Primary central nervous system lymphoma (PCNSL) mimicking a falx meningioma with increasingly massive intracerebral hemorrhage.

When using imaging to diagnose brain tumors, it is important to determine whether the tumor is intra- or extra-parenchymal. An 80-year-old man was found on magnetic resonance imaging to have an enhanced mass that appeared to be in the falx and a massive hematoma in the left frontal lobe; the provisional diagnosis was falx meningioma. However, the tumor and hematoma were found intraoperatively to be completely intraparenchymal. Additionally, the falx was intact and not adherent to brain tissue. Malignant lymphoma was diagnosed histologically on the basis of abnormal proliferation of atypical CD20-positive lymphocytes. Cerebral hemorrhage is an extremely rare presentation of primary central nervous system lymphoma. To the best of our knowledge, only 7 cases have been reported. All the reported cases had enhancement in the hematoma; however, in our case, there was definite enhancement outside the hematoma, making the correct diagnosis of lymphoma difficult.

Fulminant infectious endocarditis caused by Staphylococcus aureus with pseudoaneurysms in the superior mesenteric, hepatic, and popliteal arteries: a case report.

Staphylococcus aureus infectious endocarditis has a high mortality, major causes of death being cardiac failure, systemic embolism, and sepsis. Pseudoaneurysms, a rare complication of this infection, are not invariably fatal with appropriate treatment. A previously healthy 32-year-old man was found to have multiple cerebral infarctions, and infectious endocarditis with mitral valve vegetation was diagnosed by echocardiography. Because methicillin-resistant Staphylococcus aureus (MRSA) was identified from blood cultures, vancomycin was administered. Massive intracerebral hemorrhage in the left temporo-occipital lobe occurred in the patient on the 3rd day after admission, and the hematoma was completely removed surgically. Another hemorrhage was identified in the right occipital region on the 7th hospital day, which led the patient deep coma. Blood cultures on the 10th day were negative for MRSA; however, imaging studies revealed pseudoaneurysms in the superior mesenteric, hepatic, and left popliteal arteries 3 weeks after admission. No surgical indication was applied to these pseudoaneurysms because the patient remained comatose. On the 78th day after admission, the patient's blood pressure suddenly dropped and he died. Autopsy demonstrated massive bleeding in the abdominal cavity caused by rupture of the superior mesenteric artery pseudoaneurysm. Our patient's clinical course was fulminant, his endocarditis being complicated by cerebral infarctions, intracranial hemorrhages, and multiple pseudoaneurysms within 3 weeks of admission. In retrospect, he may have survived if emergency resection of the mitral valve vegetation had been performed on the first or second day of admission; however, the in-hospital mortality rate after such surgery is high.

Pseudoaneurysm of the Peroneal Artery After Ankle Arthrodesis Treated by Endovascular Coil Embolization: A Case Report.

CASE: Pseudoaneurysms of the peroneal artery around the ankle joint have rarely been reported. We present the case of a 64-year-old man with a pseudoaneurysm of the anterior perforating branch of the peroneal artery associated with a screw inserted from the anterolateral distal tibia during ankle arthrodesis. Endovascular treatment with selective catheterization and coil embolization was successfully performed. The ankle joint achieved bone union without delay, and the pseudoaneurysm did not recur at the 18-month follow-up. CONCLUSION: This is the first report describing a pseudoaneurysm of the peroneal artery after ankle arthrodesis. Successful outcomes can be achieved by endovascular treatment.

[Numerical and Visual Evaluation of Compressed Sensing MRI Using 3D Cartesian Sampling].

We performed numerical and visual evaluation of compressed sensing MRI (CS-MRI) using 3D Cartesian sampling by numerical simulation. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for numerical evaluation. Sampling ratio of the Cartesian grid was 30%. Reconstruction was performed by the projection onto convex sets (POCS) method with soft thresholding, subject to data fidelity constraints. In the absence of noise, RMSE of 3D-T1WI was 1.50, ant that of the 2D-T1WI of the transverse plane was in the range of 1.06 to 1.54; anatomical ROIs was in the range of 0.75 to 2.80; those of T2WI were 3.20, 2.77 to 3.06, and 1.81 to 4.51; those of PDWI were 1.69, 1.33 to 1.49, and 1.08 to 1.86. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, and tissue contrast. Average score of the visual evaluation indicated that anatomical structure and tissue contrast of CS images were equal to those of the original image, although a few artifacts were visible. If noise level was assumed to be 20 dB or less, anatomical structure and tissue contrast were not significantly degraded compared to noise-free CS images.

Magnetic Resonance Imaging of a Urethral Caruncle and the Pathologic Correlation: A Report of 3 Cases.

A urethral caruncle is the most common disease of the urethra in postmenopausal women. A definitive diagnosis can usually be reached based on physical examination. Cross-sectional imaging is performed when malignant urethral tumor is suspected, such as a urethral carcinoma. No articles have discussed the detailed imaging of urethral caruncles. We present 3 patients with symptomatic urethral caruncles who underwent magnetic resonance imaging preoperatively.

[Numerical and Visual Evaluations of Compressed Sensing MRI Using 2D Radial Sampling].

