Ping-Hong Lai

Neuronal Specificity of Acupuncture Response: A fMRI Study with Electroacupuncture

Recently, neuronal correlates of acupuncture stimulation in human brain have been investigated by functional neuroimaging. The preliminary findings suggest that acupuncture at analgesic points involves the pain-related neuromatrix and may have acupoint-brain correlation. Although multiple models of control stimulations have been applied to address the specificity of the needling effect clinically, their impacts have not been evaluated by functional neuroimaging. With the advantage of objective parameter setting, electroacupuncture (EA) was used in this study to devise three distinct controls for real EA, i.e., mock EA (no stimulation), minimal EA (superficial and light stimulation), and sham EA (same stimulation as real EA) applied at nonmeridian points. Fifteen healthy volunteers received real EA at analgesic point Gallbladder 34 (Yanglinquan), sham EA, and one of either mock EA or minimal EA over the left leg in counter-balanced orders. Multisubject analysis showed that sham EA and real EA both activated the reported distributed pain neuromatrix. However, real EA elicited significantly higher activation than sham EA over the hypothalamus and primary somatosensory-motor cortex and deactivation over the rostral segment of anterior cingulate cortex. In the comparison of minimal EA versus mock EA, minimal EA elicited significantly higher activation over the medial occipital cortex. Single-subject analysis showed that superior temporal gyrus (encompassing the auditory cortex) and medial occipital cortex (encompassing the visual cortex) frequently respond to minimal EA, sham EA, or real EA. We concluded that the hypothalamus-limbic system was significantly modulated by EA at acupoints rather than at nonmeridian points, while visual and auditory cortical activation was not a specific effect of treatment-relevant acupoints and required further investigation of the underlying neurophysiological mechanisms.

Multi-detector row computed tomography angiography in diagnosing spinal dural arteriovenous fistula : Initial experience

Background and Purpose— Multi-detector computed tomographic (MDCT) angiography is a recently developed imaging technique that can study small vessels such as medullary arteries and veins. The purpose of this study was to evaluate MDCT angiography in diagnosing SDAVF. Methods— Eight patients with initial magnetic resonance imaging (MRI) and clinical findings suggestive of spinal dural arteriovenous fistula (SDAVF) and 8 control subjects underwent MDCT angiography. Both MDCT angiography and catheter angiography were performed within 5 days in patients with SDAVFs. The results of MDCT angiography in patients with SDAVFs were compared with those of catheter angiography. Results— MDCT angiography detected engorged perimedullary draining veins and correctly localized the fistula of the SDAVFs, and correlated well with catheter angiography. Fistula was at the thoracic level in 7 patients, and sacral level in 1 patient. MDCT angiography did not visualize the engorged perimedullary venous plexus in the control group. Conclusion— MDCT angiography correlated well with catheter angiography in diagnosing SDAVFs. It might play a role in shortening the length of the catheter angiography in diagnosing this disease.

Detection of Subarachnoid Hemorrhage at Acute and Subacute/Chronic Stages: Comparison of Four Magnetic Resonance Imaging Pulse Sequences and Computed Tomography

