Interplay of tau and functional network connectivity in progressive supranuclear palsy: a [18F]PI-2620 PET/MRI study

PURPOSE

Progressive supranuclear palsy (PSP) is primary 4-repeat tauopathy. Evidence spanning from imaging studies indicate aberrant connectivity in PSPs. Our goal was to assess functional connectivity network alterations in PSP patients and the potential link between regional tau-burden and network-level functional connectivity using the next-generation tau PET tracer [¹⁸F]PI-2620 and resting-state functional MRI (fMRI).

MATERIAL AND METHODS

Twenty-four probable PSP patients (70.9 ± 6.9 years, 13 female), including 14 Richardson syndrome (RS) and 10 non-RS phenotypes, underwent [¹⁸F]PI-2620 PET/MRI imaging. Distribution volume ratios (DVRs) were estimated using non-invasive pharmacokinetic modeling. Resting-state fMRI was also acquired in these patients as well as in thirteen older non-AD MCI reference group (64 ± 9 years, 4 female). The functional network was constructed using 141 by 141 region-to-region functional connectivity metrics (RRC) and network-based statistic was carried out (connection threshold p < 0.001, cluster threshold pFDR < 0.05).

RESULTS

In total, 9870 functional connections were analyzed. PSPs compared to aged non-AD MCI reference group expressed aberrant connectivity evidenced by the significant NBS network consisting of 89 ROIs and 118 connections among them (NBS mass 4226, pFDR < 0.05). Tau load in the right globus pallidus externus (GPe) and left dentate nucleus (DN) showed significant effects on functional network connectivity. The network linked with increased tau load in the right GPe was associated with hyperconnectivity of low-range intra-opercular connections (NBS mass 356, pFDR < 0.05), while the network linked with increased tau load in the left cerebellar DN was associated with cerebellar hyperconnectivity and cortico-cerebellar hypoconnectivity (NBS mass 517, pFDR < 0.05).

CONCLUSIONS

PSP patients show altered functional connectivity. Network incorporating deep gray matter structures demonstrate hypoconnectivity, cerebellum hyperconnectivity, while cortico-cortical connections show variable changes. Tau load in the right GPe and left DN is associated with functional networks which strengthen low-scale intra-opercular and intra-cerebellar connections and weaken opercular-cerebellar connections. These findings support the concept of tau load-dependent functional network changes in PSP, by that providing evidence for downstream effects of neuropathology on brain functionality in this primary tauopathy.

Use of PET-CT in diagnostic workup of periprosthetic infection of hip and knee joints: significance in detecting additional infectious focus

Introduction

The diagnosis and management of periprosthetic knee and hip infections as well as the identification and management of possible additional infectious foci is of great importance for successful therapy. This study analyses the importance of ¹⁸F deoxyglucose PET-CT (PET-CT) in the identification of additional infectious focus and subsequent impact on management of periprosthetic infection (PPI).

Material and methods

A retrospective analysis of the clinical data and findings in the period from January 2008 to December 2018 was carried out. One hundred and four patients with in-hospital treatment due to PPI of a hip or knee joint were identified and included in this study. All patients underwent a standardized clinical examination and further surgical and antibiotic therapy. The reevaluation of performed PET-CTs was specifically carried out with regard to the local PPI or detection of secondary foci.

Results

PET-CT successfully verified the PPI in 84.2% of the patients. A total of 78 possible additional foci were detected in PET-CT in 56 (53.8%) of the examined patients. Predilection sites for possible secondary foci were joints (42.3%), pulmonary (15.4%), ear-nose-throat (15.4%), spine (11.5%), and the musculocutaneous tissues (11.5%). Fifty-four positive PET-CT findings were confirmed clinically with need of additional adequate treatment.

Conclusion

PET-CT is a valuable diagnostic tool to confirm periprosthetic joint infection. At the same time, the whole-body PET/CT may detect additional foci of infection with impact on subsequent treatment strategy. PET was of special value in detecting infections at distant locations far from the primary infected joint in significant number. These distant infection locations can be potential cause of a re-infection. This clearly reflects the need of their diagnosis.

