The current status of reversal therapy in Japan for elderly patients with head injury treated with antithrombotic agents: A prospective multicenter observational study

Background

Acute exacerbation of head injury in elderly patients due to use of antithrombotic agents has become a concern in countries with aging populations. Reversal agents are recommended for treatment, but its usage is unclear. Therefore, we conducted a prospective observational study in this patient population to monitor usage of reversal therapy.

Methods

The subjects were 721 elderly patients aged ≥65 years old who were hospitalized in 15 centers from December 2019 to May 2021. Patients were divided into groups who did not receive antithrombotic agents (Group A), who received antithrombotic agents, but did not receive reversal therapy (Group B), and were treated with antithrombotic agents and reversal therapy (Group C). Age, gender, mechanism of injury, neurologic and imaging findings on admission, clinical course after admission and surgery, outcomes and complications were compared among these groups. Time from injury to reversal therapy was examined based on outcomes to investigate trends in the timing of administration of the reversal agent.

Results

Acute exacerbation during the clinical course occurred in 9.8 %, 15.8 % and 31.0 % of cases in Groups A, B and C, respectively, and differed significantly among the groups. On head CT, the incidences of hematoma were 35.7 %, 36.5 % and 60.4 %, respectively, with this incidence being significantly higher in Group C; and the respective rates of craniotomy were 18.8 %, 14.0 % and 50.9 %, again with this rate being significantly higher in Group C. The good outcome and mortality rates were 57.1 %, 52.5 % and 35.8 %, and 14.5 %, 18.0 % and 24.5 %, respectively, and both were poorest in Group C. Times from injury to treatment with a reversal agent were significantly shorter in patients without compared to those with acute exacerbation (405.9 vs. 880.8 min) and in patients with favorable outcomes compared to those with unfavorable outcomes (261.9 vs. 543.4 min).

Conclusion

Similarly to previous studies, the incidence of acute exacerbation was increased by use of antithrombotic agents. These results suggest that patients in Japan who require hematoma evacuation due to symptom exacerbation tend to be treated with reversal agents. Although it is difficult to assess the efficacy of reversal therapy from this study, earlier treatment with reversal agents before the occurrence of acute exacerbation may be useful to improve outcomes.

Retrospective Observational Study of Patients With Subdural Hematoma Treated With Idarucizumab

Use of anticoagulants is increasing with the aging of societies. The safe first-line drug is likely to be a direct oral anticoagulant (DOAC), but outcomes of treatment of traumatic brain injury (TBI) with anticoagulants are uncertain. Therefore, we examined the clinical effect of idarucizumab as reversal therapy in elderly patients with TBI who were treated with dabigatran. A retrospective multi-center observational study was performed in patients ≥65 years of age who developed acute traumatic subdural hematoma during treatment with dabigatran and underwent reversal therapy with idarucizumab. The items examined included patient background, neurological and imaging findings at arrival, course after admission, complications, and outcomes. A total of 23 patients were enrolled in the study. The patients had a mean age of 78.9 years. Cause of TBI was fall in 60.9% of the subjects. Mean Glasgow Coma Scale score at arrival was 8.7; anisocoria was present in 31.8% of cases. Exacerbation of consciousness was found in 30.4%, but only in 13.3% of subjects treated with idarucizumab before consciousness and imaging findings worsened. Dabigatran was discontinued in 81.8% of cases after hematoma development, with a mean withdrawal period of 12.1 days. The favorable outcome rate was 21.7%, and mortality was 39.1%. In multi-variate analysis, timing of idarucizumab administration was associated with a favorable outcome. There were ischemic complications in 3 cases (13.1%), and all three events occurred ≥7 days after administration of idarucizumab. These findings suggest that in cases that develop hematoma during treatment with dabigatran, it is important to administer idarucizumab early and restart dabigatran after conditions stabilize.

Analysis of relationship between loading condition and cranial cracking pattern using a three-dimensional finite element model

BACKGROUND

A hairline crack on the cranium can occur even under a small external load or impact and are thus often observed in patients who have experienced an accidental fall or collision. Typical finite element analysis is useful to analyze the stress concentration or the propagation of stress waves. However, a stress propagation model does not accurately reproduce the features of hairline cracks on the cranium. The objective in this study was to reproduce cranial hairline cracks.

METHODS

A three-dimensional finite element model of the cranial bone was developed from a patient CT images. The model consists of the frontal, parietal, occipital and temporal bones, and the bones are connected with the sutures. Additionally, the model comprised three layers; the external and internal tables and the diploe. The model was analyzed using the extended finite element method (X-FEM), and a forming limit diagram (FLD) was embedded in the model. In this study, the model was symmetrized bilaterally using the model developed from the left side of the skull. The FLD in this study was assumed to be a relationship between the maximum and minimum strains when a fracture occurs. A total of 13 typical loadings were applied to the model: loading points on the top, left, and back of the cranium were considered, and at each loading point, loads were applied with four or five different directions, namely perpendicular to the cranium and inclined in the anterior, posterior, superior, or inferior at an angle of 45^∘.

RESULTS

Under all loading conditions, many small cracks formed radially at the loading points. Moreover, some large cracks formed under the certain loading conditions. The crack shapes on the top and left side could be associated with the specific loading directions, whereas cracks on the back did not show distinguishing characteristics depending on the loading directions. The present model was reproduced anatomically and morphologically, and the results were similar to those obtained in previous cadaver experiments.

CONCLUSIONS

Through X-FEM analysis of the FE model embedded with an FLD, hairline cracks in the cranium were reproduced, and a few crack shapes were identified as potential markers for estimating the loading conditions.

A case of tandem stenoses at the proximal common and internal carotid arteries treated with transbrachial stenting: a case report

The transfemoral approach is a common technique for carotid artery stenting. However, it has the risk of distal embolism when stenting for a stenosis of the proximal common carotid artery because of poor stability of the guiding catheter resulting in difficulty in setting the embolic protection device prior to stenting. We present a novel therapeutic approach and technique for the treatment of tandem carotid stenoses including the proximal common carotid artery. A 63-year-old man presented with double stenoses at the common carotid artery and internal carotid artery. We used a transbrachial sheath guide that had a 6 Fr (2.24 mm, 0.088 inch) internal diameter and was 90 cm long, and was specifically designed for direct cannulation to the common carotid artery, like a modified Simmons catheter. Because the sheath guide positioned in the aortic arch made it possible to introduce safely the embolic protection device distal to the internal carotid artery stenosis without touching the plaque at the stenosis with no use of any coaxial catheters or guidewires, carotid artery stenting for tandem stenoses could be successfully carried out. The postoperative course was uneventful. In carotid artery stenting, especially for stenosis of the proximal common carotid artery, the sheath guide designed for transbrachial carotid cannulation was useful in stenting the tandem carotid stenoses.

