Diffusivity measurements differentiate benign from malignant lesions in patients with peripheral neuropathy or plexopathy

BACKGROUND AND PURPOSE

Peripheral nerve disorders caused by benign and malignant primary nerve sheath tumors, infiltration or compression of nerves by metastatic disease, and postradiation neuritis demonstrate overlapping features on conventional MR imaging but require vastly different therapeutic approaches. We characterize and compare diffusivities of peripheral nerve lesions in patients undergoing MR neurography for peripheral neuropathy or brachial or lumbosacral plexopathy.

MATERIALS AND METHODS

Twenty-three patients, referred for MR neurography at our institution between 2003 and 2009 for a peripheral mononeuropathy or brachial or lumbosacral plexopathy and whose examinations included DWI, received a definitive diagnosis, based on biopsy results or clinical and imaging follow-up, for a masslike or infiltrative peripheral nerve or plexus lesion suspicious for tumor. Mean ADC values were determined within each lesion and compared across 3 groups (benign lesions, malignant lesions, and postradiation changes).

RESULTS

Both ANOVA and Kruskal-Wallis tests demonstrated a statistically significant difference in ADC values across the 3 groups (P = .000023, P = .00056, respectively). Post hoc pair-wise comparisons showed that the ADC within malignant tumors differed significantly from that within benign tumors and postradiation changes. ADC within benign tumors and postradiation changes did not differ significantly from each other.

CONCLUSIONS

DWI may be highly effective for the differentiation of benign from malignant peripheral nerve masslike or infiltrative lesions.

Diffusion tensor imaging for outcome prediction in mild traumatic brain injury: a TRACK-TBI study

We evaluated 3T diffusion tensor imaging (DTI) for white matter injury in 76 adult mild traumatic brain injury (mTBI) patients at the semiacute stage (11.2±3.3 days), employing both whole-brain voxel-wise and region-of-interest (ROI) approaches. The subgroup of 32 patients with any traumatic intracranial lesion on either day-of-injury computed tomography (CT) or semiacute magnetic resonance imaging (MRI) demonstrated reduced fractional anisotropy (FA) in numerous white matter tracts, compared to 50 control subjects. In contrast, 44 CT/MRI-negative mTBI patients demonstrated no significant difference in any DTI parameter, compared to controls. To determine the clinical relevance of DTI, we evaluated correlations between 3- and 6-month outcome and imaging, demographic/socioeconomic, and clinical predictors. Statistically significant univariable predictors of 3-month Glasgow Outcome Scale-Extended (GOS-E) included MRI evidence for contusion (odds ratio [OR] 4.9 per unit decrease in GOS-E; p=0.01), ≥1 ROI with severely reduced FA (OR, 3.9; p=0.005), neuropsychiatric history (OR, 3.3; p=0.02), age (OR, 1.07/year; p=0.002), and years of education (OR, 0.79/year; p=0.01). Significant predictors of 6-month GOS-E included ≥1 ROI with severely reduced FA (OR, 2.7; p=0.048), neuropsychiatric history (OR, 3.7; p=0.01), and years of education (OR, 0.82/year; p=0.03). For the subset of 37 patients lacking neuropsychiatric and substance abuse history, MRI surpassed all other predictors for both 3- and 6-month outcome prediction. This is the first study to compare DTI in individual mTBI patients to conventional imaging, clinical, and demographic/socioeconomic characteristics for outcome prediction. DTI demonstrated utility in an inclusive group of patients with heterogeneous backgrounds, as well as in a subset of patients without neuropsychiatric or substance abuse history.

Calvarial fracture patterns on CT imaging predict risk of a delayed epidural hematoma following decompressive craniectomy for traumatic brain injury

BACKGROUND AND PURPOSE

The development of a delayed epidural hematoma as a result of decompressive craniectomy represents an urgent and potentially lethal complication in traumatic brain injury. The goal of this study was to determine the incidence of delayed epidural hematoma and whether patterns of skull fractures on the preoperative CT scan could predict risk of a delayed epidural hematoma.

MATERIALS AND METHODS

We retrospectively evaluated medical records and imaging studies for patients with acute traumatic brain injury who underwent a decompressive craniectomy during a 9-year period. We compared patterns of skull fractures contralateral to the side of the craniectomy with the occurrence of a postoperative delayed epidural hematoma.

