the known positions of calculi to generate true-positive and false-positive rates. Logistic regression analysis was performed to investigate the effects of stone size, composition, and technique and to generate probability estimates of detection. Interobserver agreement was estimated with kappa statistics. RESULTS: Interobserver agreement was high: the mean kappa value for the two observers was 0.86. The conspicuity of stone fragments increased with increasing kilovolt and milliampere levels for all stone types. At the highest settings (140 kV and 300 mA), the detection threshold size (ie, the size of calculus that had a 50% probability of being detected) ranged from 0.81 mm + 0.03 (weddellite) to 1.3 mm + 0.1 (uric acid). Detection threshold size for each type of calculus increased up to 1.17-fold at lower kilovolt settings and up to 1.08-fold at lower milliampere settings. CONCLUSION: The conspicuity of small renal calculi at CT increases with higher kilovolt and milliampere settings, with higher kilovolts being particularly important. Small uric acid calculi may be imperceptible, even with maximal CT technique.     

Radiologic investigation of renal colic: unenhanced helical CT compared with excretory urography.

OBJECTIVE: Our aim was to compare unenhanced helical CT and excretory urography in the assessment of patients with renal colic. SUBJECTS AND METHODS: Fifty-three of 70 consecutive patients with acute signs of renal colic were prospectively examined with unenhanced helical CT, which was followed immediately by excretory urography. Two radiologists who were unaware of the findings independently interpreted these examinations to determine the presence or absence of ureteral obstruction. On all CT scans that had positive findings for ureteral stones or obstruction, we looked for secondary signs of obstruction (perinephric or periureteral fat stranding, ureteral wall edema, ureteral dilatation, and blurring of renal sinus fat). RESULTS: A stone was recovered in 45 of the 53 patients, nine before and 36 after imaging. The latter 36 patients had their stones identified on CT, whereas only 24 patients had their stones identified on excretory urography. Eight patients without stone disease had normal ureters on both CT and excretory urography. Of the 45 patients who had stone disease, 26 had ureteral dilatation on both CT and excretory urography, and 36 patients who recovered a stone after CT had secondary signs of obstruction. Of the nine patients who recovered a stone before CT, three had secondary signs of obstruction. Two patients had periureteral fat stranding, ureteral wall edema, and renal sinus fat blurring. One patient had only ureteral wall edema. CONCLUSION: Compared with excretory urography, unenhanced helical CT is better for identifying ureteral stones in patients with acute ureterolithiasis. Secondary CT signs of obstruction, including renal sinus fat blurring, were frequently present even when the stone was eliminated before imaging.     

尿路梗阻磁共振水成像技术与IVU及CT检查对照研究

磁共振尿路成像(MR)是国外近年开展的一项泌尿系影像学检查新方法.现将我院MR检查与CT及IVU检查结果对比如下.     

Detection of brain metastases: comparison of contrast-enhanced MR with unenhanced MR and enhanced CT

Contrast-enhanced MR studies were compared with noncontrast MR and contrast-enhanced CT scans in the evaluation of intraparenchymal brain metastases. Fifty consecutive inpatients were studied with short and long repetition time (TR) sequences before and after the administration of gadopentetate dimeglumine. In addition, a delayed short TR sequence was performed. The contrast CT, noncontrast MR, immediate postcontrast short TR sequence, postcontrast long TR sequence, and delayed postcontrast short TR sequence were each read blindly and independently by two neuroradiologists. These results were then compared with a final interpretation, reached by all the neuroradiologists in the study, using all the clinical information and imaging findings. Postcontrast short TR scans proved to be superior to other sequences. They were particularly useful in the detection of metastases in the posterior fossa and cortex. The delayed postcontrast short TR scan held no definite advantage over the immediate postcontrast short TR scan, although metastases were sometimes seen slightly better after the delay. While long TR sequences were not always sensitive or specific, they often did provide ancillary information and were particularly useful in cases of hemorrhagic metastases. Because of these findings, we recommend that the evaluation of intraparenchymal metastases consist of a single postcontrast long TR scan followed by a single postcontrast short TR scan. While these sequences should be very accurate in the detection of metastases, we also generally perform a single precontrast short TR scan as well, since the question of hemorrhage or bone lesion may be clinically relevant.     