Effectiveness of bevacizumab for radiation-induced cerebral necrosis in children

INTRODUCTION

Bevacizumab has been reported to effectively reduce cerebral edema caused by radiation therapy. However, only limited data with a short follow-up in tumor patients are available so far.

PATIENTS AND METHODS

Two children suffering from hemorrhage from arteriovenous malformation (AVM) have been treated with stereotactic radiotherapy and developed radiation-induced cerebral edema with deteriorating neurological status despite maximized steroid therapy. Bevacizumab administration at 5 mg/kg body weight was initiated every 2 weeks.

RESULTS

Bevacizumab treatment rapidly ameliorated the neurological deficits, malignant edema and prevented catastrophic complications. Corticoid therapy could be reduced and discontinued. However, after 18 months, both patients showed identical or worse neurological status than before bevacizumab therapy. AVM radiation therapy had been successful to completely obliterate AVMs.

DISCUSSION

In our limited experience, bevacizumab may be an effective and safe option for rescue therapy for malignant cerebral edema on the basis of radiation-induced necrosis especially in patients who experience rapid deterioration despite corticoid therapy and/or intolerable steroid side effects. Despite the fact that functional improvement could not be achieved in long-term outcome patients significantly stabilized and improved during periods of acute deterioration. In order to determine the long-term effectiveness of bevacizumab further investigation in placebo-controlled studies with a higher number of patients are required.

Preoperative treatment with Botulinum Toxin A before total hip arthroplasty in a patient with tetraspasticity: Case report and review of literature

We report on a patient with tetraspasticity due to perinatal cerebral palsy requiring total hip joint endoprosthesis because of hip dysplasia. In order to minimize the risk of postoperative luxation Botulinum Toxin A was injected preoperatively into hip flexor and adductor muscles guided by CT-fluoroscopy. Outcome measures included muscle tone, limb position and self-reported pain relief. Seven days post injections the tone of the right hip flexor and adductor muscles improved from three to one points on the five-point Modified Ashworth Scale (MAS), the spastic joint position improved from 45° to 20° in flexion and from 20° to 10° in adduction, and the patient was free of pain. Ten days after injection of Botulinum Toxin operation of total hip joint arthroplasty was performed without complication. Improvement of spasticity sustained for another eight weeks. Subsequent Botulinum Toxin A injection three months post surgery resulted in identical results. This case demonstrates a new preoperative indication for Botulinum Toxin A in patients with an increased muscle tone at the hip who have to undergo total hip joint endoprosthesis to reduce the risk of postoperative luxation.

Embolization of experimental wide-necked aneurysms with iodine-containing polyvinyl alcohol solubilized in a low-angiotoxicity solvent

BACKGROUND AND PURPOSE

To evaluate the ready-to-use iodine-containing polyvinyl alcohol (I-PVA) dissolved in the low angiotoxic solvent N-methyl pyrrolidone (NMP) for embolization of porcine wide-necked aneurysms.

METHODS

Fourteen broad-based carotid sidewall aneurysms were surgically constructed in 7 swine. I-PVA (40%) in NMP was injected under temporary balloon occlusion bridging the aneurysm neck. After 4 weeks, follow-up angiography, multisection CT angiography (MSCTA), and 3T MR imaging including MR angiography (MRA) sequences were performed. Afterward, harvested aneurysms were investigated histopathologically.

RESULTS

The liquid embolic was well visible under fluoroscopy and displayed a favorable precipitation pattern, allowing for controlled polymer delivery. Ten aneurysms (71%) were initially completely occluded, whereas in 1 aneurysm, a minimal polymer leakage was observed. The other 4 aneurysms (29%) were almost completely occluded. One animal suffered a lethal rebleeding from the anastomosis after uneventful embolization. Aneurysms embolized with I-PVA could be discriminated well from the parent artery without beam-hardening artifacts on MSCTA, and no susceptibility artifacts were encountered on MR imaging. Histologic examination revealed all aneurysms covered with a membrane of fibroblasts and an endothelial cell layer while a moderate intraaneurysmal inflammatory response to the polymer was observed.