RESULTS

In a series of 203 patients undergoing decompressive craniectomy for acute traumatic brain injury, the incidence of a delayed epidural hematoma complication was 6% (12 of 203). All 12 patients who developed a delayed epidural hematoma had a contralateral calvarial fracture on preoperative CT at the site where the delayed epidural hematoma subsequently formed. A contralateral calvarial fracture has perfect sensitivity (100%) for subsequent development of delayed epidural hematoma in our study population. Moreover, a contralateral calvarial fracture involving 2 or more bone plates had an especially high diagnostic odds ratio of 41 for delayed epidural hematoma.

CONCLUSIONS

Recognition of skull fracture patterns associated with delayed epidural hematoma following decompressive craniectomy may reduce morbidity and mortality by prompting early postoperative intervention in high-risk situations.

Detection of micrometastases of squamous cell carcinoma tumor cells in muscle tissue

The aim of this study was to evaluate microarray technology in the detection of micrometastases of head and neck squamous cell carcinoma (HNSCC) in muscle tissue. Three hundred SCCVII tumor cells were injected intramuscularly into the right flank of ten C3H/Km mice. One week later, the animals were euthanized and the muscle tissue was taken out. Histology (H&E staining), microarray and reverse transcriptase polymerase chain reaction analysis (RT-PCR) of the tissue was performed. Histology showed a few tumor cells between the muscle fibers. Microarray technology showed the different gene expression pattern of the muscle tissue with micrometastases in comparison to normal muscle tissue. Only genes with a fold change difference of 10 or greater were considered. Gene expression analysis revealed changes in the expression levels of 91 genes of micrometastases in muscle tissue. RT-PCR confirmed gene up-regulation. Significant differences in gene expression between micrometastases in muscle tissue and pure muscle tissue were found. The genes found to be up-regulated could be used to detect micrometastases in muscle tissue.

The impact of previous traumatic brain injury on health and functioning: a TRACK-TBI study

The idea that multiple traumatic brain injury (TBI) can have a cumulative detrimental effect on functioning is widely accepted. Most research supporting this idea comes from athlete samples, and it is not known whether remote history of previous TBI affects functioning after subsequent TBI in community-based samples. This study investigates whether a previous history of TBI with loss of consciousness (LOC) is associated with worse health and functioning in a sample of individuals who require emergency department care for current TBI. Twenty-three percent of the 586 individuals with current TBI in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury study reported having sustained a previous TBI with LOC. Individuals with previous TBI were more likely to be unemployed (χ(2)=17.86; p=0.000), report a variety of chronic medical and psychiatric conditions (4.75≤χ(2)≥24.16; p<0.05), and report substance use (16.35≤χ(2)≥27.57; p<0.01) before the acute injury, compared to those with no previous TBI history. Those with a previous TBI had less-severe acute injuries, but experienced worse outcomes at 6-month follow-up. Results of a series of regression analyses controlling for demographics and acute injury severity indicated that individuals with previous TBI reported more mood symptoms, more postconcussive symptoms, lower life satisfaction, and had slower processing speed and poorer verbal learning, compared to those with no previous TBI history. These findings suggest that history of TBI with LOC may have important implications for health and psychological functioning after TBI in community-based samples.

Acute biomarkers of traumatic brain injury: relationship between plasma levels of ubiquitin C-terminal hydrolase-L1 and glial fibrillary acidic protein