Background: Acute subarachnoid hemorrhage (SAH) has traditionally been diagnosed by computed tomography (CT); however, fluid‐attenuated inversion recovery (FLAIR) is a magnetic resonance imaging (MRI) modality currently used to detect acute SAH. CT is insensitive in the detection of subacute or chronic SAH. The purpose of this study was to compare 4 MRI pulse sequences and CT in the detection of SAH in acute and subacute‐to‐chronic stages. Methods: From 2001‐2003, we collected data for 22 patients (12 men and 10 women, aged 35‐80 years) with SAH due to ruptured aneurysm (n = 11), trauma (3), or unknown origin (8). All patients underwent MRI and CT examination, with an interval of less than 12 hours between the 2 procedures. We divided patients into 2 groups according to the time from symptom onset to MRI evaluation: patients with MRI performed less than or equal to 5 days post‐ictus had acute‐stage illness, whereas patients with MRI performed from day 6‐30 post‐ictus had a subacute‐to‐chronic condition. MRI (1.5‐T) pulse sequences comprised spin‐echo T1‐weighted, fast spin‐echo T2‐weighted, FLAIR, and gradient‐echo (GE) T2*‐weighted images. Results: In the acute‐stage group, SAH was seen as an area of high signal intensity compared with surrounding cerebrospinal fluid in 36.4% of cases on T1‐weighted images, and in 100% on FLAIR images; low signal intensities were seen in 18.2% of cases on T2‐weighted images, and in 90.9% on GE T2*‐weighted images. High‐attenuated SAH was seen on CT in 90.9% of cases. FLAIR (p = 0.008), GE T2*‐weighted images (p = 0.012) and CT images (p = 0.012) were all statistically significant indicators of acute SAH. In the subacute/chronic‐stage group, SAH was detected on T1‐weighted images (36.4% of cases), FLAIR (33.3%), T2‐weighted images (9.1%), GE T2*‐weighted images (100%), and CT (45.5%). GE T2*‐weighted images were significantly superior (p = 0.001) to other MRI pulse sequences and CT as indicators of subacute‐to‐chronic SAH. Conclusion: FLAIR and GE T2* MRI pulse sequences, and CT scans, are all statistically significant indicators of acute SAH. GE T2*‐weighted images are statistically significant indicators of subacute‐to‐chronic SAH, whereas other MRI pulse sequences, and CT scans, are not.

In vivo proton MR spectroscopy of chorea-ballismus in diabetes mellitus

Abstract The most common cause of chorea-ballismus (CB) is a vascular lesion; it is also associated with nonketotic hyperglycaemia in diabetes mellitus (DM) and may be the first manifestation of this disorder. We describe the CT, MRI and proton MR spectroscopy (1H-MRS) of CB in eight patients. Six had hemichorea-hemiballismus (HC-HB) and two bilateral CB. Single-voxel (SV) 1H-MRS was performed using point-resolved spectroscopy (PRESS). Voxels were positioned in the basal ganglia of the patients and control subjects. PRESS was also used to obtain spectroscopic imaging (1H-MRSI) of the slice of interest in two patients. CT showed a slightly dense striatum in all the patients with CB, and T1-weighted images revealed high signal. The CB correlated well with the neuroimaging findings. SV 1H-MRS showed the mean ( ± SD) N-acetylaspartate (NAA)/ creatine (Cr) ratio to be 1.45 ± 0.19 in HC-HB and 1.82 ± 0.06 on the opposite normal side (P = 0.01). The choline (Cho)/Cr ratio was 1.3 ± 0.12 in HC-HB and 1.11 ± 0.13 on the opposite normal side (P = 0.005). A lactate peak was seen in seven patients. The NAA/Cr ratio was 1.44 ± 0.15 in bilateral CB and 1.74 ± 0.16 in the controls (P = 0.017); the Cho/Cr ratios were 1.36 ± 0.1 and 1.19 ± 0.07 (P = 0.015). The low NAA/Cr suggests neuronal loss or damage and the high Cho/Cr probably indicates gliosis. The presence of lactate may suggest mild ischaemia due to acute vascular events during hyperglycaemia and underlying chronic focal cerebrovascular diseases in DM.

In vivo differentiation of aerobic brain abscesses and necrotic glioblastomas multiforme using proton MR spectroscopic imaging.

