Topogram-based tube current modulation of head computed tomography for optimizing image quality while protecting the eye lens with shielding.

BACKGROUND: Multiple rounds of head computed tomography (CT) scans increase the risk of radiation-induced lens opacification. PURPOSE: To investigate the effects of CT eye shielding and topogram-based tube current modulation (TCM) on the radiation dose received by the lens and the image quality of nasal and periorbital imaging. MATERIAL AND METHODS: An anthropomorphic phantom was CT-scanned using either automatic tube current modulation or a fixed tube current. The lens radiation dose was estimated using cropped Gafchromic films irradiated with or without a shield over the orbit. Image quality, assessed using regions of interest drawn on the bilateral extraorbital areas and the nasal bone with a water-based marker, was evaluated using both a signal-to-noise ratio (SNR) and contrast-noise ratio (CNR). Two CT specialists independently assessed image artifacts using a three-point Likert scale. RESULTS: The estimated radiation dose received by the lens was significantly lower when barium sulfate or bismuth-antimony shields were used in conjunction with a fixed tube current (22.0% and 35.6% reduction, respectively). Topogram-based TCM mitigated the beam hardening-associated artifacts of bismuth-antimony and barium sulfate shields. This increased the SNR by 21.6% in the extraorbital region and the CNR by 7.2% between the nasal bones and extraorbital regions. The combination of topogram-based TCM and barium sulfate or bismuth-antimony shields reduced lens doses by 12.2% and 27.2%, respectively. CONCLUSION: Image artifacts induced by the bismuth-antimony shield at a fixed tube current for lenticular radioprotection were significantly reduced by topogram-based TCM, which increased the SNR of the anthropomorphic nasal bones and periorbital tissues.

Sonographic criteria predictive of benign thyroid nodules useful in avoiding unnecessary ultrasound-guided fine needle aspiration.

BACKGROUND/PURPOSE: There has been no individual ultrasound feature of having high accuracy for diagnosis of thyroid malignancy. In this study, we aimed to establish feature-oriented criteria to characterize benign thyroid nodules that do not require ultrasound (US)-guided fine needle aspiration (FNA). METHODS: We reviewed 374 patients with thyroid nodules who had undergone US-guided FNA at our institution (2005-2008). Thyroid nodules were classified into two groups: Category 1 (benign nodules that required follow-up 6-12 months later but not US-guided FNA); and Category 2 (indeterminate nodules or suspected carcinoma that required US-guided FNA). To test the validity, we reviewed 315 consecutive patients who had histologically proven thyroid carcinoma (n = 39) and randomly selected 40 of the 276 patients with benign nodules (2009-2010). RESULTS: Of 374 nodules, 354 (95%) were benign and 20 (5%) malignant. On US, 260 nodules had no calcification, no increase in vascularity, well-defined margin, and no lymphadenopathy (Category 1). Using a combination of these four features, we were able to discriminate benign from indeterminate nodules or suspected malignant nodules with a sensitivity of 73%, and specificity and positive predictive value of 100%. Validity testing revealed that none of the 39 malignant thyroid nodules had all four US features. All Category 1 nodules (2005-2008) remained benign at the 3-years follow up. CONCLUSION: The combination of four US features of Category 1 nodules is highly predictive of benign disease, and we could avoid unnecessary US-guided FNA in 69.5% of our patients using this combined features.

Fusobacterium septicemia complicated by cerebral subdural and epidural empyemas: a rare case of Lemierre syndrome.

BACKGROUND: Lemierre syndrome is characterized by postanginal septicemia and internal jugular vein thrombophlebitis with secondary septic emboli, typically to the lungs. The central nervous system (CNS) is rarely involved. OBJECTIVE: To present a case of Lemierre syndrome featuring cerebral subdural and epidural empyemas. CASE REPORT: This case report describes the case of a 17-year-old youth with cerebral subdural and epidural empyemas. The findings of chest computed tomography of the neck and the blood cultures were compatible with Lemierre syndrome. The patient recovered well after antibiotic treatment and surgical debridement. CONCLUSION: Lemierre syndrome can result in infection spreading to the CNS, including cerebral subdural and epidural empyemas. This disease entity should be included in the differential diagnoses of CNS bacterial infections.

Leptomeningeal metastasis of malignant lymphoma with negative results in magnetic resonance imaging: a case report.