Biomarkers are important for accurate diagnosis of complex disorders such as traumatic brain injury (TBI). For a complex and multifaceted condition such as TBI, it is likely that a single biomarker will not reflect the full spectrum of the response of brain tissue to injury. Ubiquitin C-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) are among of the most widely studied biomarkers for TBI. Because UCH-L1 and GFAP measure distinct molecular events, we hypothesized that analysis of both biomarkers would be superior to analysis of each alone for the diagnosis and prognosis of TBI. Serum levels of UCH-L1 and GFAP were measured in a cohort of 206 patients with TBI enrolled in a multicenter observational study (Transforming Research and Clinical Knowledge in Traumatic Brain Injury [TRACK-TBI]). Levels of the two biomarkers were weakly correlated to each other (r=0.364). Each biomarker in isolation had good sensitivity and sensitivity for discriminating between TBI patients and healthy controls (area under the curve [AUC] 0.87 and 0.91 for UCH-L1 and GFAP, respectively). When biomarkers were combined, superior sensitivity and specificity for diagnosing TBI was obtained (AUC 0.94). Both biomarkers discriminated between TBI patients with intracranial lesions on CT scan and those without such lesions, but GFAP measures were significantly more sensitive and specific (AUC 0.88 vs. 0.71 for UCH-L1). For association with outcome 3 months after injury, neither biomarker had adequate sensitivity and specificity (AUC 0.65-0.74, for GFAP, and 0.59-0.80 for UCH-L1, depending upon Glasgow Outcome Scale Extended [GOS-E] threshold used). Our results support a role for multiple biomarker measurements in TBI research. ( ClinicalTrials.gov Identifier NCT01565551).

Transforming research and clinical knowledge in traumatic brain injury pilot: multicenter implementation of the common data elements for traumatic brain injury

Traumatic brain injury (TBI) is among the leading causes of death and disability worldwide, with enormous negative social and economic impacts. The heterogeneity of TBI combined with the lack of precise outcome measures have been central to the discouraging results from clinical trials. Current approaches to the characterization of disease severity and outcome have not changed in more than three decades. This prospective multicenter observational pilot study aimed to validate the feasibility of implementing the TBI Common Data Elements (TBI-CDEs). A total of 650 subjects who underwent computed tomography (CT) scans in the emergency department within 24 h of injury were enrolled at three level I trauma centers and one rehabilitation center. The TBI-CDE components collected included: 1) demographic, social and clinical data; 2) biospecimens from blood drawn for genetic and proteomic biomarker analyses; 3) neuroimaging studies at 2 weeks using 3T magnetic resonance imaging (MRI); and 4) outcome assessments at 3 and 6 months. We describe how the infrastructure was established for building data repositories for clinical data, plasma biomarkers, genetics, neuroimaging, and multidimensional outcome measures to create a high quality and accessible information commons for TBI research. Risk factors for poor follow-up, TBI-CDE limitations, and implementation strategies are described. Having demonstrated the feasibility of implementing the TBI-CDEs through successful recruitment and multidimensional data collection, we aim to expand to additional study sites. Furthermore, interested researchers will be provided early access to the Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) data set for collaborative opportunities to more precisely characterize TBI and improve the design of future clinical treatment trials. (ClinicalTrials.gov Identifier NCT01565551.).

GFAP-BDP as an acute diagnostic marker in traumatic brain injury: results from the prospective transforming research and clinical knowledge in traumatic brain injury study

Reliable diagnosis of traumatic brain injury (TBI) is a major public health need. Glial fibrillary acidic protein (GFAP) is expressed in the central nervous system, and breakdown products (GFAP-BDP) are released following parenchymal brain injury. Here, we evaluate the diagnostic accuracy of elevated levels of plasma GFAP-BDP in TBI. Participants were identified as part of the prospective Transforming Research And Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Study. Acute plasma samples (<24 h post-injury) were collected from patients presenting with brain injury who had CT imaging. The ability of GFAP-BDP level to discriminate patients with demonstrable traumatic lesions on CT, and with failure to return to pre-injury baseline at 6 months, was evaluated by the area under the receiver operating characteristic curve (AUC). Of the 215 patients included for analysis, 83% had mild, 4% had moderate, and 13% had severe TBI; 54% had acute traumatic lesions on CT. The ability of GFAP-BDP level to discriminate patients with traumatic lesions on CT as evaluated by AUC was 0.88 (95% confidence interval [CI], 0.84-0.93). The optimal cutoff of 0.68 ng/mL for plasma GFAP-BDP level was associated with a 21.61 odds ratio for traumatic findings on head CT. Discriminatory ability of unfavorable 6 month outcome was lower, AUC 0.65 (95% CI, 0.55-0.74), with a 2.07 odds ratio. GFAP-BDP levels reliably distinguish the presence and severity of CT scan findings in TBI patients. Although these findings confirm and extend prior studies, a larger prospective trial is still needed to validate the use of GFAP-BDP as a routine diagnostic biomarker for patient care and clinical research. The term "mild" continues to be a misnomer for this patient population, and underscores the need for evolving classification strategies for TBI targeted therapy. (ClinicalTrials.gov number NCT01565551; NIH Grant 1RC2 NS069409).