Risk Factors of Contralateral Microembolic Infarctions Related to Carotid Artery Stenting

This study sought to analyze the incidence of contralateral microembolic infarctions (MIs) on diffusion-weighted imaging (DWI) following protected carotid artery stenting (CAS) and compared the difference of risk factors between ipsilateral and contralateral lesions. From April 2010 to March 2017, 147 CASs in 140 patients were performed. All the patients underwent DWI within 1 week before and 24 hrs after the procedures. CAS was successfully completed in 145 (98.6%) of the 147 procedures. Forty-nine (33.8%) patients with new MIs revealed on postprocedural DWI were enrolled. They were divided into ipsilateral and contralateral groups based on the side of the CAS and MIs. The ipsilateral group indicates patients with MIs exclusively on the side of CAS. The contralateral group includes patients with MIs on the opposite side of the CAS or both sides. Patients with MIs at vertebrobasilar territory were excluded. Patient characteristics, morphology of the carotid artery and aortic arch, and procedural data were retrospectively assessed and compared between the two groups. Twenty-two (15.2%) and 14 (9.7%) patients were assigned to the ipsilateral and contralateral groups, respectively. Advanced age, left-sided stenosis, severe aortic arch calcification (AAC) on chest X-ray and contralateral carotid occlusion significantly increased the occurrence of contralateral MIs. On multivariable logistic regression analysis, severe AAC was statistically more frequent in the contralateral group. In the present study, the incidences of contralateral MIs after CAS is relatively not low. Advanced aortic atherosclerosis is statistically predictive for contralateral MIs. AAC on chest X-ray is a useful finding for estimating aortic atherosclerosis in candidates for CAS.

Surgical removal of an arteriovenous malformation in the anterior perforated substance in a pregnant woman

Background:

A tailor-made treatment is often required in arteriovenous malformations (AVMs) depending on the individual situation. In most cases, treatment strategy is usually determined according to the patient's Spetzler–Martin grade. However, in the present case, we were not able to treat the patient following the usual guidelines because of neurological symptoms and pregnancy.

Case Description:

We describe a rare case of a 31-year-old woman in the 15^th week of gestation who presented with an AVM in the anterior perforated substance (APS). She suffered a sudden coma and hemiplegia. A computed tomographic scan showed an enhanced mass and a huge hematoma in the basal ganglia and temporal lobe. The hematoma was successfully evacuated in an endoscopic procedure. Angiography showed that a 25-mm nidus in the APS was fed by the anterior choroidal arteries (AChAs) and the lenticulostriate arteries (LSAs). Therefore, we attempted to remove the nidus because the patient became alert with mild aphasia and hemiparesis 10 days after hemorrhage. The feeding arteries were cut under motor evoked potential (MEP) monitoring, and the nidus was totally resected leaving two of four AChAs and a single artery with several LSAs. The postoperative course was uneventful, and she gave birth to a healthy baby by caesarian delivery 122 days after the hemorrhage with only minor sequelae.

Conclusions:

Surgical strategy with a device-administered anesthesia are suitable for removing large AVMs even in pregnant women and for the successful outcome of their pregnancies. Even after recovering from a coma and hemiplegia, MEP monitoring is effective for removing large AVMs even when located in the APS.

[A Case of Multiple Atherosclerotic Fusiform Cerebral Aneurysms with Repeated Subarachnoid Hemorrhage]

Pure fusiform aneurysms without dissection are considered to have a low risk of rupture. Furthermore, aneurysm wall with atherosclerotic change tends to be less susceptible to rupture. We present a rare case of multiple atherosclerotic fusiform aneurysms associated with repeated subarachnoid hemorrhage(SAH)during a 9-year observation period. A 34-year-old woman was admitted to our hospital because of SAH. SAH with a temporal hematoma due to a fusiform aneurysm of the right middle cerebral artery(MCA)was detected using computed tomography(CT). Associated fusiform aneurysms were observed in the left posterior cerebral artery(PCA)and the left MCA. The right MCA aneurysm was occluded with angioplastic clipping. Eight years after the first onset, angioplastic clipping was performed on the other two fusiform aneurysms because of their growth. Intraoperative findings showed atherosclerotic change in the parent artery wall, similar to the right MCA aneurysms. The right MCA aneurysm ruptured again 1 year later. The aneurysm was treated with proximal occlusion combined with a bypass from the occipital artery to the distal MCA. The patient was in a stable state, although, she was disabled because of SAH damage. The effects of atherosclerotic fusiform aneurysms, which are rarely encountered, are not well known. Some studies have reported the risk of hemorrhage from these aneurysms. This case suggests the necessity of long-term follow-up for the prediction of aneurysm growth and bleeding. Moreover, proximal occlusion combined with an external bypass is better for the treatment of this type of aneurysm because angioplastic clipping is not curative.

Clinical significance of thickened sphenoid sinus mucosa in Rathke's cleft cyst

Background:

To determine the clinical significance of thickening of the sphenoid sinus mucosa (TSSM) in Rathke's cleft cyst (RCC).

Methods:

We retrospectively reviewed patients with pituitary lesions. A total of 99 patients, who underwent surgery of pituitary lesions between 2008 and 2015, were analyzed to evaluate the clinical significance of TSSM using magnetic resonance imaging. The patients with TSSM were evaluated for their characteristics.

Results:

Of the 99 operations, 15 patients with paranasal sinusitis, direct invasion to the sellar floor, and/or a history of transsphenoidal surgery were excluded. There were 51 pituitary adenomas (PAs), 18 RCCs, and 15 other tumors. TSSM was observed in 6 patients (7.1%). Pathologies included 3 RCCs (16.7%), 1 PA (2.0%), and 2 other lesions. Three RCCs were especially analyzed. The pituitary dysfunction was found in all 3 patients with TSSM, whereas that was noted in 2 of 15 patients (13.3%) without TSSM. The sensitivity was 60%, specificity was 86.7%, and the positive predictive value was 100%. There was no significant difference in the age, thickness of TSSM, symptoms, and squamous metaplasia between patients with and without TSSM.