CONCLUSION

I-PVA dissolved in NMP has proved its effectiveness for the embolization of experimental wide-necked aneurysms. This precipitating liquid embolic offers several interesting features in that it needs no preparation before use and no radiopaque admixtures, the latter allowing for artifact-free evaluation of treated aneurysms with MSCTA and MRA. Moreover, it uses NMP as a solvent, which has only a low angiotoxicity.

Organic solvents as vehicles for precipitating liquid embolics: a comparative angiotoxicity study with superselective injections of swine rete mirabile

BACKGROUND AND PURPOSE

The organic solvent dimethyl-sulfoxide (DMSO), as a commonly used vehicle for nonadhesive liquid embolics, is not devoid of local angiotoxic effects. We compared microvascular toxicities of superselective infusions of DMSO with potentially more compatible solvents in swine rete mirabile.

METHODS

Fourteen swine underwent angiography for superselective catheterization of 28 arteries of the rete while electrocardiography and intra-arterial pressure were continuously monitored. The investigated solvents were DMSO, dimethyl isosorbide (DMI), ethyl lactate, glycofurol 75, N-methyl pyrrolidone (NMP), and solketal. Control infusion of saline ruled out catheter induced vasospasm in all cases. Each artery of the rete was infused only once with 0.8 mL of one of the solvents over 60 seconds. Acute angiographic and hemodynamic consequences were evaluated. Blood samples were assessed for signs of intravascular hemolysis. Brains and retia were harvested for gross and histopathologic investigation.

RESULTS

On the basis of the angiographic data, DMSO induced the most pronounced vasospasm with the longest recovery period of all solvents investigated. Ethyl lactate, glycofurol 75, and solketal elicited less severe vasospasms and accordingly resolved much more quickly. DMI and NMP induced only minimal vasospasms with comparably short duration. No solvent caused significant hemodynamic alterations or hemolysis. Gross inspection of brains showed no abnormalities, whereas histopathologic examination revealed mostly nonspecific findings. One rete exposed to solketal displayed possible causal histotoxic changes.

CONCLUSION

DMI and NMP produced far less vasospasm than DMSO. No changes in hemodynamic or hemolytic parameters and no histopathologic findings were observed with infusion of these solvents.

Ultrasound perfusion imaging of cysts in the midbrain

AIM

Cerebral ultrasound perfusion examinations have been focused on the diencephalic plane. We describe perfusion abnormalities in the mesencephalon.

METHOD

Phase-Inversion-Harmonic-Imaging (PIHI, Siemens Sonoline Elegra) was performed in a patient with ponto-mesencephalic cysts, that was defined by MRI. The signal increase (bolus kinetics, SonoVue) was quantified for peak-signal-increase (PSI) and time-to-peak (TTP).

RESULTS

PSI and TTP could be quantified for the ipsi- and contralateral posterior cerebral arteries, the ipsilateral middle cerebral artery, the mesencephalon and the ipsilateral temporal lobe. The contrast agent influx was diminished or extinct in the area of the cysts. PSI and TTP delineated the area of the cystic structure well.

CONCLUSION

PIHI in the mesencephalic plane is feasible and allows identification of pathological structures within the mesencephalon.