Magnetic resonance imaging improves 3-month outcome prediction in mild traumatic brain injury

OBJECTIVE

To determine the clinical relevance, if any, of traumatic intracranial findings on early head computed tomography (CT) and brain magnetic resonance imaging (MRI) to 3-month outcome in mild traumatic brain injury (MTBI).

METHODS

One hundred thirty-five MTBI patients evaluated for acute head injury in emergency departments of 3 LEVEL I trauma centers were enrolled prospectively. In addition to admission head CT, early brain MRI was performed 12 ± 3.9 days after injury. Univariate and multivariate logistic regression were used to assess for demographic, clinical, socioeconomic, CT, and MRI features that were predictive of Extended Glasgow Outcome Scale (GOS-E) at 3 months postinjury.

RESULTS

Twenty-seven percent of MTBI patients with normal admission head CT had abnormal early brain MRI. CT evidence of subarachnoid hemorrhage was associated with a multivariate odds ratio of 3.5 (p = 0.01) for poorer 3-month outcome, after adjusting for demographic, clinical, and socioeconomic factors. One or more brain contusions on MRI, and ≥4 foci of hemorrhagic axonal injury on MRI, were each independently associated with poorer 3-month outcome, with multivariate odds ratios of 4.5 (p = 0.01) and 3.2 (p = 0.03), respectively, after adjusting for head CT findings and demographic, clinical, and socioeconomic factors.

INTERPRETATION

In this prospective multicenter observational study, the clinical relevance of abnormal findings on early brain imaging after MTBI is demonstrated. The addition of early CT and MRI markers to a prognostic model based on previously known demographic, clinical, and socioeconomic predictors resulted in a >2-fold increase in the explained variance in 3-month GOS-E.

Quantitative CT improves outcome prediction in acute traumatic brain injury

The admission noncontrast head computed tomography (CT) scan has been demonstrated to be one of several key early clinical and imaging features in the challenging problem of prediction of long-term outcome after acute traumatic brain injury (TBI). In this study, we employ two novel approaches to the problem of imaging classification and outcome prediction in acute TBI. First, we employ the novel technique of quantitative CT (qCT) image analysis to provide more objective, reproducible measures of the abnormal features of the admission head CT in acute TBI. We show that the incorporation of quantitative, rather than qualitative, CT features results in a significant improvement in prediction of the 6-month Extended Glasgow Outcome Scale (GOS-E) score over a wide spectrum of injury severity. Second, we employ principal components analysis (PCA) to demonstrate the interdependence of certain predictive variables. Relatively few prior studies of outcome prediction in acute TBI have used a multivariate approach that explicitly takes into account the potential covariance among clinical and CT predictive variables. We demonstrate that several predictors, including midline shift, cistern effacement, subdural hematoma volume, and Glasgow Coma Scale (GCS) score are related to one another. Rather than being independent features, their importance may be related to their status as surrogate measures of a more fundamental underlying clinical feature, such as the severity of intracranial mass effect. We believe that objective computational tools and data-driven analytical methods hold great promise for neurotrauma research, and may ultimately have a role in image analysis for clinical care.

Gene expression analysis of SCC tumor cells in muscle tissue

The purpose of this study was to evaluate microarray technology of HNSCC cells in muscle tissue. 200 SCCVII tumor cells were injected intramuscularly into the right flank of ten C3H/Km mice each. One week later the animals were killed and the tissue taken out. Histology (H&E staining) and microarray of the tissue were performed. Histology showed a few tumor cells between the muscle fibers. Microarray technology showed different gene expression pattern of the muscle tissue with SCCVII cells in comparison with normal muscle tissue. Only those genes showing a fold change difference of 5 or higher were considered. Gene expression analysis revealed changes in the expression levels of SCCVII cells in muscle tissue in 220 genes. Significant gene expression differences between SCCVII cells in muscle tissue and pure muscle tissue could be seen.