Conclusions:

TSSM occurs more frequently in RCCs than in PAs. TSSM can potentially suggest hypopituitarism in RCCs. The surgical and/or endocrinological interventions are required for preventing further endocrine deterioration.

Outflow occlusion with A3-A3 anastomosis for a doughnut-shaped partially thrombosed giant A2 aneurysm

Background:

A doughnut-shaped aneurysm, which is defined as a round-shaped aneurysm composed of an intraluminar thrombus and marginal parent artery, is an extremely uncommon subtype of partially thrombosed giant aneurysms. Surgical treatment of this characteristic aneurysm is technically challenging.

Case Description:

We report a rare case of a 79-year-old man with a symptomatic doughnut-shaped giant aneurysm at the A2 portion, which was successfully treated by outflow occlusion with an A3–A3 side-to-side anastomosis. Postoperative angiograms demonstrated no filling of the doughnut-shaped aneurysm and perfusion in the distal right anterior cerebral artery territory via the anastomosis. Follow-up magnetic resonance imaging 1 year after the surgery demonstrated significant diminution of the aneurysm.

Conclusions:

Outflow occlusion with distal revascularization could be an effective surgical option for such a unique aneurysm. To the best of our knowledge, this is the first report of outflow occlusion as a therapy for doughnut-shaped aneurysms.

Steroid-resistant Tolosa-Hunt syndrome with a de novo intracavernous aneurysm: A case report

Background:

We report a case of steroid-resistant Tolosa–Hunt syndrome (THS) with recurrent bilateral painful ophthalmoplegia, accompanied with sphenoid sinusitis, pituitary abscess, and an aneurysm arising from the cavernous portion of the internal carotid artery.

Case Description:

A 53-year-old woman suffered severe left painful ophthalmoplegia. A magnetic resonance image (MRI) revealed thickness of the left cavernous sinus (CS). Steroid was administrated under the diagnosis of THS, and the symptom transiently diminished. However, painful ophthalmoplegia fluctuated bilaterally after tapering the steroid. An MRI showed development of bilateral cavernous lesions associated with sphenoid sinusitis, pituitary abscess, and an aneurysm in the left C4 segment. Biopsy and drainage of the lesions were performed with an endoscopic transsphenoidal procedure. The histological examination showed nonspecific granulomatous inflammation. The methotrexate (MTX) was effective to reduce the CS and pituitary lesions; however, the aneurysm slightly increased and remained unchanged in size thereafter.

Conclusions:

To our knowledge, this is the first report of a growing de novo C4 aneurysm in THS. Surgical intervention and administration of MTX should be attempted in steroid-resistant THS. Careful observation with serial MRI and MR angiography is important to manage the complicated THS.

[Coil Embolization of a Ruptured Anterior Communicating Artery Aneurysm Forming a Pseudoaneurysm: Report of Three Cases]

The formation of an intracranial pseudoaneurysm due to a ruptured saccular aneurysm is a rare condition that exhibits characteristic angiographic findings referred to as "ghost aneurysm" or "snowman's head". Currently, no detailed information about the treatment of this condition is available. Clipping has been reported to be more effective and better for removing massive hematomas than endovascular intervention. Moreover, endovascular coil embolization during the acute phase carries a high risk of repeated aneurysm rupture due to the fragility of the pseudoaneurysmal blood clot. Here, we describe three cases of pseudoaneurysm formation following the rupture of an anterior communicating artery aneurysm, and suggest the possibility that ruptured saccular aneurysms with pseudoaneurysm formation can be treated safely and effectively with endovascular coil embolization.

Ruptured dermoid cyst of the lateral cavernous sinus wall with temporary symptoms: a case report

BACKGROUND

Dermoid cysts are non-neoplastic tumors that arise from defects in the separation of the neuroectoderm. Cyst rupture rarely occurs spontaneously and the most common symptom is headache, followed by seizure. Although many cases of ruptured dermoid cysts present with symptoms, reports of cases that are asymptomatic, or where symptoms disappear, are rare.

CASE PRESENTATION

We report the case of a 66-year-old Asian man with a history of sudden onset headache who was found to have high amounts of fat material in the subarachnoid space and a fat suppression mass in the left cavernous sinus. He underwent oral steroid therapy. Five days after starting medication his headache symptoms disappeared. Routine neurological imaging was then performed without surgical procedure. Magnetic resonance imaging revealed evidence of the remains of a static lesion 6 months after his first visit. He has remained headache free for 10 months since the initial event.

CONCLUSIONS

Although cases of ruptured dermoid cysts presenting with consistent symptoms have been commonly reported, until now there were few reports on asymptomatic cases or cases where symptoms disappeared. We believe that surgical intervention is unnecessary for ruptured dermoid cysts with minimal symptoms.

The "temporary caging" technique for catheter navigation in patients with intracranial wide-necked aneurysms

Endovascular treatment of wide-necked aneurysms with preservation of the parent artery remains a challenge. The authors describe a novel and simple technique to navigate a balloon or stent-delivery catheter across a wide-necked aneurysm in which previously existing methods could have failed to pass the catheter across the neck of the aneurysm, which we have named "temporary caging" technique. The technical results using this method are presented in 6 cases.

Percutaneous transluminal angioplasty in a patient with internal carotid artery stenosis following gamma knife radiosurgery for recurrent pituitary adenoma

BACKGROUND

Intracranial vascular complications following radiosurgery are extremely rare.

CASE DESCRIPTION

We report a case of stenosis in the internal carotid artery 5 years after gamma knife radiosurgery for a recurrent pituitary adenoma. Percutaneous transluminal angioplasty was performed successfully with anatomical and functional improvement.

CONCLUSION

These results suggested the importance of monitoring for arterial stenosis in the long-term follow-up. Moreover, this is the first case of endovascular treatment as an effective therapy for intracranial arterial stenosis due to radiotherapy.

Intraoperative head rotation for clipping anterior communicating artery aneurysms

Background:

The anterior interhemispheric approach provides wide exposure of the anatomy around the anterior communicating artery aneurysm. A disadvantage of this approach is that splitting the interhemispheric fissure is a complicated surgical maneuver. One solution is to hold the fissure horizontally in the operation field. Surgical procedures for bicoronal scalp incision and craniotomy are difficult in the horizontal head position. We developed a modified low anterior interhemispheric approach to minimize damage to the frontal lobe and olfactory nerve by rotating the head after opening the dura.

