Prospective comparative study of negative oral contrast agents for magnetic resonance cholangiopancreatography.

PURPOSE: The aim of this study was to compare prospectively the image quality of magnetic resonance cholangiopancreatography (MRCP) using manganese chloride tetrahydrate (Bothdel Oral Solution 10) (MCT), a new negative oral contrast agent; ferric ammonium citrate (FerriSeltz powder 20%) (FAC); and no agent. MATERIALS AND METHODS: MRCP images (TE 970 ms) of patients administered MCT (n = 19) or FAC (n = 20) at random, and 18 patients without an agent were evaluated. The subjective image quality of the overall, extrahepatic bile duct, and pancreatic duct and the degree of elimination of gastrointestinal fluid scored by two radiologists blinded to information regarding the agent were compared using Mann-Whitney's U-test. RESULTS: The degrees of elimination of gastroduodenal fluid of MCT and FAC were significantly better than those without an agent (P < 0.01 and P < 0.01). The subjective image quality of MCT of the overall and extrahepatic bile duct were significantly better, although no significant differences for FAC were observed compared with those without an agent (P < 0.01 and P = 0.21, P = 0.02 and P = 0.16). There were no significant differences for the pancreatic duct (P = 0.12 and P = 0.19), nor were there any significant differences in the evaluations between MCT and FAC (P = 0.19-0.98). CONCLUSION: MCT has shown performance comparable to that of conventional FAC in terms of pancreatic and biliary depiction and safety.

Hyperattenuating signs at unenhanced CT indicating acute vascular disease.

When a vascular disease is suspected, the focus is usually on morphologic features seen at contrast material-enhanced multidetector computed tomography (CT). However, unenhanced CT also plays an important role in revealing so-called hyperattenuating signs, which represent a slight increase in the focal attenuation of a vessel. Hyperattenuating signs are occasionally observed when an acute clot has formed in a vessel and can be seen in various vascular diseases, including acute arterial occlusion, acute arterial dissection, aneurysm rupture, and acute venous thrombosis. The attenuation of these signs tends to increase because the concentration of hemoglobin increases as water content decreases. Hyperattenuating signs are a transient phenomenon, as the attenuation gradually decreases. Therefore, they can serve as unique findings indicating an acute state. Although hyperattenuating signs are not well understood, recognition of these signs is important because they can help reveal serious acute vascular diseases even at unenhanced CT.

Defining juxtapapillary diverticulum with 3D segmented trueFISP MRCP: comparison with conventional MRCP sequences with an oral negative contrast agent.

PURPOSE: To compare three-dimensional segmented true fast imaging with steady-state precession magnetic resonance cholangiopancreatography (3D-trueFISP-MRCP) to conventional MRCP sequences with an oral negative contrast agent for diagnosing juxtapapillary diverticulum. MATERIALS AND METHODS: A total of 42 patients with (n = 21) and without (n = 21) juxtapapillary diverticulum confirmed by endoscopic retrograde cholangiopancreatography (ERCP) were evaluated. Three MRCP sequences, 3D-trueFISP-MRCP, two-dimensional rapid acquisition with relaxation enhancement MRCP (2D-RARE-MRCP), and 3D T(2)-weighted turbo spin-echo MRCP (3D-TSE-MRCP), obtained after administering an oral negative contrast agent (FerriSeltz; Otsuka Pharmaceutical, Tokushima, Japan) were compared. Two radiologists independently and blindly interpreted the presence or absence of juxtapapillary diverticulum and its positional relationship against the papilla. The detectability of juxtapapillary diverticulum of each sequence as decided by consensus was then compared. Kappa statistics were used to measure interobserver agreement of the classifications. RESULTS: The sensitivity, specificity, and accuracy for detecting juxtapapillary diverticulum of 3D-trueFISPMRCP (61.9%, 85.7%, and 73.8%) were substantively higher than those of 2D-RARE-MRCP (0.0%, 100%, and 50.0%) and 3D-TSE-MRCP (9.5%, 100%, and 54.8%). Interobserver agreement of the position of juxtapapillary diverticulum by 3D-trueFISP-MRCP was good (kappa = 0.55). CONCLUSION: 3D-trueFISP-MRCP can define juxtapapillary diverticulum even with an oral negative contrast agent, whereas conventional MRCP sequences cannot.

Comparison of SPACE and 3D TSE MRCP at 1.5T focusing on difference in echo spacing.