Two-dimensional radial MRI using compressed sensing (2D radial CS) enables incoherence sampling in k space unlike conventional Cartesian MRI, however 2D radial CS has not been sufficiently investigated. Numerical and visual evaluations of 2D radial CS were performed in this paper. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weigthted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for the numerical evaluation. The Brainweb MRI Data Base was used for test images. Projection of 80 spokes with linear sampling of 256 pixels was used. Reconstruction was performed by minimizing the L1 norm of a transformed image using wavelet transform and spatial finite-differences (total variation), subject to data fidelity constraint. In the absence of noise, the root mean square error (RMSE) of T1WI was in the range of 3.75 to 5.05; that of the anatomical region of interests (ROIs) was in the range of 1.54 to 10.24; those of T2WI were 8.75 to 11.65 and 4.31 to 6.99; and those of PDWI were 3.44 to 4.46 and 1.34 to 3.09. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, and tissue contrast. Average percent scores of the visual evaluation were 96% for T1WI, 74-81% for T2WI, and 81-89% for PDWI.

[Numerical and Visual Evaluations of Compressed Sensing MRI Using 2D Cartesian Sampling].

This paper describes numerical and visual evaluations of compressed sensing MRI (CS-MRI) using 2D Cartesian sampling by numerical simulation. The BrainWeb MRI Data Base was used for test images. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for the numerical evaluation. Sampling ratio was 50%. Reconstruction was performed by minimizing the L1 norm of a transformed image using wavelet transform and total variation, subject to data fidelity constraints. The conjugate gradient method was used in the minimization of the object function. In the absence of noise, the root mean square error (RMSE) of T1WI was in the range of 2.99 to 3.57; that of the anatomical region of interests (ROIs) was in the range of 1.77 to 8.53; those of T2WI were 4.72 to 5.65 and 3.28 to 5.54; and those of PDWI were 1.91 to 2.36 and 1.32 to 2.09. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, tissue contrast. CS image quality was nearly equal to that of the original image, although a few artifacts were visible. If the noise level was assumed to be 30 dB or less, T1-CS image and PD-CS images were not significantly degraded compared to noise-free images.

Neuroendocrine carcinoma arising in a hepatitis C virus-infected liver: mechanism of the tumor development may be similar to that of development of pancreatic neuroendocrine cells.

We experienced a case of neuroendocrine carcinoma (NC). The tumor developed in the cirrhotic liver of a 62-year-old Japanese man who had been infected with hepatitis C virus. The tumor cells showed high N/C ratio, formed many rosettes, and expressed CD56, synaptophysin, HepPar1 and pancreatic and duodenal homeobox 1. MIB1 expression was 65%. Because both liver and pancreas are derived from a common endodermal layer during fetal development, we speculated that the tumor may have formed via the interaction of neurogenin 3, insulinoma-associated 1 gene and NeuroD/beta2, which are involved in the stage at which some pancreatic cells commit to becoming endocrine cells. Molecular analysis revealed that the NC had higher relative expression levels of mRNA of the three molecules than did the nontumorous liver. The results indicate that the NC in this patient may have formed via the same mechanism that acts in the development of pancreatic neuroendocrine cells.

CT urography in the urinary bladder: to compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter.

BACKGROUND: Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure. PURPOSE: To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF). MATERIAL AND METHODS: Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI(vol)) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale. RESULTS: The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI(vol) demonstrated a 73% reduction in group B (4.6 ± 1.1 mGy) compared with group A (16.9 ± 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 ± 5.1) and group B (16.6 ± 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences. CONCLUSION: EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise.

[Evaluation of ultra-low-dose thoracic multi-detector-row CT using different reconstruction kernels and new reconstruction algorithms].

CT has great advantages in detecting early-stage small lung cancer and is becoming common in lung cancer screening. Multi-detector-row CT (MDCT) can provide thin-slice images with low radiation exposure. In this study, ultra-low-dose (5 mAs: 10 mAs, 0.5 sec/rot) thoracic MDCT images were evaluated. We describe the differences in image quality and quantity between the different reconstruction kernels. We also propose a new reconstruction algorithm (ultra-low-dose reconstruction algorithm: ULR) for ultra-low-dose thoracic CT, to reduce noise and streak artifacts. We are convinced of the usefulness and possibility of ultra-low-dose thoracic MDCT with ULR algorithms for lung cancer screening.

Spontaneous resolution of an idiopathic cervical direct vertebral arteriovenous fistula after partial coil embolization in a patient presenting with myeloradiculopathy.

A 53-year old female presented with paresis of the left upper extremity. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) disclosed a single high-flow vertebral arteriovenous fistula (AVF) with vertebral artery (VA) transection. The AVF was also fed by steal flow from the contralateral VA. The left posterior inferior cerebellar artery (PICA) branched just distal to the fistula. The fistula drained into the neighboring paravertebral veins and refluxed into the intradural venous systems. The dilated drainers compressed the spinal cord. Embolization was attempted at the drainer just behind the fistula orifice using platinum coils. The fistula was still fed slightly by right VA after the embolization, but spontaneous complete obliteration was achieved after one week. The clinical symptoms and signs disappeared. Although, detachable balloon embolization is the quickest and most effective procedure to obliterate a fistula, stepwise embolization using GDC can be considered, and may avoid the normal pressure perfusion break-through phenomenon. Spontaneous obliteration of the fistula after partial embolization in our case may result from intravenous embolization just behind the fistula orifice. It may therefore be a useful approach to the embolization of an AVF to begin the embolization at the venous side of the fistula.