Methods:

The head is fixed in a prerotated Sugita head holder in a neutral head position. Bicoronal scalp incision and frontal craniotomy are performed and the head holder is rotated 30 degrees clockwise to allow gravity to retract the right frontal lobe. The surgeon can then move to the right side of the patient to obtain a horizontal operation field parallel to the interhemispheric fissure.

Results:

This method was used for 12 patients in the past 6 years. All aneurysms were successfully clipped without any complications related to the procedure. Damage to the frontal lobe was avoided and the olfactory nerve was preserved in all the patients.

Conclusion:

Intraoperative head rotation minimizes surgical damage to the neural structures in the anterior interhemispheric approach.

[Characteristics of cerebral aneurysm clips based on measurements of the opening pressures: basic research using a high-pressure perfusion circuit and a porcine vessel]

BACKGROUND

The closing force of cerebral aneurysm clips is measured according to International Organization for Standardization guidelines. However, it is difficult to predict the risk of a clip using only the closing force. To investigate the clips' detailed characteristics and assess their limits, we used a high-pressure perfusion circuit and measured the critical pressure to the slipping point.

METHODS

Opening pressures were measured for 3 types of Sugita clips using a high-pressure perfusion circuit and a porcine vessel. The opening pressures at different points on various blade lengths and shapes were also measured.

RESULTS

The opening pressure of a short blade clip was higher than that of a long one. In a straight blade of the same length, the opening pressure of the proximal segment of a blade was higher than that at the distal segment.

CONCLUSIONS

Our study showed the characteristics of various clips, such as blade length. These findings suggested that clips should be chosen on a case-by-case basis.

Acute phase endovascular intervention on a pseudoaneurysm formed due to rupture of an anterior communicating artery aneurysm

A 79-year-old woman presented with a subarachnoid hemorrhage. Angiography revealed pseudoaneurysm formation due to rupture of a true saccular anterior communicating artery aneurysm. Coil embolization, limited to the true aneurysm, was performed successfully with a favorable clinical outcome. This procedure can be considered as an alternative treatment option for similar aneurysms in cases where surgical clipping is contraindicated.

Acute phase endovascular intervention on a pseudoaneurysm formed due to rupture of an anterior communicating artery aneurysm

A 79-year-old woman presented with a subarachnoid hemorrhage. Angiography revealed pseudoaneurysm formation due to rupture of a true saccular anterior communicating artery aneurysm. Coil embolization, limited to the true aneurysm, was performed successfully with a favorable clinical outcome. This procedure can be considered as an alternative treatment option for similar aneurysms in cases where surgical clipping is contraindicated.

Assessment of brain compliance using ICP waveform analysis in water intoxication rat model

Intracranial pressure (ICP) monitoring has been used widely for patients with intracranial hypertension. However, the data of mean ICP do not reflect various brain conditions correctly. Therefore, we performed ICP -waveform analysis to assess brain compliance. Data for ICP -waveform analysis were obtained by stereotactic intraventricle puncture. ICP waveform is expressed as a three-phase wave. Analyzed differential waveforms in a water intoxication model and continuous infusion models were evaluated respectively. In the water intoxication models, the second wave (P2) known to reflect compliance is elevated. ICP waveform analysis will be valuable for the assessment of the pathological condition of the brain.

Analysis of intracranial pressure pulse waveform and brain capillary morphology in type 2 diabetes mellitus rats

Diabetes mellitus in neurosurgical patients is known to be a disease with high risks and severe outcomes. However, the mechanism by which diabetes mellitus induces dysfunction of brain tissue is not well known. The hypothesis of this study was that the damage to brain microvasculature in diabetes mellitus results in impaired compliance of the brain. Pathological changes associated with type II diabetes were investigated using a rat model. Pathophysiological changes in diabetic brain tissue were also investigated to confirm cerebral compliance by analyzing intracranial pressure waveforms. Pathologic findings revealed thickening of the basement membrane and fibrous collagen infiltration into the inner basement membrane of the brain microvasculature in diabetes mellitus. Analysis of intracranial pressure waveforms revealed that the P2 portion increased in diabetic rats compared to the control and was increased further with the increase in intracranial pressure. Analysis of the differential pressure curve, with respect to time, demonstrated that intracranial elasticity showed a concomitant increase. Pathologic findings and intracranial pressure waveforms were consistent with changes in brain microvasculature in diabetes mellitus. The increase of elasticity of brain tissue in diabetes mellitus may exacerbate the damage of intracranial disease.

[A case of ruptured internal carotid artery "kissing aneurysms": case report and review of the literature]

OBJECTIVE

A rare case of ruptured kissing aneurysms on the right internal carotid-posterior communicating artery (ICPCA) and -anterior choroidal artery (ICAchA) is reported.

CASE

A 47-year-old female was transferred to our hospital because of subarachnoid hemorrhage (SAH). Cerebral angiography revealed two aneurysms on the right ICPCA and ICAchA. Right frontotemporal craniotomy was performed to obliterate them on the day of admission. Despite the presence of angiographical cleavage, these two aneurysms were attached to each other tightly, and it was extremely difficult to dissect the space between them and premature rupture occurred. A Sugita long straight clip was inserted parallel to internal carotid artery to obliterate the body of ICAchA aneurysm and the neck of ICPCA aneurysm. Another straight clip was applied to the neck of the former aneurysm. Both PCA and AchA could be secured successfully. Postoperatively, although she developed symptomatic vasospasm on the 10th day, she discharged without any neurological deficits 40 days later.

CONCLUSIONS

Because of the difficulty in dissection of aneurysms, the operation for kissing aneurysms has been recognized as hazardous and challenging since Jefferson. We emphasize that a clipping technique described above should be kept in mind as a safe value, though meticulous dissection of each aneurysmal neck followed by independent neck clipping is reasonable.

Impaired pain sensation in mice lacking Aquaporin-1 water channels

Aquaporin-1 (AQP1), a membrane water channel, is expressed in choroid plexus where it contributes to cerebrospinal fluid production. Here, we show that AQP1 is also expressed in the dorsal horn of the spinal cord and the trigeminal nucleus caudalis, regions that process pain information. Within the dorsal root and trigeminal sensory ganglia, AQP1 is concentrated in small diameter cell bodies, most of which give rise to unmyelinated C-fibers. To study the role of AQP1 in pain signaling, we compared acute pain responses in wild-type mice and in mice lacking AQP1. AQP1(-/-) mice had reduced responsiveness to thermal and capsaicin chemical stimuli, but not to mechanical stimuli or formalin. These results provide evidence for AQP1 expression in nociceptive neurons and suggest that AQP1 may play a role in pain signal transduction.