PURPOSE: We compared the image quality of SPACE (sampling perfection with application optimized contrasts using different flip angle evolutions) and conventional 3D turbo spin echo (TSE) magnetic resonance cholangiopancreatography (MRCP) at 1.5 tesla with regard to difference in echo spacing. METHODS: Twenty healthy volunteers prospectively underwent navigator-triggered SPACE and 3D TSE MRCP at 1.5T with identical parameters, except for echo spacing. Quantitative analyses of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), relative contrast, and contour sharpness index of each segment of the pancreaticobiliary tree were compared using paired t-tests. Qualitative analyses on a 5-point scale (1, excellent; 5, poor) scored by 2 independent radiologists were compared using Wilcoxon signed-rank test. RESULTS: The SNR, CNR, and contour sharpness index of each segment were significantly better for the SPACE sequence than 3D TSE (P < 0.05). Relative contrast and subjective image quality were not significantly different (P > 0.05). CONCLUSION: We verified SPACE MRCP quantitatively superior to conventional 3D TSE MRCP at 1.5T as a result of shortening of echo spacing.

Feasibility of diffusion-weighted MRI for defining placental invasion.

The purpose of this clinical note is to describe the feasibility of using diffusion-weighted imaging for diagnosing placental invasion with a case of placenta increta and six cases without it. Diffusion-weighted imaging (DWI) at a b-value of 1000 sec/mm(2) can clearly define the border between the placenta and myometrium because only the placenta shows very high signal intensity. The corresponding image at a b-value of 0 sec/mm(2) shows the myometrium with high signal intensity compared with the surrounding fat. Therefore, fusion of the two images can be used additionally to visualize thickness of the myometrium. As a result, DWI can be used to visualize the focal thinning of the myometrium caused by placenta increta, which has been difficult to diagnose on conventional magnetic resonance imaging sequences without contrast enhancement. However, the use of DWI for placental invasion should be determined following careful consideration of its risks and benefits, as fetus safety has not been established.

Navigator-triggered prospective acquisition correction (PACE) technique vs. conventional respiratory-triggered technique for free-breathing 3D MRCP: an initial prospective comparative study using healthy volunteers.

PURPOSE: To confirm the superiority of the navigator-triggered prospective acquisition correction (PACE) technique over the conventional respiratory-triggered (RESP) technique, something that has been perceived experimentally but without definite evidence, for free-breathing three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP) using healthy volunteers. MATERIALS AND METHODS: Free-breathing 3D turbo spin-echo MRCP using both PACE and RESP techniques were prospectively performed on 25 healthy volunteers. Quantitative analyses of acquisition time, signal-to-noise ratio, contrast-to-noise ratio, and contour sharpness index of each segment of the pancreaticobiliary tree were compared using the paired t-test. Qualitative analyses on a five-point scale (1, excellent; 5, poor) scored by two independent radiologists were compared using the Wilcoxon signed-rank test. RESULTS: The subjective image quality and contour sharpness index of each segment of the PACE technique were found to be significantly better than those for RESP (P<0.05). No significant difference was observed with regard to signal-to-noise and contrast-to-noise ratios except for the pancreatic duct. No significant difference in acquisition times between PACE and RESP techniques was observed. CONCLUSION: We confirmed the superiority of the image quality of the PACE technique compared to conventional RESP technique for free-breathing 3D MRCP in healthy volunteers.

Unruptured pseudoaneurysm of the cystic artery with acute calculous cholecystitis incidentally detected by computed tomography.

Pseudoaneurysm of the cystic artery is rare; to our knowledge, fewer than 30 cases have been reported worldwide. We report the first case of an unruptured pseudoaneurysm of the cystic artery with concurrent acute calculous cholecystitis. We incidentally detected the aneurysm by contrast-enhanced computed tomography (CT) in the edematous, thickened wall of the gallbladder neck in a 71-year-old man, whereas in most of the reported cases the disease presented as hemobilia. Because of the high risk of aneurysm rupture in this location, we avoided such interventions as percutaneous cholecystostomy and laparoscopic cholecystectomy. The aneurysm was localized pathologically in the undisrupted gallbladder wall, and elective open cholecystectomy with ligation of the cystic artery was performed successfully. Our case highlights the usefulness of CT for both diagnosis and patient management. Open cholecystectomy with ligation of the cystic artery is demonstrated as a reasonable first line of treatment for this unusual condition.

