Influence of tumor characteristics on correction differences between cone-beam computed tomography-guided patient setup strategies in stereotactic body radiation therapy for lung cancer.

BACKGROUND: To evaluate the correction differences between vertebra and tumor matching as cone-beam computed tomography (CBCT)-guided setup strategies in lung stereotactic body radiation therapy (SBRT), and the correlations with tumor characteristics such as size, mobility, and location. METHODS: The manual registrations for 33 lung tumors treated with SBRT were retrospectively performed by matching thoracic vertebrae for vertebra matching and then by matching CBCT-visualized tumors within the internal target volume obtained from a four-dimensional CT dataset for tumor matching. RESULTS: The mean correction difference between the two matching methods during the SBRT fractions was larger in the anterior-posterior direction (2.7 mm) than in the superior-inferior (2.1 mm) and left-right (1.4 mm) directions, with differences of less than 5 mm in 90% of the total 134 CBCT fractions. The X-axis and direct distances from the central axis to the tumor had significant correlations with the correction differences in all three directions, while the mobility-related parameters were correlated only in the superior-inferior direction. The absolute differences in lung-dose parameters after applying the margins (3.4-6.5 mm) required for the setup errors from vertebra matching relative to tumor matching were mild, with values of 1.95 Gy for the mean lung dose and 3.9% for V20. CONCLUSION: The setup differences between vertebra and tumor matching in the CBCT-guided setup without rotation correction were increased in tumors located long distances from the central axis. The additional safety margins of 3.4-6.5 mm were required for the setup errors from vertebra matching. KEY POINTS: Significant findings of the study The correction difference between the vertebra and tumor matching as CBCT-guided setup strategies was the largest in the anterior-posterior direction and significantly correlated with the X-axis and direct distances from the central axis to the tumor. What this study adds Setup differences between vertebra and tumor matching in the CBCT-guided setup were increased in tumors located long distances from the central axis. The additional safety margins of 3.4-6.5 mm were required for the setup errors from vertebra matching.

Variability in Observer Performance Between Faculty Members and Residents Using Breast Imaging Reporting and Data System (BI-RADS)-Ultrasound, Fifth Edition (2013).

BACKGROUND: Ultrasonography (US) is a useful tool for breast imaging, yet is highly operator-dependent. OBJECTIVES: We evaluated inter-observer variability and performance discrepancies between faculty members and radiology residents when describing breast lesions, by the fifth edition of breast imaging reporting and data system (BI-RADS)-US lexicon, and then attempted to identify whether inter-observer variability could be improved after one education session. PATIENTS AND METHODS: In total, 50 malignant lesions and 70 benign lesions were considered in our retrospective study. Two faculty members, two senior residents, and two junior residents separately assessed the US images. After the first assessment, the readers received one education session, and then reassessed the images in a random order. Inter-observer variability was measured using the kappa coefficient (κ). Performance discrepancy was evaluated by receiver operating characteristic (ROC) curves. RESULTS: For the faculty members, fair-to-good agreement was obtained in all descriptors and final assessment, while for residents, poor-to-moderate agreement was obtained. The areas under the ROC curves were 0.78 for the faculty members, 0.59 for the senior residents, and 0.52 for the junior residents, respectively. Diagnostic performance was significantly higher in the faculty members than the senior and junior residents (P = 0.0001 and < 0.0001, respectively). After one education session, the agreement in the final assessment was one level higher in the faculty members and senior residents, yet in the senior residents, the degree of agreement was still only fair. Moreover, in the junior residents, there was no improvement. CONCLUSION: Investigative assessment of breast US by residents is inadvisable. We recommend continued professional resident training to improve the degree of agreement and performance.

The Influence of Flush Methods on Transfemoral Catheter Cerebral Angiography: Continuous Flush versus Intermittent Flush.

PURPOSE: To evaluate the influence of different flush methods on transfemoral cerebral angiography (TFCA). MATERIALS AND METHODS: This single-blind randomized controlled trial included 50 patients who had undergone TFCA. Balanced block randomization was used to allocate participants into intermittent-flush (n = 25) and continuous-flush (n = 25) groups. Differences in procedure duration, amounts of contrast medium and heparinized saline used, heparin dose, blood loss, fluoroscopy time, radiation dose, and occurrence of new embolic signal (NES) on diffusion-weighted imaging (DWI) were compared between the two groups. RESULTS: The procedure duration was shorter in the continuous-flush group (mean 26.5 min ± 3.7) than in the intermittent-flush group (mean 29.6 min ± 2.8) (P = .004). Amounts of injected contrast medium (mean 20.2 mL ± 4.4 vs 57.1 mL ± 9.0), wasted heparinized saline (mean 19.8 mL ± 9.6 vs 92.3 mL ± 16.7), and aspirated blood (mean 4.7 mL ± 1.3 vs 13.2 mL ± 2.9) were lower in the continuous-flush group than in the intermittent-flush group (P < .001). The amount of injected (or infused) heparinized saline, heparin dose, fluoroscopy time, radiation dose, and occurrence of NES on DWI did not differ between the groups (P > .05). CONCLUSIONS: The use of continuous flushing during TFCA reduced the procedure time, amount of contrast medium needed, amount of wasted heparinized saline, and blood loss, but no difference in the occurrence of NES on DWI was noted between the groups.