Effect of continuous high intensity focused ultrasound in a squamous cell carcinoma tumor model compared to muscle tissue evaluated by MRI, histology, and gene expression

The purpose of this study was to investigate the effect of the continuous mode of high intensity focused ultrasound (HIFU) in a mouse head and neck cancer model (SCCVII) compared to muscle tissue. HIFU was applied to SCCVII tumors and to muscle tissue in C3H/Km mice using a dual ultrasound system (imaging 6 MHz/therapeutic 1 MHz). A continuous HIFU mode (total time 20 sec, intensity 6730.6 W/cm(2)) was applied. Three hours after HIFU treatment pre- and post-contrast T1-wt, T2-wt images, and a diffusion-wt STEAM sequence were obtained. After MR imaging, the animals were euthenized and the treated tumor and muscle tissue was taken out for histology and functional genomic analysis. T2 images showed increased signal intensity, post-contrast T1 showed a decreased contrast uptake in the central parts in the tumor tissue as well as in the muscle tissue. In addition a significant higher diffusion coefficient was found in both tissue types. Histological evaluation (H&E, Immunohistochemistry) of the tumors and the muscle tissue revealed areas of significant necrosis. In the tumor tissue 23 genes were up-regulated (> 2 fold change) and 4 genes were down-regulated (< -2 fold change). In the muscle tissue 29 genes were up-regulated and 17 genes down-regulated. Thirteen genes were up-regulated in both tissue types, 8 genes only in the SCCVII tissue, and 11 genes only in the muscle tissue. The use of HIFU treatment on tumor and muscle tissue results in dramatic changes in gene expression. The expression of some genes are tissue specific, the expression of other genes are independent of the tissue type.

Mechanic effect of pulsed focused ultrasound in tumor and muscle tissue evaluated by MRI, histology, and microarray analysis

The purpose of this study was to investigate the effect of pulsed high-intensity focused ultrasound (HIFU) to tumor and muscle tissue. Pulsed HIFU was applied to tumor and muscle tissue in C3H/Km mice. Three hours after HIFU treatment pre- and post-contrast T1-wt, T2-wt images and a diffusion-wt STEAM-sequence were obtained. After MR imaging, the animals were euthenized and the treated tumor and muscle was taken out for histology and functional genomic analysis. In the tumor tissue a slight increase of the diffusion coefficient could be found. In the muscle tissue T2 images showed increased signal intensity and post-contrast T1 showed a decreased contrast uptake in the center and a severe contrast uptake in the surrounding muscle tissue. A significant increase of the diffusion coefficient was found. Gene expression analysis revealed profound changes in the expression levels of 29 genes being up-regulated and 3 genes being down-regulated in the muscle tissue and 31 genes being up-regulated and 15 genes being down-regulated in the SCCVII tumor tissue. Seven genes were up-regulated in both tissue types. The highest up-regulated gene in the tumor and muscle tissue encoded for Mouse histone H2A.1 gene (FC=13.2±20.6) and Apolipoprotein E (FC=12.8±27.4) respectively MHC class III (FC=83.7±67.4) and hsp70 (FC=75.3±85.0). Immunoblot confirmed the presence of HSP70 protein in the muscle tissue. Pulsed HIFU treatment on tumor and muscle tissue results in dramatic changes in gene expression, indicating that the effect of pulsed HIFU is in some regard dependent and also independent of the tissue type.

Computer-aided assessment of head computed tomography (CT) studies in patients with suspected traumatic brain injury