Compression belt for navigator-triggered trueFISP whole-heart coronary magnetic resonance angiography: study in healthy volunteers.

PURPOSE: To evaluate in healthy volunteers the usefulness of an abdominal compression belt in reducing acquisition time by stabilizing respiratory motion during whole-heart coronary magnetic resonance angiography (WHCMRA) using conventional navigator triggering. METHODS: In 10 healthy volunteers, we performed free-breathing 3-dimensional segmented true fast imaging with steady-state precession (trueFISP) WHCMRA using conventional navigator triggering without motion-adapted gating. We acquired images with the abdominal compression belt rolled tightly around the upper abdomen and without the belt. We compared image acquisition time, navigator efficiency, and visible length of coronary arteries using paired t-test and subjective image quality on a 4-point scale (1, poor; 4, excellent) using Wilcoxon signed-rank test. RESULTS: There were no statistically significant differences for mean acquisition time (11.5+/-5.0 vs. 9.3+/-2.4 min, P=0.150); navigator efficiency (38.7+/-13.6 vs. 42.8+/-11.0%, P=0.336); mean overall visible length of the coronary arteries (99.7+/-22.7 vs. 105.0+/-16.5 mm, P=0.530); or mean overall subjective image quality (2.5 vs. 2.7, P=0.297) between results obtained with and without the abdominal compression belt. CONCLUSION: In this small group of healthy volunteers, the use of an abdominal compression belt did not reduce image acquisition time or improve image quality in trueFISP WHCMRA using conventional navigator triggering; however, the technique's feasibility requires additional consideration using other navigator-triggering methods for patients with irregular respiratory cycles.

Stent-graft to treat intrahepatic portosystemic venous shunt causing encephalopathy.

Spontaneous intrahepatic portosystemic venous shunts (IPSVS) are rare, and angiographic intervention to treat IPSVS has been limited. To our knowledge, we present the first case of an IPSVS between the right portal vein and inferior vena cava accompanied by intractable encephalopathy that was successfully obliterated using a stent-graft deployed in the inferior vena cava to disconnect the portal and systemic venous circulation. Our patient, a 58-year-old woman, has shown no evidence of recurrent portosystemic venous shunt or encephalopathy for 30 months. We believe this intervention to be a useful alternative therapy for this type of shunt.

Prospective trial of a navigator setting under left hepatic lobe on magnetic resonance cholangiopancreatography using a free-breathing prospective acquisition correction technique.

PURPOSE: To prospectively compare the image acquisition time and image quality obtained by navigator setting under the left hepatic lobe vs. on the right diaphragm on magnetic resonance cholangiopancreatography (MRCP) using a free-breathing navigator-triggered prospective acquisition correction technique (PACE). MATERIALS AND METHODS: Fifty consecutive patients prospectively underwent three-dimensional T2-weighted turbo spin-echo MRCP using PACE with the navigator randomly set either under the left hepatic lobe or on top of the right diaphragm. Image acquisition time and subjective image quality were compared on a five-point scale using Student's t-test and Mann-Whitney's U test, respectively. RESULTS: There was no significant difference for mean acquisition time (6.1+/-1.6 vs. 6.3+/-1.2 min, P=.689) between the left hepatic lobe group and right diaphragm group. Mean subjective image quality was significantly worse in the left hepatic lobe group than in the right diaphragm group (4.1 vs. 4.7, P=.044). CONCLUSION: Setting the navigator under the left hepatic lobe for MRCP using PACE causes the data processing to be more difficult. As well, under current circumstances, it does not contribute to reducing acquisition time or improving the image quality.

Frequency of common bile duct motion artifacts caused by inferior vena cava pulsation on magnetic resonance cholangiopancreatography.

PURPOSE: We assessed the frequency of common bile duct (CBD) motion artifacts caused by inferior vena cava (IVC) pulsation on magnetic resonance cholangiopancreatography (MRCP). METHODS: We retrospectively evaluated CBD motion artifacts in 4 MRCP sequences from each of 115 consecutive patients. RESULTS: We observed 37 (32.2%) ghost artifacts at the ventral and dorsal aspects of the CBD on transaxial, half-Fourier acquisition single-shot turbo spin-echo (HASTE-ax) images; no such artifacts were observed on transaxial T(2)-weighted turbo spin-echo images. In 10 patients, we observed 9 (7.8%) pseudo-defects of the CBD on 3-dimensional T(2)-weighted turbo spin-echo with navigator-triggered prospective acquisition correction technique MRCP and 6 (5.2%) pseudo-defects on single-shot rapid acquisition with relaxation enhancement MRCP. Pseudo-defects were significantly more frequent in patients with ghost artifacts than without (9 of 37 [24.3%] versus one of 78 [1.3%]; P<0.01, McNemar test). CONCLUSION: Although uncommon, pseudo-defects of the CBD caused by IVC pulsation are observed on MRCP. MRCP interpretation that includes comparison with HASTE-ax images can diminish the potential misinterpretation of such CBD motion artifact as bile duct tumor or biliary stone.

