Malleus bar as a rare cause of congenital malleus fixation: CT demonstration

Among congenital ossicular anomalies without external ear atresia, malleus fixation is least common. We report a case of congenital malleus fixation by a bony bar connecting the malleus neck to the posterior tympanic wall, which was depicted on thin-section CT scans.

Tc-99m diethylenetriamine pentaacetic acid (DTPA)-human serum albumin (HSA) radionuclide lymphography for detecting the location of chyluria

The cause of chyluria cannot be easily detected by CT scan or other imaging methods, except conventional lymphography, but Tc-99m diethylenetriamine pentaacetic acid radionuclide lymphography clearly revealed the location of chyluria in the left renal pelvic area. Radionuclide lymphography is one of the choices in investigating chyluria due to its noninvasive and simple technique.

Ductectatic mucinous cystic neoplasms of the pancreas: evaluation with MR cholangiopancreatography

OBJECTIVE

We performed this study to describe the advantages of MR cholangiopancreatography and its findings in revealing ductectatic mucinous cystic neoplasms of the pancreas.

CONCLUSION

MR cholangiopancreatography using both projection and source images can reveal characteristic findings of a ductectatic mucinous cystic lesion of the pancreas and show the presence of the communicating duct between the cystic lesion and the main pancreatic duct.

Uterus didelphys associated with obstructed hemivagina and ipsilateral renal agenesis: MR findings in seven cases

BACKGROUND

Although a specific syndrome of the uterus didelphys, obstructive hemivagina, and ipsilateral renal agenesis had been reported in gynecologic literatures, it is not familiar to radiologists. We introduce this syndrome with radiological, especially MR findings.

METHODS

Imaging findings and medical records of seven patients with this syndrome were retrospectively reviewed.

RESULTS

MR clearly demonstrated uterus didelphys with obstructed hemivagina in six of the seven patients. A remaining one showed uterus didelphys with left-sided hematometra and hematosalpinx who had undergone vaginal septum incision prior to the MR. We could also recognize ipsilateral renal agenesis in all five patients, in whom renal areas were examined on MR. After vaginal septum resection, symptoms disappeared in six patients. We could observe the disappearance of the obstructive complications with MR in three patients.

CONCLUSIONS

MR can do much for the early diagnosis and the prevention against further complications of this condition because it can demonstrate the müllerian duct anomaly complicated with obstructed hemivagina in detail and even ipsilateral renal agenesis.

Well-differentiated liposarcoma of the retroperitoneum with a fat-fluid level: US, CT, and MR appearance

We report a case of retroperitoneal liposarcoma with a fat-fluid level that has not been previously described. A 36-year-old man presented with abdominal distension. Ultrasonography, CT, and MR imaging showed a tumor with a fat-fluid level; nondependent fluid was characteristic of fat. Liposarcoma should be included in the differential diagnosis of tumors exhibiting a fat-fluid level.

High-spatial-resolution and real-time medical imaging using a high-sensitivity HARPICON camera

A HARPICON(TM) camera has been applied to a digital angiography system with fluorescent-screen optical-lens coupling. It uses avalanche multiplication in the photoconductive layer for high-sensitivity imaging. The limiting spatial resolutions in the 1050 scanning-line mode of the camera are about 30 and 50 micro m at input field sizes of 20 x 20 and 50 x 50 mm on the screen, respectively. For high-speed imaging, the 525 scanning-line mode at a rate of 60 images s(-1) can be selected. High-quality images of coronary arteries in dogs were obtained by intra-aortic coronary angiography and superselective coronary angiography using a single-energy X-ray above the iodine K-edge energy.

Medical applications with synchrotron radiation in Japan

In Japan, various medical applications of synchrotron X-ray imaging, such as angiography, monochromatic X-ray computed tomography (CT), radiography and radiation therapy, are being developed. In particular, coronary arteriography (CAG) is quite an important clinical application of synchrotron radiation. Using a two-dimensional imaging method, the first human intravenous CAG was carried out at KEK in May 1996; however, further improvements of image quality are required in clinical practice. On the other hand, two-dimensional aortographic CAG revealed canine coronary arteries as clearly as those on selective CAG, and coronary arteries less than 0.2 mm in diameter. Among applications of synchrotron radiation to X-ray CT, phase-contrast X-ray CT and fluorescent X-ray CT are expected to be very interesting future applications of synchrotron radiation. For actual clinical applications of synchrotron radiation, a medical beamline and a laboratory are now being constructed at SPring-8 in Harima.