Expression of the Aquaporin-1 Water Channel in Human Glial Tumors

OBJECTIVE

Malignant glial tumors are associated with cerebral edema. The aquaporins (AQPs) are a family of membrane proteins that provide a major pathway for water transport in mammals. In the central nervous system, AQP1 is selectively expressed in the choroid plexus and thought to participate in cerebrospinal fluid production. Prior studies have suggested that AQP1 may be up-regulated in glial tumors, potentially contributing to tumor-associated edema. The objective of this study was to investigate the expression of AQP1 in a large series of human glial tumors.

METHODS

Thirty-six human glial tumors were obtained from the University of California, San Francisco Neurosurgery Tissue Bank. AQP1 expression was evaluated by reverse transcriptase polymerase chain reaction, complementary deoxyribonucleic acid gene array, Western blot analysis, and immunohistochemical analyses.

RESULTS

AQP1, normally restricted to choroid epithelia, was highly expressed in glioblastomas. Complementary deoxyribonucleic acid array, Western blot analysis, and immunohistochemical analysis revealed intense up-regulation of AQP1 expression in all glioblastomas studied.

CONCLUSION

The abnormal up-regulation of AQP1 in glial tumors suggests a potential pathological role for this membrane water channel and raises the possibility that selective AQP1 inhibition might offer a new therapeutic target for treatment of tumor-associated edema.

Reduced cerebrospinal fluid production and intracranial pressure in mice lacking choroid plexus water channel Aquaporin‐1

Aquaporin-1 (AQP1) is a water channel expressed strongly at the ventricular-facing surface of choroid plexus epithelium. We developed novel methods to compare water permeability in isolated choroid plexus of wild-type vs. AQP1 null mice, as well as intracranial pressure (ICP) and cerebrospinal fluid (CSF) production and absorption. Osmotically induced water transport was rapid in choroid plexus from wild-type mice and reduced by fivefold by AQP1 deletion. AQP1 deletion did not affect choroid plexus size or structure. By stereotaxic puncture of the lateral ventricle with a microneedle, ICP was 9.5 +/- 1.4 cm H2O in wild-type mice and 4.2 +/- 0.4 cm H2O in AQP1 null mice. CSF production, an isosmolar fluid secretion process, was measured by a dye dilution method involving fluid collections using a second microneedle introduced into the cisterna magna. CSF production in wild-type mice was (in microl min(-1)) 0.37 +/- 0.04 (control), 0.16 +/- 0.03 (acetazolamide-treated), and 1.14 +/- 0.15 (forskolin-treated), and reduced by approximately 25% in AQP1 null mice. Pressure-dependent CSF outflow, measured from steady-state ICP at different ventricular infusion rates, was not affected by AQP1 deletion. In a model of focal brain injury, AQP1 null mice had remarkably reduced ICP and improved survival compared with wild-type mice. The reduced ICP and CSF production in AQP1 null mice provides direct functional evidence for the involvement of AQP1 in CSF dynamics, suggesting AQP1 inhibition as a novel option for therapy of elevated ICP.

Expression of aquaporin water channels in mouse spinal cord

Aquaporins (AQPs) are membrane proteins involved in water transport in many fluid-transporting tissues. Aquaporins AQP1, AQP4, and AQP9 have been identified in brain and hypothesized to participate in brain water homeostasis. Here we use reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry to describe the expression and immunolocalization of AQPs in adult mouse spinal cord. AQP4 was expressed in glial cells, predominantly in gray matter, and in astrocytic end-feet surrounding capillaries in spinal cord white matter. AQP9 expression extensively co-localized with glial fibrillary acidic protein-immunoreactive astrocytes, located predominantly in the white matter. AQP5 was detected by RT-PCR but not by immunohistochemical analysis. Interestingly, AQP8 was detected primarily in ependymal cells lining the fluid-filled central canal. The aquaporin expression pattern in spinal cord suggests involvement in water homeostasis and diseases associated with abnormal water fluxes such as spinal cord injury and syringomyelia.

Increased seizure threshold in mice lacking aquaporin-4 water channels

Mice deficient in the glial water channel aquaporin-4 (AQP4) show decreased cerebral edema and improved neurological outcome following water intoxication or ischemic challenge. In this report, we tested seizure susceptibility in AQP4 mice. AQP4 mice and wild-type controls were given the chemoconvulsant pentylenetetrazol (PTZ) and monitored for seizure activity. At 40 mg/kg PTZ, all wild-type mice exhibited seizure activity, whereas six of seven AQP4 mice did not exhibit seizure activity. At 50 mg/kg PTZ, both groups exhibited seizure activity; however, the latency to generalized (tonic-clonic) seizures was significantly lower in wild-type than AQP4 mice. These results suggest that glial water channels may modulate brain excitability and the initiation and generalization of seizure activity.

Aquaporin-1 expression in human glial tumors suggests a potential novel therapeutic target for tumor-associated edema

Aquaporins are membrane proteins involved in water transport in many fluid-transporting tissues. The objective of this study was to investigate the expression of aquaporins in malignant glial tumors associated with cerebral edema. Eighteen human glial tumors were obtained from the UCSF Neurosurgery Tissue Bank. Aquaporin-1 (AQP1) expression was evaluated via Western blot and immunohistochemistry. Intense upregulation of AQP1 expression was found in all glioblastomas. The robust expression of aquaporins in glioblastomas suggests a pathologic role for these membrane water channels, and raises the possibility that selective AQP inhibition might offer a new therapeutic option for tumor-associated cerebral edema.

Aquaporin-1 deletion reduces osmotic water permeability and cerebrospinal fluid production

Aquaporin-1 (AQP1) is a water channel that is strongly expressed at the ventricular-facing surface of choroid plexus epithelium. Using wildtype and AQP1 null mice, we developed novel methods to compare the water permeability in isolated choroid plexus, and cerebrospinal fluid (CSF) production in living mice. Osmotically-induced water transport was rapid in freshly isolated choroid plexus from wildtype mice as measured by a spatial-filtering optical method, and reduced by 5-fold by AQP1 deletion. CSF production, an isosmolar fluid secretion process, was measured by a dye dilution method involving fluid collections using a second microneedle introduced into the cisterna magna. CSF production in wildtype mice was (in microl/min) 0.37 +/- 0.04 microl/min (control), 0.16 +/- 0.03 microl/min (acetazolamide-treated) and 1.14 +/- 0.15 microl/min (forskolin-treated), and reduced by up to 25% in AQP1 null mice. The impaired CSF production in AQP1 null mice provides direct functional evidence for the involvement of AQP1 in CSF formation.

