Are the local blood oxygen level-dependent (BOLD) signals caused by neural stimulation response dependent on global BOLD signals induced by hypercapnia in the functional MR imaging experiment? Experiments of long-duration hypercapnia and multilevel carbon dioxide concentration

BACKGROUND AND PURPOSE

The relationship between the local blood oxygen level-dependent (BOLD) signals caused by neural stimulation (fBOLD) and the global BOLD signals induced by hypercapnia (hBOLD) has not been fully investigated. In this study, we examine whether fBOLD is modulated by hBOLD signals, by means of experiments using a relatively wide range of inhaled carbon dioxide (CO(2)) for a long duration of 5 minutes.

MATERIALS AND METHODS

Ten healthy volunteers were recruited, each undergoing 6 separate experiments by inhaling gas mixtures with different fractions of CO(2) (room air, 3%-7%). Each experiment contained 3 phases, prehypercapnic, hypercapnic, and posthypercapnic, during which boxcar visual stimulus was given. The local fBOLD signals were measured from areas showing activation patterns highly correlated with the visual stimulus paradigm, whereas the global hBOLD signals were measured from areas showing no visual activations. Percentage changes in fBOLD during transient-state hypercapnia and steady-state hypercapnia were both investigated in response to varying degrees of hypercapnic perturbations.

RESULTS

The hBOLD signals increased with increase of inhaled CO(2) fractions. The duration for the hBOLD signals to reach steady state prolonged with increase of inhaled CO(2) fractions. Normalized fBOLD ratio was inversely related to the inhaled CO(2) during steady-state hypercapnia but showed positive association with hBOLD during transient-state hypercapnia.

CONCLUSION

Our study concludes that the steady-state fBOLD signal intensity is dependent on and inversely related to the hBOLD signals. Previous reports documenting independent and additive relationships between hBOLD and fBOLD may likely be due to transient-state observations.

Imaging findings of intradiaphragmatic bronchogenic cyst: a case report

Isolated intradiaphragmatic bronchogenic cysts are extremely rare. Here, we report a case of intradiaphragmatic bronchogenic cyst with calcifications in a 34-year-old man presenting with no clinical symptoms. Imaging studies of the chest, including chest roentgenogram and computerized tomography (CT), revealed a left posterior mediastinal mass that abutted onto the left diaphragmatic crus with multiple calcifications and showed no enhancement after contrast administration on CT. The patient underwent surgical resection of the mass. Intradiaphragmatic bronchogenic cyst with calcifications was diagnosed by pathology. The patient was discharged 10 days after the operation, and no complication was found 3 months later at follow-up.

Primitive neuroectodermal tumor of the kidney associated with Budd-Chiari syndrome in a 17-year-old girl

Renal primitive neuroectodermal tumor (PNET) is a rare and highly malignant neoplasm of the kidney. We report the case of a 17-year-old girl with renal PNET that was complicated by Budd-Chiari syndrome. She was admitted due to abrupt left flank pain and gross hematuria. Abdominal sonography and computerized tomography (CT) disclosed a large hemorrhagic left renal mass and thrombus in the inferior vena cava (IVC). Left radical nephrectomy was performed and renal PNET with tumor rupture and tumor invasion into the IVC was diagnosed based on operative findings and histologic features. Tumor cells were positive for neuronspecific enolase, chromogranin-A, and vimentin but negative for cytokeratin, leukocyte common antigen, CD3, and CD20. The thrombus in the IVC extended into the right atrium and caused obstruction of the right and middle hepatic venous outflow, which was evident on follow-up CT scan 5 months later. The patient died due to hepatic failure and progressive cardiovascular compromise 6 months after surgery. This case demonstrates that renal PNET can be life threatening when the tumor thrombus extends into the IVC and causes hepatic outflow obstruction.

Synovial chondroma of the ankle in a young child after recent trauma: CT and MR features

We report a case of synovial chondroma of the left ankle in an 11-year-old boy presenting with soft tissue swelling after recent trauma. The noncalcified or nonossified intraarticular chondroma arising from metaplastic synovium has characteristic imaging appearance on computed tomography (CT) and magnetic resonance imaging (MRI). A lobulated mass of fluid-like density and signal intensity along with internal septa are characteristic features on CT and MRI. The knowledge of CT and MRI features of noncalcified or nonossified synovial chondroma is important to distinguish from the simple or complicated effusion, hemarthrosis, or other synovial process.

Subglottic hemangioma associated with cutaneous and cerebellar hemangiomas detected by MRI: report of one case

Subglottic hemangioma (SGH) is a benign neoplasm that may cause severe and life-threatening respiratory obstruction in infants. However, patients usually present with inspiratory stridor in the first few months of life and may be mistakenly diagnosed as recurrent or persistent croup. Definitive diagnosis is made by image studies, endoscopic examination and biopsy or all. We report a 2-month-old female infant of SGH with initial clinical manifestations of dyspnea and inspiratory stridor co-existing with cutaneous and cerebellar hemangiomas. Clinicians must be alert the possibility of SGH when associated with cutaneous hemangioma. This patient has received oral steroid treatment for more than two months with improvement of the airway obstruction. Although purplish patch lesions over left side of face, eyelid, cheek, and peri-oral regions regressed, the size of the SGH on the followed MRI was slightly enlarged. The diagnosis and various treatments of SGH are discussed and reviewed in this paper.

Primary hemangiopericytoma of the tibia: MR and angiographic correlation

The Magnetic Resonance Imaging (MRI) appearances of primary osseous hemangiopericytoma (HPC) have been rarely described. We report on a 46-year-old Chinese man with primary osseous HPC of the right tibia. The characteristic vascular distribution of this tumor, presenting with a "spoke-wheel" appearance on MR images and with angiographic correlation, is described. Although not pathognomonic, this MR appearance may be an important finding in suggesting the diagnosis of osseous HPC.