Spermatic cord abscess with concurrent prostatic abscess involving the seminal vesicle.

Prostatic abscess involving the seminal vesicle has become rare following the development of effective antibiotic treatments. To our knowledge, we report the first case in the English-language literature of a patient with a spermatic cord abscess and a concurrent prostatic abscess. We examined an 81-year-old man for swelling and pain in the left inguinal region and performed computed tomography (CT) that later confirmed the suspected diagnosis of left inguinal hernial strangulation. We performed urgent surgical drainage of a left spermatic cord abscess; and under the correct diagnosis by CT, he was successfully treated further with antibiotics and transperineal drainage of a prostatic abscess extending to the seminal vesicle. We highlight that familiarity with such a rare condition is overwhelmingly essential for patient management and that CT is the most valuable imaging procedure for diagnosing such cases.

Computed tomographic appearance of urachal carcinoma associated with urachal diverticulum misdiagnosed by cystoscopy.

Urachal carcinoma associated with the urachal diverticulum is rare. We present a surgical case of this condition that was initially diagnosed as bladder urothelial carcinoma by cystoscopy, but was then correctly diagnosed by computed tomography (CT). Whereas the CT appearance mimicked that of bladder cancer, accurate localization of the lesion and identification of the median umbilical ligament clarified diagnosis.

Computed tomographic findings of syphilitic aortitis.

We describe the computerized tomographic (CT) findings of the aortic wall in a case of acute-phase syphilitic arteritis. The delayed phase of the contrast-enhanced CT shows a double-ring configuration of the thick thoracic aortic wall, which is similar to CT findings previously reported for Takayasu arteritis. We speculate that the resemblance of the CT findings for these two diseases accounts for their similar histopathological features.

A trial to measure local lung volume changes during respiration with CT.

PURPOSE: To evaluate changes in volume and the CT attenuation value of the pulmonary lobes and peripheral small lung tissue at full inspiration and expiration. MATERIALS AND METHODS: We designated (1000+CT insp)/(1000+CT exp)(1000+CT insp)/(1000+CT exp) as CT volume ratio, a new parameter to represent volume changes in lung tissue, and V insp/V exp as actual volume ratio: CT insp, exp: CT attenuation value of measured lung at inspiration and expiration; V insp, exp: actual lung volume measured with CT at inspiration and expiration. Ten normal healthy volunteers were investigated with 5 mm collimation CT in the supine position. RESULTS: The CT volume ratio and actual volume ratio of each lung lobe were well correlated. The CT volume ratios of small lung tissues were significantly larger in the dependent region than in the nondependent region when measured in the supine position at five levels, except at the level of the aortic arch (P<0.05). CONCLUSION: We advocated a new parameter (CT volume ratio) for representing lung tissue volume changes during respiration. The CT volume ratio might be a new noninvasive method to measure local volume changes in lung during respiration.

Helical CT features of arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC), also known as arrhythmogenic right ventricular dysplasia, is a disorder of the heart muscle of unknown origin. It is characterized by electrical instability of the heart as a result of replacement of the right ventricular myocardium with fatty or fibrous fatty tissue. Dilatation of the right ventricle; fatty tissue in conspicuous trabeculae of the right ventricle, especially in the anterior wall, apex, and inferior (diaphragmatic) wall; and a scalloped appearance (bulging) of the right ventricular wall are characteristic findings at helical computed tomography (CT) that may be used to diagnose ARVC. Fatty tissue in the left ventricle and ventricular septum is seen relatively frequently in ARVC, and fat in the ventricular septum is another useful finding for diagnosis of ARVC with helical CT. ARVC is usually diagnosed on the basis of clinical or pathologic findings, and electron-beam CT is superior to nongated helical CT in assessment of abnormal right ventricular function. However, with knowledge of the characteristic findings, standard nongated helical CT can be helpful in diagnosing ARVC.