PURPOSE: Non-Hodgkin's lymphoma which occasionally involves the central nervous system, occurs more often in high-grade cases and implicates a poor prognosis. Leptomeningeal metastases may present as multiple cranial nerve involvements. Diagnosis is achieved by recognizing the clinical manifestations, followed by neuroradiologic studies and laboratory examination of the cerebrospinal fluid. But normal studies of either method do not exclude such a diagnosis. CASE REPORT: We present one female patient with non-Hodgkin's lymphoma, who had multiple cranial nerve palsies as signs of central nervous system involvement, but who had negative results in her neuroimaging studies. CONCLUSION: Patients with multiple cranial nerve palsies should receive cytological examinations of the cerebrospinal fluid in spite of the negative neuroimaging results.

Intensity of arterial structure acquired by Silent MRA estimates cerebral blood flow.

BACKGROUND: Cerebral blood flow (CBF) and the morphology of the cerebral arteries are important for characterizing cerebrovascular disease. Silent magnetic resonance angiography (Silent MRA) is a MRA technique focusing on arterial structural delineation. This study was conducted to investigate the correlation between Silent MRA and CBF quantification, which has not yet been reported. METHODS: Both the Silent MRA and time-of-flight magnetic resonance angiography scans were applied in seventeen healthy participants to acquire the arterial structure and to find arterial intensities. Phase-contrast MRA (PC-MRA) was then used to perform the quantitative CBF measurement of 13 cerebral arteries. Due to different dataset baseline signal level of Silent MRA, the signal intensities of the selected 13 cerebral arteries were normalized to the selected ROIs of bilateral internal carotid arteries. The normalized signal intensities were used to determine the relationship between Silent MRA and CBF. RESULTS: The image intensity distribution of arterial regions generated by Silent MRA showed similar laminar shape as the phase distribution by PC-MRA (correlation coefficient > 0.62). Moreover, in both the results of individual and group-leveled analysis, the intensity value of arterial regions by Silent MRA showed positively correlation with the CBF by PC-MRA. The coefficient of determination (R2) of individual trends ranged from 0.242 to 0.956, and the R2 of group-leveled result was 0.550. CONCLUSIONS: This study demonstrates that Silent MRA provides valuable CBF information despite arterial structure, rendering it a potential tool for screening for cerebrovascular disease.

Malignant fibrous histiocytoma of the heart: a case report.

Malignant fibrous histiocytoma (MFH) in the heart is rare. We present a case of a 38-year-old woman with histologically confirmed MFHs in the left atrium, liver and bone. The patient presented with shortness of breath and right shoulder pain. A plain radiograph showed an osteolytic lesion at the neck of the humerus on the right side. A computed tomography (CT) scan of the chest showed a lobulated tumour occupying the cardiac left atrium and a large heterogeneously enhancing mass in the liver and osteolytic metastasis in the thoracic spine. The patient underwent complete resection of the cardiac tumour, and histology showed a high-grade pleomorphic sarcoma--an MFH. Biopsy of the lesions on the right shoulder and in the liver also showed the same histologic diagnosis.

Anatomical relationships between medullary veins and three types of deep-seated malignant brain tumors as detected by susceptibility-weighted imaging.

BACKGROUND: Deep-seated brain tumors can be difficult to differentiate. Three tumor types (primary central nervous system lymphoma [PCNSL], high-grade glioma, and metastatic brain tumors), identified by susceptibility-weighted imaging, have different relationships with small medullary veins, and these relationships can be used to enhance diagnostic accuracy. METHODS: Records of patients with pathology confirmed malignant brain tumors who received susceptibility-weighted imaging between 2009 and 2015 were reviewed. A total of 29 patients with deep-seated malignant brain tumors in the territory of small medullary veins were enrolled in this study. The sensitivity, specificity, and diagnostic accuracy of medullary vein blockage (MVB), defined as a small medullary vein terminating at the margin of the tumor, for indicating malignant brain tumors were analyzed. RESULTS: Of 11 patients with PCNSLs, 5 with high-grade gliomas, and 13 with metastases, only the latter presented MVBs. The sensitivity, specificity, and accuracy of using MVBs for diagnosing metastatic tumors were 76.9%, 100%, and 89.7%, respectively. CONCLUSION: An MVB is an accurate sign for differentiating metastatic brain tumors from two other common malignancies and thus provides a useful tool for preoperative planning.

Inter- and Intra-Rater Reliability of Individual Cerebral Blood Flow Measured by Quantitative Vessel-Flow Phase-Contrast MRI.