In this study, we sought to determine the accuracy of a computer algorithm that automatically assesses head computed tomography (CT) studies in patients with suspected traumatic brain injury (TBI) for features of intracranial hemorrhage and mass effect, employing a neuroradiologist's interpretation as the gold standard. To this end, we designed a suite of computer algorithms that evaluates in a fully automated fashion the presence of intracranial blood and/or mass effect based on the following CT findings: (1) presence or absence of a subdural or epidural hematoma, (2) presence or absence of subarachnoid hemorrhage, (3) presence or absence of an intraparenchymal hematoma, (4) presence or absence of clinically significant midline shift (>or=5 mm), and (5) normal, partly effaced, or completely effaced basal cisterns. The algorithm displays abnormal findings as color overlays on the original head CT images, and calculates the volume of each type of blood collection, the midline shift, and the volume of the basal cisterns, based on the above-described features. Thresholds and parameters yielding optimal accuracy of the computer algorithm were determined using a development sample of 33 selected, nonconsecutive patients. The software was then applied to a validation sample of 250 consecutive patients evaluated for suspicion of acute TBI at our institution in 2006-2007. Software detection of the presence of at least one noncontrast CT (NCT) feature of acute TBI demonstrated high sensitivity of 98% and high negative predictive value (NPV) of 99%. There was actually only one false negative case, where a very subtle subdural hematoma, extending exclusively along the falx, was diagnosed by the neuroradiologist, while the case was considered as normal by the computer algorithm. The software was excellent at detecting the presence of mass effect and intracranial hemorrhage, but showed some disagreements with the neuroradiologist in quantifying the degree of mass effect and characterizing the type of intracranial hemorrhage. In summary, we have developed a fully automated computer algorithm that demonstrated excellent sensitivity for acute intracranial hemorrhage and clinically significant midline shift, while maintaining intermediate specificity. Further studies are required to evaluate the potential favorable impact of this software on facilitating workflow and improving diagnostic accuracy when used as a screening aid by physicians with different levels of experience.

Comparison of continuous vs. pulsed focused ultrasound in treated muscle tissue as evaluated by magnetic resonance imaging, histological analysis, and microarray analysis

The purpose of this study was to investigate the effect of different application modes of high intensity focused ultrasound (HIFU) to muscle tissue. HIFU was applied to muscle tissue of the flank in C3H/Km mice. Two dose regimes were investigated, a continuous HIFU and a short-pulsed HIFU mode. Three hours after HIFU treatment pre- and post-contrast T1-weighted, T2-weighted images and a diffusion-weighted STEAM sequence were obtained. After MR imaging, the animals were euthanized and the treated, and the non-treated tissue was taken out for histology and functional genomic analysis. T2 images showed increased signal intensity and post-contrast T1 showed a decreased contrast uptake in the central parts throughout the tissue of both HIFU modes. A significantly higher diffusion coefficient was found in the muscle tissue treated with continuous wave focused ultrasound. Gene expression analysis revealed profound changes of 54 genes. For most of the analyzed genes higher expression was found after treatment with the short-pulse mode. The highest up-regulated genes encoded for the MHC class III (FC approximately 84), HSP 70 (FC approximately 75) and FBJ osteosarcoma related oncogene (FC approximately 21). Immunohistology and the immunoblot analysis confirmed the presence of HSP70 protein in both applied HIFU modes. The use of HIFU treatment on muscle tissue results in dramatic changes in gene expression; however, the same genes are up-regulated after the application of continuous or pulsed HIFU, indicating that the tissue reaction is independent of the type of tissue damage.

Gene Expression Profiles, Histologic Analysis, and Imaging of Squamous Cell Carcinoma Model Treated with Focused Ultrasound Beams

OBJECTIVE

The purpose of our study was to evaluate the effect of short-pulse high-intensity focused ultrasound (HIFU) on inducing cell death in a head and neck cancer model (SCCVII [squamous cell carcinoma]) compared with continuous HIFU to get a better understanding of the biologic changes caused by HIFU therapy.

MATERIALS AND METHODS

HIFU was applied to 12 SCCVII tumors in C3H/Km mice using a dual sonography system (imaging, 6 MHz; therapeutic, 1 MHz). A continuous HIFU mode (total time, 20 seconds; intensity, 6,730.6 W/cm2) and a short-pulse HIFU mode (frequency, 0.5 Hz; pulse duration, 50 milliseconds; total time, 16.5 minutes; intensity, 134.4 W/cm2) was applied. Three hours later, MR images were obtained on a 1.5-T scanner. After imaging, the treated and untreated control tumor tissue samples were taken out for histology and oligonucleotide microarray analysis.