MRI of mucosal malignant melanoma of the head and neck

PURPOSE

The objective of this study was to determine the characteristic MR findings for mucosal malignant melanomas of the head and neck.

METHOD

We retrospectively analyzed the MR images for six patients with this entity. T1-weighted SE images with and without gadolinium and T2-weighted fast SE images were obtained. MR images were analyzed qualitatively and quantitatively by comparing the signal intensity of the melanoma with that of muscle.

RESULTS

On T1-weighted images, five melanomas were hyperintense and one was isointense. On T2-weighted images, five were of mixed intensity and one showed isointensity. The mean signal intensity ratio of the primary melanoma to muscle was 1.51 and 1.39 on T1-weighted images with and without gadolinium, respectively. These values were not statistically significant.

CONCLUSION

Hyperintensity on T1-weighted images is characteristic of this entity, but not universal.

Phase-contrast X-ray CT image of breast tumor

Phase-contrast X-ray CT images generated by differences in refractive indices can be used to visualize the internal structures of soft tissues without contrast enhancement. In this study, imaging of human breast tumor was performed on formalin-fixed samples. Experiments were carried out at the synchrotron source of the Photon Factory, Tsukuba, Japan. The X-ray energy was adjusted to 17.7 keV. Phase-contrast X-ray CT images revealed various structures of human breast tumor as clearly as optical images.

Development of a two-dimensional imaging system for clinical applications of intravenous coronary angiography using intense synchrotron radiation produced by a multipole wiggler

A two-dimensional clinical intravenous coronary angiography system, comprising a large-size view area produced by asymmetrical reflection from a silicon crystal using intense synchrotron radiation from a multipole wiggler and a two-dimensional detector with an image intensifier, has been completed. An advantage of the imaging system is that two-dimensional dynamic imaging of the cardiovascular system can be achieved due to its two-dimensional radiation field. This world-first two-dimensional system has been successfully adapted to clinical applications. Details of the imaging system are described in this paper.

Von Meyenburg complexes of the liver: imaging findings

PURPOSE

Our purpose was to present imaging findings of six cases proven or supposed to be von Meyenburg complexes (VMCs) with a basis of reviewing the pathologic literature and to describe imaging points for the diagnosis of typical VMC along with its differential diagnosis.

METHOD

Six cases were diagnosed as VMC of the liver with imaging modalities (one had histopathologic proof). Both ultrasound (US) and CT were available for all cases, and MRI was used for three cases. Follow-up with US, CT and/or MRI was performed in five cases.

RESULTS

US detected varying abnormalities of the livers in four cases. CT and MRI revealed multiple or numerous intrahepatic tiny (usually < 5 mm) cystoid lesions in all of the cases. The lesions were scattered throughout the livers, and some of them were located more frequently adjacent to the medium-sized portal veins than to the hepatic veins of similar size on CT. Moreover, some lesions were apparently located in the subcapsular areas (up to the hepatic capsules). They were usually irregular in shape and showed no enhancement but increased in number by approximately 80-150% after administration of intravenous contrast medium. The T2-weighted MR images and MR cholangiopancreatography showed the lesions to be much more apparent and to be more numerous than T1-weighted images did. Follow-up of five cases with imaging modalities did not show remarkable change of the lesions.

CONCLUSION

Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.

[Medial collateral ligament of the knee and its surroundings: MRI findings of normal and abnormal structures]

Normal and abnormal structures of the medial corner of the knee were evaluated with coronal and axial MR images. MRI revealed 35 medial collateral ligament (MCL) tears and 61 medial meniscus (MM) tears in 200 consecutive examinations. Just under the MCL, little or no fluid retention was identified between the superficial and deep layers of the MCL or between the MM and MCL in normal knees and in cases of MM tears. At the anterior aspect of the MCL, the deep layer merges with the capsule of the suprapatellar bursa, potentially leaving space for fluid retention. Fluid collection posterior to the MCL was demonstrated in a few cases. Fluid retention with edematous swelling just under the MCL was noted in the cases of MCL tears. MM-MCL distances in the cases of normal structure, MM tears and MCL tears were 2.1 mm, 2.7 mm and 4.7 mm, respectively. The deep layer of the MCL, which was enhanced by the presence of joint fluid, was identified in 71% of cases.