Vessel flow quantification by two-dimensional (2D) phase-contrast magnetic resonance imaging (PC-MRI) using a three-dimensional (3D) magnetic resonance angiography (MRA) model to measure cerebral blood flow has unclear analytical reliability. The present study aimed to determine the inter- and intra-rater reliability of quantitative vessel-flow PC-MRI and potential factors influencing its consistency. We prospectively recruited 30 Asian participants (aged 20-90 years; 16 women; 22 healthy and 8 stroke patients) for performing 1.5-T MR equipped with a head coil. Each participant was first scanned for time-of-flight magnetic resonance angiography (TOF-MRA) images for localization of intracranial arteries. The 2D PC-MRI for each cerebral artery (total 13 arteries in fixed order) was performed twice by two well-trained operators in optimal position. Using the same 3D MRA as a map and facilitated with the non-invasive optimal vessel analysis (NOVA) system, each scan was taken on a plane perpendicular to the target artery. Two consecutive full 13-artery scans were performed at least 15 min apart after participants were removed from the scanner table and then repositioned. A total of four PC flow images obtained from each target artery were transmitted to a workstation facilitated with the NOVA system. Flow data were calculated semi-automatically by the NOVA system after a few simple steps. Two-way mixed-effect models and standard errors of measurements were used. In 13 cerebral arteries, repeatability, using the intra-rater estimate expressed as the average-measures intraclass correlation coefficient, ranged from 0.641 to 0.954, and reproducibility, using the inter-rater estimate, ranged from 0.672 to 0.977. Except in the middle cerebral artery and the distal segment of the anterior cerebral artery, repeatability and reproducibility were excellent (intraclass correlation coefficient exceeded 0.8). The use of quantitative vessel-flow PC-MRI is a precise means to measure blood flow in most target cerebral arteries. This was evidenced by inter-rater and intra-rater correlations that were good/excellent, indicating good reproducibility and repeatability.

Eye Shielding During Head CT Scans: Dose Reduction and Image Quality Evaluation.

RATIONALE AND OBJECTIVES: In this study, we assessed the radiation dose to the lens and the impacts of various eye shields using either a fixed or modulated tube current. MATERIALS AND METHODS: Patients undergoing head computed tomography (CT) examinations were recruited, and each was randomly assigned to one of five imaging groups, either without a CT eye shield or with one of two types of shielding and topogram-based tube current modulation (TCM). The radiation dose at the eye lens was estimated using Gafchromic films. All CT images were analyzed for quality in the orbit and brain areas. Two radiologists also qualitatively assessed image artifacts and their impacts on image quality using three-point Likert scales. RESULTS: Both barium sulfate and bismuth-antimony shields significantly reduced radiation dose to the lens (by 28.60%-31.92% and 43.87%-47.00%, respectively) while significantly inducing image artifacts. The image quality of the intraocular structure, but not the intracranial structure, was significantly degraded by shielding. In addition, discriminating the periocular tissues was improved using a bismuth-antimony shield and topogram-based TCM. Compared to fixed tube current, topogram-based TCM provided better signal-to-noise and contrast-to-noise ratios in the intracranial structures when the bismuth-antimony and barium sulfate shields were applied, respectively. CONCLUSION: Artifacts resulting from the application of eye shields during head CT examinations can be reduced by using topogram-based TCM instead of a fixed tube current. This could be an alternative approach for maintaining image quality in CT scans that do not encompass organ-based TCM.

Combined native magnetic resonance angiography, flow-quantifying, and perfusion-imaging for impending second-stroke assessment.

This special report introduces native flow quantitative imaging for evaluating stroke risk. Moreover, the advantage of combining three imaging techniques [magnetic resonance angiography (MRA), phase-contrast (PC) flow imaging, and arterial spin-labeling imaging] is shown to be beneficial for responding to ischemia and preserving viable neurons. These quantitative imaging techniques provide authoritative information for diagnosing impending stroke and selecting appropriate treatment.

Solitary cystic metastatic lymph node of occult human papillomavirus-related oropharyngeal cancer mimicking second branchial cleft cyst: A case report.