Optical measurement of swelling and water transport in spinal cord slices from aquaporin null mice

Water movement between cells and interstitium in spinal cord and brain occurs during neural signal transduction and in response to injuries such as ischemia and blunt trauma. At least two aquaporin-type water channels are expressed in spinal cord: AQP1 in afferent sensory nerve fibers in the superficial layers of the dorsal horn, and AQP4 in glial cells throughout gray matter. An imaging method was developed to map thickness changes in viable spinal cord and brain slices cut by a vibratome, and applied to measure osmotically induced water transport in spinal cord slices from wildtype and aquaporin knockout mice. Spinal cord slices (300 microm thickness) were mounted in a perfusion chamber with < 2 s exchange time, and transmitted light (565 nm) was imaged by a CCD camera. Changes in slice thickness were mapped from the amount of light passing through a thin ( approximately 100 microm) layer of perfusate bathing the slice, in which hemoglobin (6 mg/ml) was added to the perfusate as an inert absorbing chromophore. In response to osmotic challenges imposed by changing perfusate osmolality by 100 mOsm, transmitted light intensity changed reversibly with approximately mono-exponential kinetics whose initial rate depended upon position in the slice. In the superficial dorsal horn where AQP1 is strongly expressed, the rate of osmotic swelling was 7.0 +/- 1.3 microm/s in wildtype mice and 2.0 +/- 0.2 microm/s in AQP1 null mice; osmotic swelling was slower in deeper lamina of dorsal horn, and was decreased in AQP4 but not AQP1 null mice. These results establish a simple imaging method to map changes in water content of spinal cord slices, and provide evidence that aquaporins facilitate osmotic water transport in functionally relevant areas of the spinal cord.

[Fatty liver quantification with line scan echo planar spectroscopic imaging (LSEPSI)]

INTRODUCTION

Although fatty infiltration of liver is a benign process that generally results from chronic alcohol uptake or obesity, such lifestyle factors may lead to chronic disease. Measuring the fat concentration in liver may therefore prove useful in assessing disease status. In this study, we report the usefulness of line scan echo planar spectroscopic imaging (LSEPSI) for this problem.

METHODS

Rapid successive column sampling was accomplished using orthogonal slice-selective 90 degrees and 180 degrees pulses and echo planar spectral/spatial encodings. Phantom and clinical studies of 13 patients suspected of having fatty liver were carried out with LSEPSI. Estimated fat fractions obtained with LSEPSI were compared with ultrasound findings.

RESULTS

The results showed a good correlation between the actual fat content of phantoms and the estimated fat fraction obtained with LSEPSI (r = 0.95). In the clinical study, the estimated fat fraction tended to rise as the US grade of fatty liver increased.

DISCUSSION

LSEPSI is largely free from T1 and T2 relaxation owing to its infinite TR and minimal T2 weighting. Thus, there is no need for relaxation analysis. In addition, the lack of phase encoding reduces motion-related ghosting artifacts. Rapid fat/water spectral quantification of liver with this technique is useful for fatty liver assessment in a clinical setting.

Relaxation effects of clustered particles

Relations between spatial distribution of superparamagnetic iron oxide (SPIO) particles and the image contrast caused by SPIO were investigated. Actual clustering pattern of particles was measured in the liver and spleen of animals using intravital laser confocal microscopy. SPIO-doped phantoms with and without Sephadex beads were made to simulate these patterns, and relaxation parameters were measured using a 1.5-T clinical scanner. Finally, these results were compared to clinical image data using SPIO particulate agent. Intravital microscopy indicated that the clustering of latex beads was more predominant in hepatic Kupffer cells than in splenic macrophages (P < 0.001). Phantoms without Sephadex beads showed an approximately linear increase of 1/T1 (R1), 1/T2 (R2) and 1/T2* (R2*) values with increasing SPIO concentration. However, with Sephadex beads, R1 and R2 showed little change with increasing SPIO concentration, while R2* showed the same linear increase with SPIO. Also, the R2* values were higher with Sephadex beads. These results were consistent with the clinical imaging data, where signal reduction was significantly smaller in the spleen (-0.4% +/- 27.4%) than in the liver (50.4% +/- 16.8%, P < 0.00001) on T2*-weighted images, but the reduction in the spleen (47.2% +/- 16.1%) was equivalent to the liver (38.8% +/- 26.0%) on T2-weighted images.

Temperature monitoring with line scan echo planar spectroscopic imaging

A new magnetic resonance imaging method, line scan echo planar spectroscopic imaging (LSEPSI), is shown capable of providing rapid, internally referenced temperature monitoring from water and fat chemical shifts.

METHODS

Orthogonal 90 degrees and 180 degrees slice selective RF pulses inclined by 45 degrees from the image plane solicit a spin echo from a tissue column. The echo is read by asymmetric sampling of 32 gradient echoes spaced 1.4-1.8 ms apart. Sixty-four adjacent columns are sequentially sampled in 4.2-6.4 s with 4,096 voxels sampled with voxel volumes of 0.08-0.13 cm3. Mixed mayonnaise/water phantoms were used to correlate LSEPSI-derived chemical shifts and thermocouple-based temperature measurements from 23 to 60 degrees C with a 1.5 T scanner. Measurement artifacts unrelated to temperature were investigated with the phantom, as was the feasibility of applying the sequence in human breast in vivo.

RESULTS

The correlation between LSEPSI and thermocouple-based temperature measurements in the phantom was excellent (r2>0.99). Field drifts affecting the temperature measurements using the water peak alone were corrected by using the water/lipid peak difference. The sequence had an average temperature resolution of 1.4 degrees C in the phantom. The frequency difference measurement reduced the sensitivity to artifacts related to temperature. Both water and lipid peaks were detectable throughout many locations in the breast, suggesting the applicability of LSEPSI in this organ.