Usefulness of target delineation based on the two extreme phases of a four-dimensional computed tomography scan in stereotactic body radiation therapy for lung cancer.

BACKGROUND: An evaluation of the usefulness of target delineation based only on the two extreme phases of a four-dimensional computed tomography (4D CT) scan in lung stereotactic body radiation therapy (SBRT). METHODS: Seventeen patients treated with SBRT via 4D CT scans for lung cancer were retrospectively enrolled. Volumetric and geometric analyses were performed for the internal target volumes (ITVs) and planning target volumes (PTVs) generated using different respiratory phases (all phases and 2 extreme phases) and setup margins (3 mm and 5 mm). RESULTS: As the setup margins were added to the ITVs, the overlap percentage between the PTVs based on all phases and the two extreme phases increased (85.1% for ITVs, 89.8% for PTVs_3 mm, and 91.3% for PTVs_5 mm), and there were no differences according to the tumor parameters, such as the gross tumor volume and 3D mobility. The missing-volume differences for ITVs derived from cone-beam CT images also decreased, with values of 5.3% between ITVs, 0.5% between PTVs_3 mm, and 0.2% between PTVs_5 mm. Compared with the plan based on all phases and a 3 mm margin, the average lung-dose differences found for the PTV based on the two extreme phases and a 5 mm margin were 0.41 Gy for the mean lung dose and 0.93% for V20. CONCLUSIONS: Regardless of tumor characteristics, PTV construction based only on the two extreme phases and a 5 mm setup margin may be a useful tool for reducing the clinical workload involved in target delineation in SBRT for lung cancer.

Reconstitution of internal target volumes by combining four-dimensional computed tomography and a modified slow computed tomography scan in stereotactic body radiotherapy planning for lung cancer.

BACKGROUND: To evaluate the volumetric and geometric differences in the ITVs generated by four-dimensional (4D) computed tomography (CT), a modified slow CT scan, and a combination of these CT methods in lung cancer patients treated with stereotactic body radiotherapy (SBRT). METHODS: Both 4D CT and modified slow CT using a multi-slice CT scanner were performed for SBRT planning in 14 patients with 15 pulmonary targets. Volumetric and geometric analyses were performed for (1) ITVall, generated by combining the gross tumor volumes (GTVs) from all 8 phases of the 4D CT; (2) ITV2, generated by combining the GTVs from 2 extreme phases of the 4D CT; (3) ITVslow, derived from the GTV on the modified slow CT scan; (4) ITVall+slow, generated by combining ITVall and ITVslow; and (5) ITV2+slow, generated by combining ITV2 and ITVslow. Three SBRT plans were performed using 3 ITVs to assess the dosimetric effects on normal lung caused by the various target volumes. RESULTS: ITVall (11.8 ± 8.3 cm3) was significantly smaller than ITVall+slow (12.5 ± 8.9 cm3), with mean values of 5.8% for the percentage volume difference, and a mean of 7.5% of ITVslow was not encompassed in ITVall. The geometric coverages of ITV2 and ITVslow for ITVall were 84.7 ± 6.6% and 76.2 ± 9.3%, respectively, but the coverage for ITVall increased to 90.9 ± 5.9% by using the composite of these two ITVs. There were statistically significant increases in the lung-dose parameters of the plans based on ITVall+slow compared to the plans based on ITVall or ITV2+slow. However, the magnitudes of these differences were relatively small, with a value of less than 3% in all dosimetric parameters. CONCLUSIONS: Due to its ability to provides additional motion information, the combination of 4D CT and a modified slow CT scan in SBRT planning for lung cancer can be used to reduce possible errors in true target delineation caused by breathing pattern variations.

The impact of respiratory gating on lung dosimetry in stereotactic body radiotherapy for lung cancer.