RATIONALE: Human papillomavirus (HPV)-related oropharyngeal cancer is becoming more common, the primary cancer AQ4 usually occult and appearing only as cystic cervical lymph node (LN) metastasis. Distinguishing between a benign cystic lesion and cystic LN metastasis is challenging given their similar radiologic and histologic appearances. PATIENT CONCERNS: A 54-year-old man presented with a bulging cystic mass measuring 6.4cm on the right side of neck. DIAGNOSES: Postexcision diagnosis was second branchial cleft cyst. After 2 years, the cystic mass recurred, and HPV-related tonsillar squamous cell carcinoma with cystic metastatic LNs was confirmed after wide tonsillectomy and neck dissection. The previous cystic lesion proved to be a cystic metastatic LN from the same malignancy with additional p16 immunostain. INTERVENTIONS: The patient was treated with adjuvant concurrent chemoradiation therapy. OUTCOMES: The patient was followed up in the outpatient department with no evidence of recurrence after 1 year. LESSONS: When an adult has a cystic mass in the upper neck, we must rigorously exclude it as a cystic metastatic LN of occult HPV-related oropharyngeal cancer. Additional p16 staining might be helpful.

MRI of hemangioblastoma in the conus medullaris.

Hemangioblastoma of the conus medullaris with MRI has not been reported before. A 75-year-old man had a history of falling due to weakness of his left lower limb. MRI revealed a well-defined oval mass in the conus medullaris. The tumor had an isointense signal relative to spinal cord on T1-weighted images, hyperintense signal areas intermixed with punctate spots of hypointensity on T2-weighted images, and heterogeneous obvious enhancement on gadolinium-enhanced T1-weighted images. Associated abnormally tortuous vessels were noted in the dura proximal to the tumor. Histological findings were compatible with the diagnosis of hemangioblastoma. Hemangioblastoma should be included in the differential diagnosis in patients with an enhancing tumor and adjacent engorged vessels of the spinal cord.

Magnetic resonance imaging of gluteal intramuscular myxoma.

Gluteal intramuscular myxomas with MR images have not been reported before. A 45-year-old man presented with a palpable mass in his right buttock for several months. Magnetic resonance imaging showed an intramuscular cystic lesion with homogeneous signal intensity at the right gluteus muscle, and the mass had thin peripheral enhancement after gadolinium administration. The patient was treated by marginal excision of the tumor. Histologic diagnosis was compatible with intramuscular myxoma.

Penile gangrene in a patient on renal dialysis: CT findings.

We presented a case of a 63-year-old man with type 2 diabetes mellitus and end-stage renal disease on hemodialysis. Precontrast CT images showed atrophy of kidneys bilaterally and calcification of the abdominal aorta, small branches of bilateral renal arteries and small arteries of the pelvis, including the internal pudendal artery and penile artery. Postcontrast CT scans revealed a nonenhancing glans penis with a clear margin relative to normal tissue. The CT findings were compatible with gangrenous penis and were confirmed by surgery and histology. Findings of CT images can help urologists to decide the cutting margin in planning surgery.

Inconspicuous visual field defect in anterior choroidal artery territory infarction.

We describe a patient with a right anterior choroidal artery territory infarction and an inconspicuous left visual defect. The anterior choroidal artery is a unique artery of the cerebral circulation. The occlusion of this artery can result in dysfunction of motor, sensory, and visual systems with only rare involvement of higher cortical function. Among symptoms reported, visual abnormalities are the most variable and the least common. However, the visual field abnormality may be overlooked and the incidence underestimated since some patients may not be aware of the problem until uncovered by formal visual field testing.

Tumoral calcinosis-like metastatic calcification in a patient on renal dialysis.

Tumoral calcinosis-like metastatic calcification in a patient with uremia on dialysis has rarely been reported in the radiological literatures. This report describes the radiographic, scintigraphic, ultrasound, and CT findings of this condition in a 54-year-old man who had a clinical history of renal dialysis for 6 years. Elevation of serum phosphate and parathyroid hormone levels was noted. Physical examination revealed a hard, movable, and tender mass over his left arm. Plain radiographs of the left shoulder showed an amorphous massive calcification in the upper arm. Scintigraphy showed increased tracer accumulation in the soft tissue of the proximal portion of the left arm and both thighs, where CT scan revealed multilocular, amorphous, calcified masses in these areas. Scintigraphy can help in screening multiple lesions, and CT scan may further help in identifying the extent of a localized lesion such as joint involvement. Ultrasound showed localized multiloculated fluid accumulation within hyperechoic masses and perifocal interstitial fluid collection, which can help to determine the activity of the lesion. Ultrasound findings of tumoral calcinosis have not been reported before.