DISCUSSION

T1-saturation losses occur in conventional and echo-planar based 2D CSI sequences using phase encoding methods with short TR periods. These losses are eliminated when individual columns are sampled in snapshot fashion with LSEPSI since the effective TR becomes the time between scans rather than excitations. T1 saturation can make small spectral peaks difficult to detect at high temperatures and generally lowers the signal-to-noise ratio of the spectra. The rapid acquisition and insensitivity to T1 saturation effects make LSEPSI an attractive technique for monitoring thermal therapies in breast using the internally referenced fat/water frequency separation.

Line scan echo planar spectroscopic imaging

A line scan echo planar spectroscopic imaging (LSEPSI) sequence is presented which can rapidly produce 2D chemical shift imaging (CSI) data with minimal relaxation weighting and motion-related artifacts. The technique is based on successive "snapshot" 1D CSI acquisitions of individual tissue columns, and avoids T(1) saturation problems associated with the short TR periods needed for very rapid scanning with either conventional or echo planar-based 2D CSI methods. Potential applications include rapid fat/water spectral quantitation in the abdomen and internally referenced temperature monitoring for interventional procedures.

vGRASE: separating phase and T(2) modulations in 2D

A new fast imaging technique, vGRASE, was designed and implemented on a clinical imager. In the vGRASE scheme, the T(2) modulation ghost, which is the main problem of the GRASE sequence, can be reduced by separating the phase and T(2) modulations in two encoding directions. Although it is not much faster than the original GRASE, vGRASE has much improved image quality, with the same advantages over RARE and EPI as the original GRASE.

MR-based temperature monitoring for hot saline injection therapy

We applied magnetic resonance (MR) phase mapping methods to monitor the thermal frequency shift of water in order to study temperature changes from percutaneous hot saline injection therapy (PSIT) using in vitro swine livers and in vivo rabbit livers. The thermal coefficients calculated from the shifts of the water frequency with thermocouple based temperature measurements were -0.0085 +/- 0.0019 ppm/ degrees C for the in vitro studies and -0.0089 ppm/ degrees C for the in vivo studies. The error range was estimated to be +/- 3 degrees C and +/- 4.5 degrees C, respectively. Color-coded temperature maps were compared with macroscopic lesion sizes of the specimen. Regions defined using a 20 degrees C elevation in the initial images following hot saline injection (around 55 degrees C in absolute temperature) closely correlated with visible coagulation in size. We conclude that MR temperature monitoring of PSIT is quite feasible and may be helpful in expanding the clinical use of this thermal therapeutic tool for liver tumors.

A preliminary comparative study of the guided tissue regeneration and free gingival graft procedures for adjacent facial root coverage

OBJECTIVE

The purpose of this study was to compare the clinical efficacy of guided tissue regeneration with expanded polytetrafluoroethylene membranes to that of free gingival graft for treatment of adjacent facial gingival recession.

METHOD AND MATERIALS

Eight adjacent gingival recession sites with Miller class I or II defects containing at least a maxillary or mandibular canine were selected in 6 patients. Four recession sites in 3 patients were treated with guided tissue regeneration, and the other 4 sites in the remaining 3 patients were treated with free gingival graft. Probing depth, gingival recession, attachment level, width of keratinized gingiva, and root coverage were recorded before surgery (baseline) and 6 months and 1 year postoperatively.

RESULTS

Statistically significant improvements were found for gingival recession, attachment level, and root coverage from baseline to 6 months and 1 year postoperatively in both groups. Both procedures produced the same average reduction in gingival recession, gain in attachment level, and amount of root coverage after 1 year. Probing depths did not differ between groups throughout the study. The width of keratinized gingiva was significantly greater in the grafted group than in the guided tissue regeneration group.

CONCLUSION

Both procedures produced the same average amount of root coverage, reduction in gingival recession, and gain in clinical attachment. The guided tissue regeneration procedure provided a better esthetic appearance without any difference in gingival color or architecture in cases of adjacent facial gingival recession.

Human brain glucose metabolism mapping using multislice 2D (1)H-(13)C correlation HSQC spectroscopy

A method for multivolume 2D (1)H-(13)C correlation spectroscopy, multislice heteronuclear single quantum coherence (HSQC), is proposed. This permits human brain metabolism from glucose to amino acids to be followed using a 2-T whole-body scanner. The modifications from the conventional HSQC are that the 180 degrees ((13)C) and 180 degrees ((1)H) pulses are separated in time in the preparation period and that the 180 degrees ((13)C) pulse is applied at 1/(4J(CH)) before the 90 degrees ((1)H) polarization transfer (PT) pulse. The preparation (echo) time can be set longer than 1/(2J(CH)) so that, even in a whole-body system, slice-selective pulses and gradients can be applied. Another modification is that the 90 degrees ((1)H) reverse PT pulses after the creation of 2I(z)S(z) are used as multislice pulses. The time-course of glutamate C4 could be followed with 15-min temporal resolution from the HSQC spectra obtained from the brains of volunteers after the oral administration of glucose C1, and the maximum S/N was 3.

3D localized 1H-13C heteronuclear single-quantum coherence correlation spectroscopy in vivo

A method for spatially three-dimensional (3D) localized two-dimensional (2D) 1H-13C correlation spectroscopy, localized HSQC, is proposed. This method has the following special feature in the preparation period. The 180 degrees (13C) and 180 degrees (1H) pulses are separated in time, and the 180 degrees (13C) pulse is applied at 1/4 1JCH) before the 90 degrees (1H) polarization transfer pulse. The preparation (echo) period 2tau can then be set substantially longer than 1/(2 1JCH), so that even in a whole-body system, slice-selective 90 degrees (1H) pulses and gradient pulses can be applied in that period. The localization capabilities of this method were confirmed in a phantom experiment. The 3D localized 2D 1H-13C correlation spectra from a monkey brain in vivo were obtained after [1-13C]glucose injection, and amino acid metabolism was detected; that is, [4-13C]glutamate appeared immediately after the injection, followed by the appearance of [2-13C]glutamate, [3-13C]glutamate, and [4-13C]glutamine.

Temperature mapping using the water proton chemical shift: self-referenced method with echo-planar spectroscopic imaging

An echo-planar spectroscopic imaging method of temperature mapping is proposed. This method is sufficiently faster than the so-called 3D magnetic resonance spectroscopic imaging (3D-MRSI) method and does not require image subtractions, unlike the conventional phase mapping method when an internal reference signal is detectable. The water proton chemical shift measured by using the tissue lipid as an internal reference clearly visualized the temperature change in a porcine liver sample in vitro. It was also demonstrated that the internally referenced echo-planar spectroscopic imaging method could markedly reduce a temperature error caused by a simple, translational motion between scans compared with the phase-mapping method.

