Zhao-Xin Wang

Peripheral pulmonary nodules: Relationship between multi-slice spiral CT perfusion imaging and tumor angiogenesis and VEGF expression

BackgroundThe aim of this study is to investigate the relationship between16-slice spiral CT perfusion imaging and tumor angiogenesis and VEGF (vascular endothelial growth factor) expression in patients with benign and malignant pulmonary nodules, and differential diagnosis between benign and malignant pulmonary nodules.MethodsSixty-four patients with benign and malignant pulmonary nodules underwent 16-slice spiral CT perfusion imaging. The CT perfusion imaging was analyzed for TDC (time density curve), perfusion parametric maps, and the respective perfusion parameters. Immunohistochemical findings of MVD (microvessel density) measurement and VEGF expression was evaluated.ResultsThe shape of the TDC of peripheral lung cancer was similar to those of inflammatory nodule. PH (peak height), PHpm/PHa (peak height ratio of pulmonary nodule to aorta), BF (blood flow), BV (blood volume) value of peripheral lung cancer and inflammatory nodule were not statistically significant (all P > 0.05). Both showed significantly higher PH, PHpm/PHa, BF, BV value than those of benign nodule (all P < 0.05). Peripheral lung cancer showed significantly higher PS (permeability surface) value than that of inflammatory nodule and benign nodule (all P < 0.05). BV, BF, PS, MTT, PH, PHpm/PHa, and MVD among three groups of peripheral lung cancers were not significantly (all P > 0.05). In the case of adenocarcinoma, BV, BF, PS, PHpm/PHa, and MVD between poorly and well differentiation and between poorly and moderately differentiation were statistically significant (all P < 0.05). The peripheral lung cancers with VEGF positive expression showed significantly higher PH, PHpm/PHa, BF, BV, PS, and MVD value than those of the peripheral lung cancer with VEGF negative expression, and than those of benign nodule with VEGF positive expression (all P < 0.05). When investigating VEGF negative expression, it is found that PH, PHpm/PHa, and MVD of inflammatory nodule were significantly higher than those of peripheral lung cancer, PS of inflammatory nodule were significantly lower than that of peripheral lung cancer (all P < 0.05). PH, PHpm/PHa, BF, and BV of benign nodule were significantly lower than those of inflammatory nodule (all P < 0.05), rather than PS and MTT (mean transit time) (all P > 0.05). PH, PHpm/PHa, BV, and PS of benign nodule were significantly lower than those of peripheral lung cancer (all P < 0.05). In the case of VEGF positive expression, MVD was positively correlated with PH, PHpm/PHa, BF, BV, and PS of peripheral lung cancer and PS of benign nodule (all P < 0.05).ConclusionMulti-slice spiral CT perfusion imaging closely correlated with tumor angiogenesis and reflected MVD measurement and VEGF expression. It provided not only a non-invasive method of quantitative assessment for blood flow patterns of peripheral pulmonary nodules but also an applicable diagnostic method for peripheral pulmonary nodules.

Broca's area plays a role in syntactic processing during Chinese reading comprehension

Event-related functional magnetic resonance imaging (ER-fMRI) was adopted to examine brain activation of syntactic processing in reading logographic Chinese. While fMRI data were obtained, 15 readers of Chinese read individually presented sentences and performed semantic congruency judgments on three kinds of sentences: Congruous sentences (CON), sentences with a semantic violation (SEM), and sentences with both semantic and syntactic violations (SEM+SYN). The two types of incongruous sentences were matched in the degree of semantic plausibility. Three brain regions were identified showing significantly different levels of percent signal change across the three conditions, including BA44 in the left inferior frontal gyrus (IFG) and both BA9 and BA10/46 in the left middle frontal gyrus (MFG). Furthermore, the mean percent signal change in the left BA44 observed in the SEM+SYN condition was significantly stronger than that in either the SEM or the CON condition, while the latter two conditions were at a similar level, implying an important role of this area in Chinese syntactic processing. These results, in conjunction with those found in alphabetic scripts, suggest that there are some common neural substrates underlie syntactic processing across distinctive writing systems such as the logographic Chinese and the alphabetic English.