BACKGROUND AND PURPOSE: Abscesses caused by aerobic bacteria (aerobic abscesses) can simulate intracranial glioblastomas multiforme (GBMs) in MR imaging appearance and single voxel (SV) proton MR spectroscopy of the central cavity. The purpose of our study was to determine whether MR spectroscopic imaging (SI) can be used to differentiate aerobic abscesses from GBMs. Our hypothesis was that metabolite levels of choline (Cho) are decreased in the ring-enhancing portion of abscesses compared with GBMs. MATERIALS AND METHODS: Fifteen patients with aerobic abscesses were studied on a 1.5T MR scanner using an SV method and an SI method. Proton MR spectra of 15 GBMs with similar conventional MR imaging appearances were used for comparison. The resonance peaks in the cavity, including lactate, cytosolic amino acids, acetate, succinate, and lipids, were analyzed by both SV MR spectroscopy and MRSI. In the contrast-enhancing rim of each lesion, peak areas of N-acetylaspartate (NAA), choline (Cho), lipid and lactate (LL), and creatine (Cr) were measured by MRSI. The peak areas of NAA-n, Cho-n, and Cr-n in the corresponding contralateral normal-appearing (-n) brain were also measured. Maximum Cho/Cr, Cho/NAA, LL/Cr-n, and Cho/Cho-n and minimum Cr/Cr-n and NAA/NAA-n ratios in abscesses and GBMs were compared using the Wilcoxon rank sum test. After receiver operating characteristic curve analysis, diagnostic accuracy was compared. RESULTS: Cytosolic amino acid peaks were found in the cavity in 7 of 15 patients with aerobic abscesses. Means and SDs of maximum Cho/Cr, Cho/NAA, LL/Cr-n, and Cho/Cho-n and minimum Cr/Cr-n and NAA/NAA-n ratios were 3.38 ± 1.09, 3.88 ± 2.13, 2.72 ± 1.45, 1.98 ± 0.53, 0.53 ± 0.16, and 0.44 ± 0.09, respectively, in the GBMs, and 1.77 ± 0.49, 1.48 ± 0.51, 2.11 ± 0.67, 0.81 ± 0.21, 0.48 ± 0.2, and 0.5 ± 0.15, respectively, in the abscesses. Significant differences were found in the maximum Cho/Cr (P = .001), Cho/NAA (P = .006), and Cho/Cho-n ratios (P < .001) between abscesses and GBMs. Diagnostic accuracy was higher by Cho/Cho-n ratio than Cho/Cr and Cho/NAA ratios (93.3% versus 86.7% and 76.7%). CONCLUSION: Metabolite ratios and maximum Cho/Cho-n, Cho/Cr, and Cho/NAA ratios of the contrast-enhancing rim were significantly different and useful in differentiating aerobic abscesses from GBMs by MRSI.

Posterior Reversible Encephalopathy Syndrome: Magnetic Resonance Imaging and Diffusion-Weighted Imaging in 12 Cases

Posterior reversible encephalopathy syndrome (PRES) is a potentially devastating neurologic syndrome, but timely treatment may lead to complete reversal of the disease course. We reviewed 12 cases of PRES and describe the clinical history and imaging findings, including conventional magnetic resonance imaging (MRI), diffusion‐weighted imaging (DWI), and calculated apparent diffusion coefficient (ADC) maps, used to establish the diagnosis of PRES. Three male and nine female patients aged between 11 and 70 years (mean, 37 years) with clinical and imaging findings consistent with PRES were enrolled in the study. All patients had undergone conventional MRI and 10 had undergone additional DWI studies. Ten patients had follow‐up MRI studies. DWI was performed using a 1.5T system with a single‐shot spin‐echo echo‐planar pulse sequence. Initial and follow‐up neuroimaging and clinical history were reviewed. Lesions were almost always present over the posterior circulation, mainly the parieto‐occipital region, affecting primarily the white matter. The anterior circulation region, brainstem, cerebellum, deep cerebral white matter, and thalamus were also involved in five cases. Conventional MRI revealed hyperintensity on T2‐ weighted and fluid‐attenuated inversion recovery images. DWI showed isointensity and increased signal intensity on ADC values in all cases, indicating vasogenic edema. Clinical and MRI follow‐up showed that the symptoms and radiologic abnormalities could be reversed after appropriate treatment of the causes of PRES in most patients (9 of 10). In one patient, the ADC value was lower on follow‐up images, indicating cytotoxic edema with ischemic infarct. DWI was a useful complement to MRI in the diagnosis of PRES.