Computed tomography angiography in detection and characterization of ruptured anterior cerebral artery aneurysms at uncommon location for emergent surgical clipping.

INTRODUCTION: Cerebral subarachnoid hemorrhage may result from rupture of saccular aneurysms at uncommon location [excluding the anterior communicating artery (ACOM)] of the anterior cerebral artery (ACA). The purpose of this study was to evaluate the usefulness of helical computed tomography angiography (CTA) in detection and characterization of intracranial aneurysms at such uncommon locations before emergent surgical clipping. MATERIALS AND METHODS: Between 1998 and 2003, records for 50 consecutive patients who underwent emergent surgical clipping for intracranial aneurysms were reviewed. Eighteen of these patients had aneurysms in the ACA. After those patients with unequivocal ACOM aneurysms were excluded, eight patients with eight aneurysms in an uncommon location of the ACA were recruited to this study. Plain computed tomography (CT) and CTA were performed in eight patients, and digital subtraction angiographies were done in three patients. Each aneurysm was evaluated for the detection, quantification, and characterization of the aneurysms with 2D multiplanar reformatted and 3D volume-rendering techniques. RESULTS: There were two small aneurysms arising from the A1 segment, one from the A2 segment, two at the junction of triplicated ACAs, two at the junction of A2 and A3 segments, and one at the junction of A2 and A3 segments of the azygos ACA. The average diameter of the aneurysmal sac was 4.44 mm (range, 2.7-7.0 mm), and the aneurysmal neck averaged 2.59 mm (range, 1.2-3.5 mm) in size. The smallest aneurysm measured 2.2x1.8x2.7 mm (neck, 1.2 mm) in the A1 segment of the left ACA. Three patients had intracerebral hematoma, seven had intraventricular hemorrhage, and three had acute hydrocephalus. CONCLUSION: Aneurysms in uncommon locations of ACAs exhibited characteristic features. Rupture of these aneurysms can cause intracerebral hematoma, intraventricular hemorrhage, and/or acute hydrocephalus. Noninvasive CTA can reliably detect and characterize intracranial aneurysms at such uncommon location for planning of emergent surgical intervention.

Predicting Mortality in Patients With "Malignant" Middle Cerebral Artery Infarction Using Susceptibility-Weighted Magnetic Resonance Imaging: Preliminary Findings.

To evaluate malignant middle cerebral artery (MCA) infarction (defined as space-occupying edema in more than 50% to 75% of the MCA territory) on magnetic resonance imaging (MRI) with susceptibility-weighted imaging (SWI) sequence and assess the usefulness of SWI findings, diffusion-weighted imaging (DWI) findings, and apparent diffusion coefficient (ADC) as predictors of clinical outcome.Data from 16 patients with large MCA infarction previously admitted to our institution between December 2009 and October 2012 were retrospectively collected and analyzed. Within 7 days after stroke onset, 1 neurologist and 1 neuroradiologist estimated the area of infarction on DWI/ADC and extent of prominent vessel sign (PVS) on SWI images using the Stroke Program Early MR Score (SPEMRS). The PVS on SWI was defined as a local prominence of hypointense vessels with either increased vessel number or diameter in the target area, when compared with the number or diameter of the contralateral MCA territory vessels.Six patients died and 10 survived. Although the DWI/ADC-SPEMRS and clinical profiles were similar between the nonsurvivor and survivor groups, SWI-SPEMRS was significantly lower in the nonsurvivor group (P < 0.001).The area of deoxygenation on SWI in patients with malignant MCA infarction can predict mortality. Lower SWI-SPEMRS is a potentially better predictor of poor outcome than lower DWI-SPEMRS. A larger prospective study is needed to clarify the role of SWI as a therapeutic guide in malignant MCA.

Parapharyngeal neuroglial heterotopia presenting as a growing single locular cyst: MR imaging findings.

Heterotopic brain presenting as a giant, growing, single locular cyst at the parapharyngeal space has not been reported before, to our knowledge. We present such a case, with MR imaging findings, in a 13-month-old girl. A well-demarcated giant cystic mass was noted in the left parapharyngeal space from the skull base to the submandibular region. Airway compression and deformity of the left mandible with subluxation of the temporomandibular joint were noted. The cyst contained a clear fluid that was isointense to CSF with all pulse sequences. Wall enhancement was noted on contrast-enhanced T1-weighted images. No connection to intracranial structures was noted. Histologic findings were compatible with neuroglial heterotopia.