Phase-Contrast Tomographic Imaging Using an X-ray Interferometer

Apparatus for phase-contrast X-ray computed tomography using a monolithic X-ray interferometer is presented with some observational results for human breast tissues. Structures characteristic of the tissues were revealed in the phase-contrast tomograms. The procedure of image analysis consists of phase retrieval from X-ray interference patterns and tomographic image reconstruction from the retrieved phase shift. Next, feasibility of phase-contrast imaging using a two-crystal X-ray interferometer was studied aiming at in vivo observation in the future. In a preliminary study, the two-crystal X-ray interferometer was capable of generating fringes of 70% visibility using synchrotron X-rays.

Mature teratoma of the posterior mediastinum

The vast majority of germ cell tumors in the thorax arise at or near the thymus. We report a case of a 41-year-old man with mature teratoma of the posterior mediastinum. He was asymptomatic and was incidentally found to have a posterior mediastinal mass. Computed tomography was helpful in suggesting a diagnosis of mature teratoma by demonstrating the presence of fat and calcification. The differential diagnosis included neurogenic tumors, liposarcoma, and extramedullary hematopoiesis.

Slightly flexed knee position within a standard knee coil: MR delineation of the anterior cruciate ligament

The purpose of this study was to assess the value of positioning the knee slightly flexed within a standard MR knee coil in delineation of the anterior cruciate ligament (ACL). Within the confined space of a commercially available knee coil, knee could bend as much as 30 degrees , average 17 degrees of flexion. Sets of oblique sagittal MR images were obtained at both fully extended and slightly flexed positions. Twenty-two normal knees and 18 knees with ACL tears were examined and paired MR images were evaluated by two observers. Compared with knee extension, the MR images for knee flexion provided better clarity in 57 % of reviews of full length of the ACL and 53 % of the femoral attachment. In the extended position the anterior margin of the ligament was obscured due to partial averaging with the intercondylar roof. We recommend examining the knee in an achievable flexed position within the standard knee coil.

[Arterial redistribution of extrahepatic collaterals to the liver under temporary balloon occlusion of the proper hepatic artery]

Three patients with liver metastases receiving transarterial chemotherapy underwent embolization of extrahepatic collaterals to the liver under temporary balloon occlusion of the proper hepatic artery. Enhancement in the liver and tumors was observed at CT arteriography through the right inferior phrenic artery and was accentuated under balloon occlusion in all patients. A Cyanoacrylate-Lipiodol mixture was infused through the right inferior phrenic artery to occlude arterial communications with intrahepatic arteries. Better contrast agent distribution was obtained in all patients after embolization. It is suggested that this procedure can be effective for arterial redistribution against extrahepatic collaterals to the liver.

Relationship between normalization of negative T waves on exercise ECG and residual myocardial viability in patients with previous myocardial infarction and no post-infarction angina

The usefulness of normalization of negative T waves in exercise ECG was investigated as an index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise test. A total of 39 patients, 20 with T-wave normalization (POS group) and 19 without T-wave normalization (NEG group) on exercise ECG. were studied. Myocardial viability was evaluated by thallium-201 single-photon emission computed tomography (SPECT) during exercise or at rest. We also assessed left ventricular ejection fraction (LVEF) by contrast ventriculography before (n=39) and after percutaneous transluminal coronary angioplasty (PTCA) (n=17). SPECT detected myocardial viability in 16 (80%) of the 20 patients in the POS group and in 4 (21%) of the 19 patients in the NEG group (p<0.01). LVEF increased after successful PTCA in the POS group (from 53+/-13% to 63+/-8%, p<0.025), but fell in the NEG group (from 57+/-10% to 51+/-8%). It is concluded that normalization of negative T waves on exercise ECG is a useful, simple index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise testing.