Cerebral Pilocytic Astrocytoma with Spontaneous Intracranial Hemorrhage in Adults

Pilocytic astrocytomas are found predominantly in the pediatric population; reports of these tumors are extremely rare in adults. We report 2 cases of adult pilocytic astrocytoma with intracranial hemorrhage. A 32-year-old male presented with neck stiffness and severe headache, and a 34-year-old male was referred for headache and double vision. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a well-enhanced and circumscribed cystic hemorrhagic tumor with mural nodule over the cerebral hemisphere region. Perfusion-weighted MRI (PWI) was also performed in both patients. The measured relative cerebral blood volume ratios of the mural nodules in these 2 cases were, respectively, 1.34 and 2.81 when compared with normal white matter. After surgical resection, microscopic examination of the lesions showed pilocytic astrocytomas. Since pilocytic astrocytoma and other cystic tumors with mural nodule (such as hemangioblastoma) have similar findings on conventional CT and MRI, PWI is helpful in the differential diagnosis. The literature on hemorrhagic pilocytic astrocytoma is also reviewed.

Fluoroscopic Guidance of Retrograde Exchange of Ureteral Stents in Women

OBJECTIVE The purpose of this study was to review our experience with fluoroscopically guided retrograde exchange of ureteral stents in women. MATERIALS AND METHODS During a 48-month period, 28 women (age range, 38-76 years) were referred to our department for retrograde exchange of a ureteral stent. The causes of urinary obstruction were tumor compression in 26 patients and benign fibrotic stricture in two patients. A large-diameter snare catheter (25-mm single loop or 18- to 35-mm triple loop) or a foreign body retrieval forceps (opening width, 11.3 mm) was used to grasp the bladder end of the stent under fluoroscopic guidance. The technique entailed replacement of a patent or occluded ureteral stent with a 0.035- or 0.018-inch guidewire with or without the aid of advancement of an angiographic sheath. RESULTS A total of 54 ureteral stents were exchanged with a snare catheter in 42 cases or a forceps in 12 cases. One stent misplaced too far up the ureter was replaced successfully through antegrade percutaneous nephrostomy. Ten occluded stents, including one single-J stent, were managed with a 0.018-inch guidewire in three cases, advancement of an angiographic sheath over the occluded stent into the ureter in five cases, and recannulation of the ureteral orifice with a guidewire in two cases. No complications of massive hemorrhage, ureter perforation, or infection were encountered. CONCLUSION With proper selection of a snare or forceps catheter, retrograde exchange of ureteral stents in women can be easily performed under fluoroscopic guidance with high technical success and a low complication rate.

Spontaneous Regression of Lumbar Herniated Disc

Intervertebral disc herniation of the lumbar spine is a common disease presenting with low back pain and involving nerve root radiculopathy. Some neurological symptoms in the majority of patients frequently improve after a period of conservative treatment. This has been regarded as the result of a decrease of pressure exerted from the herniated disc on neighboring neurostructures and a gradual regression of inflammation. Recently, with advances in magnetic resonance imaging, many reports have demonstrated that the herniated disc has the potential for spontaneous regression. Regression coincided with the improvement of associated symptoms. However, the exact regression mechanism remains unclear. Here, we present 2 cases of lumbar intervertebral disc herniation with spontaneous regression. We review the literature and discuss the possible mechanisms, the precipitating factors of spontaneous disc regression and the proper timing of surgical intervention.

Diffuse Large B-cell Lymphoma of the Cerebellopontine Angle in a Patient with Sudden Hearing Loss and Facial Palsy

Primary lymphoma of the cerebellopontine angle (CPA) is rare in the central nervous system. To our knowledge, there have only been 14 cases reported worldwide so far. Here, we report our findings in a 57-year-old man, who presented with bilateral sudden hearing loss followed by left facial palsy within 1 month. Radiologic study and magnetic resonance imaging showed a homogeneous enhancing mass, 1.6 x 0.5 x 1.1cm in size, in the left CPA cistern region with mild extension to the left internal auditory canal. The tumor was removed through left retromastoid craniectomy, and the histopathologic diagnosis of the tumor was confirmed as diffuse large B-cell type malignant lymphoma. After a series of tumor surveys, there was no evidence of other original lymphoma. The patient was treated with chemotherapy (including intra-Ommaya injection with methotrexate and Ara-C and systemic injection with vincristine, methotrexate and ifosfamide) for the primary CPA lymphoma. He was still alive 19 months after the initial treatment.