The purpose of this study was to evaluate the impacts of respiratory gating and different gating windows (GWs) on lung dosimetry in stereotactic body radiotherapy (SBRT) for lung cancer. Gated SBRT plans were developed using the four-dimensional computed tomography data from 17 lung cancer patients treated with SBRT. Using amplitude-based end-exhalation gating, we established 2 fixed GWs with approximate duty cycles of 50% (50% GW) and 25% (25% GW), respectively, for this study. For highly mobile tumors (3D mobility > 10 mm), additional benefits in lung-dose reductions were achieved with the 25% GW, as a result of inadequate mobility and planning target volume reductions obtained with the 50% GW. In these tumors, the absolute differences compared to the non-gated and 50% gated plans, were 0.5 Gy and 0.33 Gy for the mean lung dose and 1.11% and 0.71% for the V20, respectively. Dosimetric benefits were achieved with the 50% GW, compared with the non-gated plan, for tumors with both low mobility and small volume (gross tumor volume ≤ 10 cc). Among the identified predictive factors of dosimetric benefits, the lateral distance from midspinal canal and the motion range in anterior-posterior direction might be stronger factors because of their correlations with many of the lung-dose parameters and greater predictive capacity. The results of the present study might facilitate the selection of appropriate patients and the optimal GW according to the tumor characteristics for gated lung SBRT.

Auditory imagery modulates frequency-specific areas in the human auditory cortex.

Neural responses in early sensory areas are influenced by top-down processing. In the visual system, early visual areas have been shown to actively participate in top-down processing based on their topographical properties. Although it has been suggested that the auditory cortex is involved in top-down control, functional evidence of topographic modulation is still lacking. Here, we show that mental auditory imagery for familiar melodies induces significant activation in the frequency-responsive areas of the primary auditory cortex (PAC). This activation is related to the characteristics of the imagery: when subjects were asked to imagine high-frequency melodies, we observed increased activation in the high- versus low-frequency response area; when the subjects were asked to imagine low-frequency melodies, the opposite was observed. Furthermore, we found that A1 is more closely related to the observed frequency-related modulation than R in tonotopic subfields of the PAC. Our findings suggest that top-down processing in the auditory cortex relies on a mechanism similar to that used in the perception of external auditory stimuli, which is comparable to early visual systems.

Transcranial focused ultrasound to the thalamus is associated with reduced extracellular GABA levels in rats.

OBJECTIVE: Transcranial focused ultrasound (FUS), with its ability to non-invasively modulate the excitability of region-specific brain areas, is gaining attention as a potential neurotherapeutic modality. The aim of this study was to examine whether or not FUS administered to the brain could alter the extracellular levels of glutamate and γ-aminobutyric acid (GABA), which are representative excitatory and inhibitory amino acid neurotransmitters, respectively. METHODS: FUS, delivered in the form of a train of pulses, was applied to the thalamus of Sprague-Dawley rats transcranially. Glutamate and GABA were directly sampled from the frontal lobe of the rat brain via a direct microdialysis technique before, during, and after the sonication. The dialysate concentrations were determined by high-performance liquid chromatography. RESULTS: The individual levels of the neurotransmitters sampled were normalized to the baseline level for each rat. In terms of the changes in extracellular glutamate levels, there was no difference between the FUS-treated group and the unsonicated control group. However, extracellular GABA levels started to decrease upon sonication and remained reduced (approximately 20% below baseline; repeated-measures ANOVA, p < 0.05, adjusted for multiple comparisons) compared to the control group. CONCLUSION: The ability to modulate region-specific brain activity, along with the present evidence of the ability to modulate neurotransmission, demonstrates the potential utility of FUS as a completely new non-invasive therapeutic modality.

Comparisons of glenoid bony defects between normal cadaveric specimens and patients with recurrent shoulder dislocation: an anatomic study.

BACKGROUND: The location and degree of bony defects that can affect clinical outcomes remains controversial in recurrent shoulder dislocation. The purpose of this study was to define the most common location of glenoid bony defects in patients with recurrent shoulder dislocation. MATERIALS AND METHODS: We analyzed the shape and aspect ratio of 44 glenoids from deceased donors. Glenoid size was analyzed using a 3-dimensional (3D) computed tomography (CT) scan in 24 patients with recurrent shoulder dislocation who underwent arthroscopic Bankart repair. We measured the distances from the center of the longitudinal axis of the glenoid to the anterior glenoid rim at 9 positions, 10° apart, from 3:00 to 6:00 o'clock positions in the cadaver and patient groups. We compared the quantification of glenoid defects in the 24 patients using the 3D CT scan. A predictive model based on a discriminant analysis was developed. RESULTS: The largest length differences of the glenoid were at the 3:20 o'clock position. When percentage of bone antidefect of the 3:20 o'clock position was used, the model predicted the existence of a defect with 89.7% hit ratio. CONCLUSIONS: The major direction of the glenoid defect was in a more anterior position rather than the anteroinferior glenoid in patients with recurrent shoulder dislocation. The 3:20 o'clock position was most common location of glenoid defect in shoulder instability. This pattern of bone loss should be considered by the surgeon when operating on these patients, especially when performing arthroscopic procedures for Bankart repair or bone block operations to the glenoid.

