Flat-panel volume computed tomography (CT) systems have an innovative design that allows coverage of a large volume per rotation, fluoroscopic and dynamic imaging, and high spatial resolution that permits visualization of complex human anatomy such as fine temporal bone structures and trabecular bone architecture. In simple terms, flat-panel volume CT scanners can be thought of as conventional multidetector CT scanners in which the detector rows have been replaced by an area detector. The flat-panel detector has wide z-axis coverage that enables imaging of entire organs in one axial acquisition. Its fluoroscopic and angiographic capabilities are useful for intraoperative and vascular applications. Furthermore, the high-volume coverage and continuous rotation of the detector may enable depiction of dynamic processes such as coronary blood flow and whole-brain perfusion. Other applications in which flat-panel volume CT may play a role include small-animal imaging, nondestructive testing in animal survival surgeries, and tissue-engineering experiments. Such versatility has led some to predict that flat-panel volume CT will gain importance in interventional and intraoperative applications, especially in specialties such as cardiac imaging, interventional neuroradiology, orthopedics, and otolaryngology. However, the contrast resolution of flat-panel volume CT is slightly inferior to that of multidetector CT, a higher radiation dose is needed to achieve a comparable signal-to-noise ratio, and a slower scintillator results in a longer scanning time.

We have demonstrated promising results with a prospective protocol of CTA in place of DSA as the only diagnostic and pretreatment planning study for patients with ruptured and unruptured cerebral aneurysms. It seems safe and effective to make decisions regarding treatment on the basis of CTA, without performing DSA, in the majority of patients with ruptured and unruptured cerebral aneurysms.

Purpose:To examine trabecular microarchitecture with high-resolution flat-panel volume computed tomography (CT) and bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) in adolescent girls with anorexia nervosa (AN) and to compare these results with those in normal-weight control subjects. Materials and Methods:The study was approved by the institutional review board and complied with HIPAA guidelines. Informed consent was obtained. Twenty adolescent girls, 10 with mild AN (mean age, 15.9 years; range, 13-18 years) and 10 ageand sex-matched normal-weight control subjects (mean age, 15.9 years; range, 12-18 years) underwent flat-panel volume CT of distal radius to determine apparent trabecular bone volume fraction (BV/TV), apparent trabecular number (TbN), apparent trabecular thickness (TbTh), and apparent trabecular separation (TbSp). All subjects underwent DXA of spine, hip, and whole body to determine BMD and body composition. The means and standard deviations (SDs) of structure parameters were calculated for AN and control groups. Groups were compared (Student t test). Linear regression analysis was performed. Results:AN subjects compared with control subjects, respectively, showed significantly lower mean values for BV/TV (0.37% Ϯ 0.05 [SD] vs 0.46% Ϯ 0.03, P ϭ .0002) and TbTh (0.31 mm Ϯ 0.03 vs 0.39 mm Ϯ 0.03, P Ͻ .0001) and higher mean values for TbSp (0.54 mm Ϯ 0.13 vs 0.44 mm Ϯ 0.04, P ϭ .02). TbN was lower in AN subjects than in control subjects, but the difference was not significant (1.17 mm Ϫ3 Ϯ 0.15 vs 1.22 mm Ϫ3 Ϯ 0.07, P ϭ .43). There was no significant difference in BMD between AN and control subjects. BMD parameters showed positive correlation with BV/TV and TbTh in the control group (r ϭ 0.55-0.84, P ϭ .05-.01) but not in AN patients. Conclusion:Flat-panel volume CT is effective in evaluation of trabecular structure in adolescent girls with AN and demonstrates that bone structure is abnormal in these patients compared with that in normal-weight control subjects despite normal BMD. RSNA, 2008 Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, use the Radiology Reprints form at the end of this article. Low bone mineral density (BMD) is a serious complication of anorexia nervosa (AN) in adults and adolescents (1,2). Decreased bone mass occurs in multiple skeletal sites and is associated with a sevenfold increased fracture risk that may persist despite recovery (3,4). The onset of AN during the adolescent years is of particular concern because this is a crucial time for bone mass accrual toward achievement of peak bone mass. Deficits in the normal rate of bone mass accrual during this period can result in low peak bone mass and an increased risk of fractures in adult life (2,5). Dual-energy x-ray absorptiometry (DXA) is commonly used for the assessment of BMD; however, it is highly influenced by body size (6), which provides a diagnostic challenge in children with AN, because prolon...

Reflectance confocal microscopy (RCM) allows non-invasive visualization of human skin in vivo. It has been used to describe the histopathological features of acute contact dermatitis (CD). This work was designed to investigate the kinetics of both allergic and irritant CD (ACD and ICD) in vivo. Eighteen subjects with a prior diagnosis of ACD were patch tested with the specific allergen sodium lauryl sulfate as an irritant, and appropriate controls. RCM, transepidermal water loss (TEWL), and fluorescence excitation spectroscopy (FES) were performed at several time points within 2 wk after patch removal. After removal of the Finn chambers at 48 h, superficial epidermal changes, primarily involving the stratum corneum, and increased epidermal thickness were mainly present in ICD. ACD, on the other hand, showed microvesicle formation peaking at 96 h following patch removal. Both ACD and ICD showed exocytosis and similar degrees of spongiosis on RCM. TEWL and FES demonstrated a significant difference between ACD and ICD. RCM, TEWL, and FES are valuable non-invasive tools to quantitatively study the kinetics of the pathophysiology of acute CD reactions in vivo and monitor the changes at a cellular level.