Cross‐modal temporal order memory for auditory digits and visual locations: An fMRI study

A function of working memory is to remember the temporal sequence of events, often occurring across different sensory modalities. To study the neural correlates of this function, we conducted an event‐related functional magnetic resonance imaging (fMRI) experiment with a cross‐modal memory task. Subjects were required to recall auditory digits and visual locations either in mixed order (cross‐modality) or in separate order (within‐modality). To identify the brain regions involved in the memory of cross‐modal temporal order, we compared the blood oxygenation level‐dependent (BOLD) response between the mixed and the separate order tasks. As a control, cortical areas sensitive to the memory load were mapped by comparing the 10‐item condition with the 6‐item condition in the separate order task. Results show that the bilateral prefrontal, right premotor, temporo‐parietal junction (TPJ) and left superior parietal cortices had significantly more activation in the mixed task than in the separate task. Some of these areas were also sensitive to the memory load, whereas the right prefrontal cortex and TPJ were relatively more sensitive to the cross‐modal order but not the memory load. Our study provides potential neural correlates for the episodic buffer, a key component of working memory as proposed previously [Baddeley. Trends Cogn Sci 2000;4:417–423]. Hum. Brain Mapping 22:280–289, 2004.

Functional comparison of primacy, middle and recency retrieval in human auditory short-term memory: an event-related fMRI study

Primacy and recency effects refer to the better performance or shorter response time on the first and last items than the middle ones of a memory list. In order to investigate its neural basis in auditory short-term memory, event-related fMRI was used to measure brain activities when subject was recalling the first, the last, or the middle items. Recalling the middle item was associated with more extensive activation in the left parietal and visual cortex, basal ganglia, and dorsal cerebellum. Recalling items from different serial positions also resulted in different activation time courses in the bilateral primary auditory cortex, left prefrontal cortex and left premotor cortex. These data indicate that the auditory cortex may serve as a transient storage or the auditory input buffer, which seems to play an important role in the primacy and recency effects.

Functional magnetic resource imaging assessment of altered brain function in hypothyroidism during working memory processing

CONTEXT Hypothyroidism is related to multiple cognitive deficits including working memory dysfunction, of which the underlying neural correlates were rarely studied. In this study, the impact of hypothyroidism on neural circuits involved in working memory processing was explored by functional magnetic resource imaging (fMRI). DESIGN Using fMRI, we conducted a longitudinal study investigating alterations of brain function during a working memory task, the four-digit backward recall (BR) and forward recall (FR), in hypothyroid patients and controls. METHODS fMRI scan was used in 13 female patients at two time points: before and after having been treated with levothyroxine (L-T(4)) for ∼6 months, and 12 matched euthyroid controls were also scanned. Wechsler Memory Scale-Chinese Revision was used to assess the memory states of each participant. RESULTS The hypothyroid patients showed poorer memory states than that in controls. Furthermore, significant differences of task-induced deactivation (TID, task-dependent decreases in neural activity relative to rest) between patients and controls were found in the bilateral medial prefrontal cortices, posterior cingulate cortices, and left inferior partial lobule (P<0.05). These regions were considered as parts of a task-negative network, namely the default mode network (DMN). Concretely, relative to controls, patients showed diminished TID during BR in contrast to FR. After the L-T(4) treatment, neither the poor memory states nor the alteration of TID was detectable in patients. CONCLUSION Hypothyroidism is related to alterations of TID within DMN regions during working memory processing. These exploratory findings may imply potential neural correlates in hypothyroidism-related cognitive deficits and their recoveries.

Verbal working memory deficits in abstinent heroin abusers

Background: A prevailing belief is that opioids tend not to impair cognitive performance in opioid-dependent users. However, the impact of heroin abuse on verbal memory, especially on working memory, is not well studied and the results available are inconsistent. Objective: This study was carried out to test the hypothesis that abstinent heroin abusers have intact working memory capacity. Methods: N-back task and backward digit span task were used to measure the verbal working memory capacity in 28 abstinent heroin abusers and 25 controls matched for age, education level and gender. Forward digit span task was used as a control task to measure short-term memory capacity. Results: Compared with the control subjects, heroin abusers showed normal backward/forward digit spans but significant performance impairment in the n-back task. Conclusion: Abstinent heroin abusers have intact short-term memory capacity but impaired verbal working memory capacity.