Acetazolamide-challenged perfusion magnetic resonance imaging for assessment of cerebrovascular reserve capacity in patients with symptomatic middle cerebral artery stenosis: comparison with technetium-99m-hexamethylpropyleneamine oxime single-photon emission computed tomography.

OBJECTIVES: Acetazolamide-challenged perfusion magnetic resonance imaging (MRI) has been shown as a method for assessment of cerebrovascular reserve (CVR) capacity in patients with atherosclerotic steno-occlusive disease of internal carotid artery. We have assessed the feasibility of the acetazolamide-challenged perfusion MRI for evaluating CVR in symptomatic patients with severe middle cerebral artery (MCA) stenosis (≥70%) by comparison with the acetazolamide-challenged technetium-99m-hexamethylpropyleneamine oxime (HMPAO) single-photon emission computed tomography (SPECT). METHODS: Seventeen prospectively enrolled patients with symptomatic unilateral MCA stenosis underwent technetium-99m-hexamethylpropyleneamine oxime SPECT and perfusion MRI without and with acetazolamide challenge, respectively. Acetazolamide-challenged SPECT and perfusion MRI were compared quantitatively by Region of interest (ROI) analysis. RESULTS: At all ROIs, there were no significant differences in percent change between SPECT and perfusion MRI. Patients with impaired CVR showed significant decreases in the percent changes of respective cerebral blood flow (P=.016) and respective cerebral blood volume (P=.029). CONCLUSION: Acetazolamide-challenged perfusion MRI is feasible for evaluating CVR in symptomatic patients with severe MCA stenosis quantitatively.

Measurement of precuneal and hippocampal volumes using magnetic resonance volumetry in Alzheimer's disease.

BACKGROUND AND PURPOSE: Alzheimer's disease (AD) is associated with structural alterations in the medial temporal lobe (MTL) and functional alterations in the posterior cortical region, especially in the early stages. However, it is unclear what mechanisms underlie these regional discrepancies or whether the posterior cortical hypometabolism reflects disconnection from the MTL lesion or is the result of local pathology. The precuneus, an area of the posteromedial cortex that is involved in the early stages of AD, has recently received a great deal of attention in functional neuroimaging studies. To assess the relationship between the precuneus and hippocampus in AD, we investigated the volumes of these two areas using a magnetic resonance volumetric method. METHODS: Twenty-three subjects with AD and 14 healthy age-matched controls underwent T1-weighted three-dimensional volumetric brain magnetic resonance imaging. Volumetric measurements were performed in the precuneus and hippocampus. RESULTS: Compared to controls, AD patients exhibited a significant reduction in total precuneal volume, which was more prominent on the right side, and significant bilateral reductions in hippocampal volume. No correlation was found between the total volumes of the precuneus and hippocampus in the AD group. CONCLUSIONS: These results suggest that volumetric measurements of both the precuneus and hippocampus are useful radiological indices for the diagnosis of AD. Furthermore, the lack of correlation is attributable to local pathology rather than being a secondary consequence of MTL pathology.

Concomitant inflammatory pseudotumor of the temporal bone and lung: a case report.

Inflammatory pseudotumors are histologically benign but locally destructive lesions that are usually found in the lung, although some cases of temporal bone involvement have been reported. To the best of our knowledge, no case of simultaneous involvement of the temporal bone and the lung has been previously reported in the literature. We describe such a case in a 39-year-old man. The temporal bone lesion was removed in its entirety, and the lung lesion was treated with steroid therapy. At the 2-month follow-up, the size of the lung mass on chest x-ray was significantly reduced, and at 1 year, the patient was asymptomatic.

Radiographic and CT findings in complications following pulmonary resection.

A variety of pulmonary resection techniques are currently available, including pneumonectomy (intrapleural, extrapleural, intrapericardial, and sleeve pneumonectomy), lobectomy, and limited resection (sleeve lobectomy, segmentectomy, nonanatomic parenchyma-sparing resection). However, pulmonary resection is often followed by postoperative complications that differ according to the type of surgery and the time elapsed since surgery was performed. The most common complications are bleeding, pulmonary edema, atelectasis, pneumonia, persistent air leak, bronchopleural fistula, and empyema. Other, less frequent complications include cardiac herniation, lung torsion, chylothorax, anastomotic dehiscence, wound infection, esophagopleural fistula, and recurrent tumor. The radiologist plays a major role in the diagnosis of various complications following pulmonary resection. Unfortunately, chest radiography has a relatively low diagnostic accuracy in the detection of these complications. When radiographic findings are subtle or equivocal, computed tomography frequently allows more accurate identification of the disease process. Several complications that follow pulmonary resection are life-threatening and require prompt management. Therefore, knowledge of the diverse radiologic appearances of these complications as well as familiarity with the clinical settings in which specific complications are likely to occur are vital for prompt, effective treatment.