[Usefulness of a new technique to assess drug perfusion pattern on balloon occluded arterial infusion therapy (BOAI) for intrapelvic malignant neoplasms: subtraction CT with low-flow-rate arterial injection (S-CTLA)]

The hemodynamics in balloon occluded arterial infusion therapy (BOAI) for intrapelvic malignant neoplasms is not totally understood. A new technique to evaluate the perfusion pattern of anticancer drugs under BOAI, which is named Subtraction CT with Low-flow-rate Arterial injection (S-CTLA), has been developed by us. In this technique, spiral CT data were acquired twice, before and after low-flow-rate (0.2 ml/sec) injection of contrast agent. Then, subtraction images were reconstructed. S-CTLA was performed in 3 patients with urinary bladder cancer. Our results provided demonstrable images as well as useful information in predicting the effectiveness of BOAI.

Central dot sign in entities other than Caroli disease

OBJECTIVE

The purpose of this study was to describe central dot sign (tiny dots with strong contrast enhancement of the portal vein within dilated hepatic bile ducts on computed tomography) in entities other than Caroli disease, especially in peribiliary cysts with or without autosomal-dominant polycystic kidney disease.

MATERIALS AND METHODS

Computed tomography in 74 cases of peribiliary cysts and 134 cases of other liver diseases and states possibly showing central dot sign were retrospectively reviewed to examine the central dot sign.

RESULTS

In three cases of peribiliary cysts, some part of the liver showed strongly enhanced portal radicles surrounded completely or partially by low-attenuation, enlarged peribiliary cysts, presenting "central dot sign" on contrast-enhanced computed tomography.

CONCLUSION

We suggest that in addition to Caroli disease, some other entities and diseases of the liver may demonstrate central dot sign and this sign should not be considered a specific finding of Caroli disease.

CT of the medial umbilical folds

PURPOSE

The goal of our study was to investigate the appearance of the medial umbilical folds on CT.

METHOD

We retrospectively reviewed the CT images of 30 consecutive patients with massive ascites. In addition, we inspected the inner pelvic wall in cadavers.

RESULTS

The medial umbilical folds were well recognized on CT in 21 of 30 patients, bilaterally in 20 and unilaterally in 1. In four patients the folds were undetectable after the ascites resolved. The CT findings were supported by those studied in cadavers, in which the folds were recognized as a peritoneal reflection in 13 of 20.

CONCLUSION

We concluded that medial umbilical folds could be commonly visualized on CT when ascites was present.

Hepatic peribiliary cysts: increases in size and number on computed tomography

We report a 71-year-old male patient with multiple hepatic peribiliary cysts. The six-year follow-up through computed tomography (CT) imaging revealed increases in the size (from less than 10 mm to more than 38 mm) and number of the cysts.

[Functional MRI employing diazepam; a proposal of neuropharmacological fMRI]

Employing the active benzodiazepine receptor (BZR) ligands, we have used BOLD fMRI to elucidate the effects of these drugs on brain function. The sequential MRI was performed with a 1.5T clinical scanner (Philips GYROSCAN) using a FLASH sequence with the following parameters: TR/TE, 100/45 msec; flip angle, 25 degrees; matrix size, 128*128; 2 averages; for 64 image acquisitions in 32 min. First, 2 mg of diazepam was administrated intravenously at the beginning of the 5th, 15th, 25th, and 35th acquisitions. Then, flumazenil was administrated at the beginning of the 45th (0.2 mg) and 55th (0.3 mg) acquisitions in order to reverse the effect of diazepam. Data processing was made employing Akaike Information Criterion to detect if there were intensity changes after the medication among the trends of intensity changes. Diazepam administration decreased the intensity for a while and flumazenil increased one. In the case of the left frontal glioma with focal epileptogenicity, intensity changes were detected around the tumor. Since the neuronal function consists of the trans-neuronal communications employing neurotransmitters, the result on the modulation of this passage depends on the neuronal function related to the transmitter: gamma-amino butyric acid (GABA) in this instance for the effects of these medications to epilepsy. The change in the local blood flow is the result of the local neuronal activity. Therefore, we speculate that this neuropharmacological functional MR image may reflect the neuronal function related to the GABAegic neurotransmitter system. In addition to elucidating basic neurotransmitter function mechanisms, we believe this technique may have clinical utility in the pre-surgical evaluation of patients with intractable seizure disorders. In this respect, this paper presents a new spectrum of fMRI that is capable to study a part of neurotransmitter function employing the BZR ligands, reversing the effect of the agonist with the competitive antagonist, for the first experience, to propose the neuropharmacological functional MR images to have clinical utility in patients with intractable epilepsy in the interictal state.