Spin-Echo planar spectroscopic imaging for fast lipid characterization in bone marrow

Lipid characterization of bone marrow in vivo with proton magnetic resonance spectroscopy was performed using Spin-Echo Planar Spectroscopic Imaging sequences. The methods are shown capable of rapidly generating two-dimensional chemical shift imaging data sets suitable for measuring lipid indices that reflect unsaturation levels among triglycerides, as demonstrated in oil phantoms and bone marrow from a healthy volunteer. The volume coverage, spatial resolution, acquisition speed, and spectral characteristics of Spin-Echo Planar Spectroscopic Imaging should make it attractive for clinical studies of diseases affecting normal lipid chemical composition.

Selection of high-definition 2D virtual profiles with multiple RF pulse excitations along interleaved echo-planar k-space trajectories

A method for spatially selective excitation of 2D RF profiles is reported. The method makes use of multiple shots to traverse interleaved echo-planar trajectories in 2D k space during each RF pulse excitation. Results from each of the interleaved excitations are summed, with the net effect being the excitation of a virtual profile. The method allows for the excitation of high-definition 2D profiles with standard gradient hardware. Signal to noise is enhanced by a factor equal to the square root of the number of interleaved excitations, compared with a single-shot excitation. Potential applications for volume-localized spectroscopy, functional MRI, and high-resolution reduced-field-of-view imaging are discussed.

In vivo 3D localized 13C spectroscopy using modified INEPT and DEPT

The 3D localized 13C spectroscopy methods LINEPT and LODEPT, which are modifications of INEPT and DEPT, are proposed. As long as a 13C inversion pulse (180-degree pulse) is applied at 1/(4J) before the proton echo time in LINEPT and a 13C excitation pulse (90-degree pulse) is applied at 1/(2J) before the proton echo time in LODEPT, the proton echo time can be set to any value longer than 1/(2J) in LINEPT and longer than 1/J in LODEPT. As a result, the proton and the 13C pulses can be applied separately and these proton pulses can be made slice-selective pulses. These localization features of LINEPT and LODEPT were evaluated using a phantom consisting of a cylinder filled with ethanol placed inside another cylinder filled with oil, and localized ethanol spectra could be obtained. In vivo 3D localized 13C spectra from the brain of a monkey could be obtained using decoupled LINEPT, and glutamate C-4 appeared directly after the administration of glucose C-1, followed by the appearance of glutamate C-2, C-3 and glutamine C-2, C-3, C-4.

Optimization of chemical shift selective suppression of fat

Strategies to optimize flip angles for chemical shift selective fat suppression are discussed. Mathematical models for fat suppression in spoiled gradient recalled acquisition, spin echo, and RARE, which incorporate steady state conditions and multiple spectral components of fat, are developed. The optimal suppression flip angle is found to be larger than that determined with a single fat component model by more than 10 degrees due to contributions from unflipped components such as olefinic and glycerol protons that lie outside the suppression band.

Rapid tip tracking with MRI by a limited projection reconstruction technique

To rapidly track invasive devices within MRI systems, a novel approach using a limited projection reconstruction technique is presented. Our method exploits the difference between images reconstructed from a limited number of projections and serves to depict the tip of a needle during its advancement. This method was implemented on a standard MRI system with a radial fast-spin-echo sequence and examined in phantom studies. We demonstrated that the proposed method could track the tip every 300 msec and the tip depicted by the present technique was consistently displaced along the needle by a small distance (5 mm).

Temperature mapping using the water proton chemical shift: a chemical shift selective phase mapping method

A proton-chemical-shift-based temperature imaging method, called chemical shift selective phase mapping, is proposed. The technique uses frequency-selective suppression to provide frequency selectivity to the phase mapping method. Separate imaging of the phase distributions of the water and nonwater signals reduced the error due to the presence of a nonwater signal in measuring the water proton chemical shift change in two-component samples. Imaging of the phase difference between water and oil yielded an internally referenced water proton chemical shift measurement to visualize the temperature change distribution, which was unaffected by motion-induced susceptibility changes.

In vivo bone marrow lipid characterization with line scan Carr-Purcell-Meiboom-Gill proton spectroscopic imaging

Line scan Carr-Purcell-Meiboom-Gill spectroscopic imaging sequences have been used to extract lipid chemical composition indices in healthy adult bone marrow in the knee at 1.5 T. Since several spectroscopic echo readouts follow each excitation, the information acquired reflects a balance between spectral T2 decay processes and spectral resolution. To examine this balance in detail, data sets with two different echo spacings and spectral resolutions have been acquired to compare the information available from each in studies of bone marrow. Oils for which high field (7 T) proton spectra were recorded were used to evaluate the accuracy of lipid chemical composition indices extracted from the line scan Carr-Purcell-Meiboom-Gill spectroscopic imaging methods at 1.5 T. The extension of the method to fast spectroscopic imaging of bone marrow with multiple echoes is demonstrated.

[The use of high resolution MR imaging for pre-treatment evaluation of breast cancer: detection of intraductal spread]

Thirty-two patients were examined in order to evaluate the role of high-resolution MRI in the treatment planning of breast cancer. A 1.5T Signa imager (GE Medical Systems) was used with dedicated receive-only breast coil. The pulse sequence based on RARE was used with the fat-suppression technique. After examining both breasts with larger FOV (30 cm), the affected breast alone was examined with smaller FOV (18 cm) and larger matrix (512 x 384) with Gd enhancement. Breast cancer showed more prominent and earlier enhancement compared with normal breast tissue. Linear or spotty continuous enhancement from the main tumor was considered to be suggestive of intraductal spread. Of 32 patients, 20 showed linear or spotty enhancement around the main tumor on MRI, and 15 of these 20 had intraductal spread. On the other hand, 12 out of 32 patients were considered to have little intraductal spread on MRI, and these findings corresponded to the pathological findings. Sensitivity, specificity and accuracy of detecting intraductal spread were 88%, 75% and 78%, respectively. In order to evaluate the extent of intraductal spread, further study using more precise correlation with pathology is necessary. High-resolution MRI was also considered to be useful for evaluating the presence of multifocal or multicentric focies or muscle invasion.