多层螺旋CT泌尿系统造影对小儿上尿路梗阻病变诊断及应用价值

上尿路梗阻是小儿泌尿系统常见的一组疾病,主要依靠影像检查,MSCTU是一种无创伤检查,操作简便,能可靠地显示泌尿系统立体结构的方法,是螺旋CT容积扫描与IVP有机的结合,在小儿上尿路梗阻疾病诊断中具有明显的优势。     

Acute myocardial infarction: assessment of left ventricular function with 16-detector row spiral CT versus MR imaging--study in pigs

PURPOSE: To assess global left ventricular (LV) function and regional wall motion with retrospective electrocardiographically gated 16-detector row computed tomography (CT) in comparison with magnetic resonance (MR) imaging. MATERIALS AND METHODS: In 15 pigs (mean weight, 53.9 kg +/- 9.5 [standard deviation]), acute myocardial infarction was induced with balloon occlusion of the left anterior descending coronary artery after approval was obtained from the committee on animal affairs. Thereafter, multi-detector row CT and MR imaging were performed with standardized examination protocols. From manually drawn endocardial and epicardial contours, LV volumes, including mean ejection fraction, peak filling rate (PFR), peak ejection rate (PER), time to PER, and time from end systole to PFR, were calculated. Regional wall motion was assessed from cine loops with a 16-segment model of the left ventricle. LV function was analyzed by using Bland-Altman plots, Student t test, and Pearson correlation coefficient. Regional wall motion scores were compared with weighted kappa statistic. RESULTS: LV volumes determined with multi-detector row CT correlated well with MR imaging results, with an ejection fraction of 46.1% +/- 6.5 for multi-detector row CT and 46.8% +/- 5.9 for MR imaging (r = 0.97). PER, PFR, time to PER, and time from end systole to PFR showed a wide range of scattering and significant differences between multi-detector row CT and MR imaging for PER and time from end systole to PFR (P < .05). Regional wall motion scores showed a very high level of agreement with a kappa value of 0.88. CONCLUSION: Although 16-detector row CT allows reliable assessment of LV volumes and regional wall motion at rest, it is not suited for assessment of all functional parameters.     

Nontraumatic acute abdominal pain: unenhanced helical CT compared with three-view acute abdominal series

PURPOSE: To prospectively evaluate and compare the diagnostic accuracy of unenhanced helical computed tomography (CT) for patients with nontraumatic acute abdominal pain with that of traditional abdominal radiography. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained; this study was completed before implementation of the HIPAA. Ninety-one patients (44 men; 47 women; age range, 18-84 years; mean age, 48.5 years) with acute nontraumatic abdominal pain over a 7-month period were referred by the emergency department of one institution. These patients underwent a three-view acute abdominal series (AAS) and unenhanced helical CT. AAS included an upright chest radiograph and upright and supine abdominal radiographs. Unenhanced helical CT images with 5-mm collimation were obtained from the lung bases to the pubic symphysis, without intravenous, oral, or rectal contrast material. AAS and unenhanced helical CT images were each separately and prospectively interpreted by a different experienced radiologist who was blinded to patient history and the images and interpretation of the other examination for each patient. Final diagnosis was established with surgical, pathologic, and clinical follow-up. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and positive and negative likelihood ratios were calculated for AAS and unenhanced helical CT. Confidence intervals of 95% were calculated for each value with the standard equation for population proportions. Results of AAS and unenhanced helical CT examinations were compared with chi2 analysis. RESULTS: Among the 91 patients examined, unenhanced helical CT yielded an overall sensitivity, specificity, and accuracy of 96.0%, 95.1%, and 95.6%, respectively. The AAS interpretations yielded an overall sensitivity, specificity, and accuracy of 30.0%, 87.8%, and 56.0%, respectively. The accuracy of unenhanced helical CT was significantly greater than the accuracy of AAS (P < .05). CONCLUSION: AAS is an insensitive technique in the evaluation of nontraumatic acute abdominal pain in adults. Unenhanced helical CT is an accurate technique in the evaluation of adult patients with nontraumatic acute abdominal pain and should be considered as an alternative to radiography as the initial imaging modality.     

值得注意的急性肺动脉栓塞平扫CT征象

目的描述能提示急性肺动脉栓塞的CT平扫征象。方法回顾性分析49例经临床治疗证实的急性肺动脉栓塞病例的螺旋CT影像，发现能提示急性肺动脉栓塞的平扫异常征象。结果在49例平扫影像中，共有10例出现肺动脉密度改变，其中局限性密度增高6例，局限性密度减低4例。结论急性肺动脉栓塞的确诊需要行CT增强扫描，但对于不能使用对比剂或因非典型心肺症状而仅作平扫的病例，肺动脉CT平扫的异常密度改变能提示急性肺动脉栓塞的存在。     

螺旋CT及尿路造影对肾积水疾病的诊断价值

肾积水的原因很多，B超、腹部平片和静脉尿路造影对此诊断很有限。随着多排螺旋CT技术的不断改进和发展，CT尿路造影（computed tomography urography，CTU）价值远远优于以上检查手段，已被广泛应用于泌尿系检查和临床诊断。