RESULTS

Prominent changes were observed in the MR images in the continuous HIFU mode, whereas the short-pulse HIFU mode showed no discernible changes. Histology (H and E, TUNEL [terminal deoxynucleotidyl transferase-mediated dUTP {deoxyuridine triphosphate} nick-end labeling], and immunohistochemistry) of the tumors treated with the continuous HIFU mode revealed areas of significant necrosis. In the short-pulse HIFU mode, the H and E staining showed multifocal areas of coagulation necrosis. TUNEL staining showed a high apoptotic index in both modes. Gene expression analysis revealed profound differences. In the continuous HIFU mode, 23 genes were up-regulated (> twofold change) and five genes were down-regulated (< twofold change), and in the short-pulse HIFU mode, 32 different genes were up-regulated and 16 genes were down-regulated.

CONCLUSION

Genomic analysis might be included when investigating tissue changes after interventional therapy because it offers the potential to find molecular targets for imaging and therapeutic applications.

Delivery of systemic chemotherapeutic agent to tumors by using focused ultrasound: study in a murine model

PURPOSE

To quantitatively determine the delivery of systemic liposomal doxorubicin to tumors treated with pulsed high-intensity focused ultrasound and to study the mechanism underlying this delivery in a murine model.

MATERIALS AND METHODS

All animal work was performed in compliance with guidelines and approval of institutional animal care committee. C3H mice received subcutaneous injections in the flank of a cell suspension of SCC7, a murine squamous cell carcinoma cell line; mice (n = 32) in drug delivery study received unilateral injections, whereas mice (n = 10) in mechanistic study received bilateral injections. Tumors were treated when they reached 1 cm(3) in volume. In the drug delivery study, doxorubicin hydrochloride liposomes were injected into the tail vein: Mice received therapy with doxorubicin injections and high-intensity focused ultrasound, doxorubicin injections alone, or neither form of therapy (controls). Tumors were removed, and the doxorubicin content was assayed with fluorescent spectrophotometry. In the mechanistic study, all mice received an injection of 500-kDa dextran-fluorescein isothyocyanate into the tail vein, and half of them were exposed to high-intensity focused ultrasound prior to injection. Contralateral tumors served as controls for each group. Extravasation of dextran-fluorescein isothyocyanate was observed by using in vivo confocal microscopy.

RESULTS

Mean doxorubicin concentration in tumors treated with pulsed high-intensity focused ultrasound was 9.4 microg . g(-1) +/- 2.1 (standard deviation), and it was significantly higher (124% [9.4 microg . g(-1)/4.2 microg . g(-1)]) than in those that were not treated with high-intensity focused ultrasound (4.2 microg . g(-1) +/- 0.95) (P < .001, unpaired two-tailed Student t test). Extravasation of dextran-fluorescein isothyocyanate was observed in the vasculature of tumors treated with high-intensity focused ultrasound but not in that of untreated tumors.

CONCLUSION

Pulsed high-intensity focused ultrasound is an effective method of targeting systemic drug delivery to tumor tissue. Potential mechanisms for producing the observed enhancement are discussed.

Unilateral putaminal CT, MR, and diffusion abnormalities secondary to nonketotic hyperglycemia in the setting of acute neurologic symptoms mimicking stroke

A 75-year-old Asian man presented with two episodes of chorea associated with nonketotic hyperglycemia. His chorea rapidly resolved after restitution of a normal serum glucose level, although an MR image obtained at the time of acute symptoms demonstrated high signal intensity on T1-weighted images, low signal intensity on T2-weighted images, and restricted diffusion, all involving the left putamen. A CT scan obtained 1 month later demonstrated faint hyperattenuation of the involved putamen. The reported pathophysiologic considerations for these imaging features are reviewed, and an original explanation is proposed.

Virtual endoscopy using perspective volume-rendered three-dimensional sonographic data: technique and clinical applications

OBJECTIVE

We present a technique for obtaining three-dimensional external and virtual endoscopy views of organs using perspective volume-rendered gray-scale and Doppler sonographic data, and we explore potential clinical applications in the carotid artery, the female pelvis, and the bladder.

CONCLUSION

Using the proposed methods, radiologists will find it possible to create virtual endoscopy and external perspective views using sonographic data. The technique works well for revealing the interior of fluid-filled structures and cavities. However, expected improvements in computer performance and integration with existing sonographic equipment will be necessary for the technique to become practical in the clinical environment.