Surgical Aspects and Outcome of Delayed Tethered Cord Release

Out of a total of 550 children followed up at our spina bifida center, we report on 81 patients who were reoperated upon for secondary tethered cord syndrome between 1993 and 2000. In four cases with preceding severe progressive scoliosis, untethering was followed by surgical correction and stabilization of curvatures. In 77 patients, the indication for surgery was based on late progressive neurological deterioration. The current clinical relevance of competing etiologic factors such as symptomatic Chiari malformation, hydromyelia, and shunt dysfunction, requiring different clinical management, had been previously carefully excluded. The children underwent magnetic resonance imaging (MRI) or myelo-computed tomography (m-CT) to identify the morphologic extent of tethering and any associated spinal malformations such as dermoid tumors (19 cases) or diastematomyelia (9 cases). Surgery became faster and safer through bilateral dural incision, undercutting arachnoid adhesions along the tethered area, although this procedure increased the need for dural grafting. Complete release of the conus medullaris and cauda equina was achieved in a total of 75 cases (93 %) including those who had undergone prophylactic surgery. A mean follow-up of 4.8 years in 77 patients operated upon for late progressive neurological deterioration confirmed stabilization of presenting symptoms in 65 cases (84 %) with 20 of them (26 %) even showing significant improvement. In 12 patients (16 %), including all cases of incomplete untethering (n = 4), there was further deterioration.

MRI study of human brain exposed to weak direct current stimulation of the frontal cortex

OBJECTIVE

To determine whether weak transcranial direct current stimulation (tDCS), which is an interesting new tool inducing prolonged cortical excitability shifts in humans, induces brain edema, disturbance of the blood-brain barrier or structural alterations of the brain detectable by magnetic resonance imaging (MRI).

METHODS

In 10 healthy individuals, tDCS, which is known to alter cortical excitability for about 1 h, was applied over motor and pre-frontal cortices. contrast-enhanced t1-, t2-, and diffusion-weighted mri was performed immediately before, 30 and 60 min after tdcs.

RESULTS

MRI performed 30 and 60 min after tDCS did not show pathological signal alterations in pre- and post-contrast-enhanced T1-weighted and diffusion-weighted MR sequences.

CONCLUSIONS

tDCS protocols which are known to result in cortical excitability changes persisting for an hour after stimulation do not induce brain edema or alterations of the blood-brain barrier or cerebral tissue detectable by MRI.

SIGNIFICANCE

These results deliver further evidence for the safety of the currently applied tDCS protocols in humans.

[Application of multislice detector spiral computed tomography to intracranial aneurysms: first clinical experience]

PURPOSE

To identify advantages when using the new multislice spiral CT technology (MSCT) for the detection and demonstration of intracranial aneurysms with CT angiography (CTA)?

MATERIAL AND METHODS

Patients with suspected intracranial aneurysms underwent 4- and 8-slice spiral CTA. Image postprocessing included "maximum intensity projection" (MIP),"volume rendering" (VR) and additionally curved multiplanar reconstructions (MPR) for aneurysms suspected at the carotid siphon. The results were compared with those achieved with digital subtraction angiography (DSA).

RESULTS

In 19 patients 21 out of 22 aneurysms were detected by CTA. A high resolution three-dimensional view of the aneurysm morphology in spatial relation to the surrounding structures was achieved. Further information could be gained by making a detailed examination of the inside wall of the aneurysm, using virtual vascular 3D-endoscopy and virtual 3D-craniotomy.

CONCLUSION

Compared to DSA,MS-CTA is a useful additional and in selected cases alternative modality for the detection with marked advantages in the demonstration of intracranial aneurysms.

[Site of a polyurethane stent in dacryocystography. Is postoperative success hereby predictable?]

BACKGROUND

Despite new methods for treating complete stenosis of the nasolacrimal duct dacryocystorhinostomy remains the standard operation. Implanting a nasolacrimal polyurethane stent through the nasolacrimal duct to preserve the natural lacrimal pathway seems to offer alternative procedure with similar success rate and without skin incision and general anesthesia. We examined whether an anatomically correct position increases its success rates.

METHODS

This prospective study included 40 patients (mean age 57 years). The polyurethane stent was implanted during dacryocystography, and its position was checked at follow-up visits after 6 months. In the event of an additional canalicular stenosis a 45-mm-long stent was implanted, in the other patients a 35-mm-long stent.

RESULTS

A dacryocystographically correct position was found in only 21 of 40 patients; in the other 19 the stent did not enter the nose under the inferior concha. However, there was no correlation between correct position under the inferior concha and success rate. In 8 of the 40 patients the stent was not patent.

CONCLUSION

The postoperative success rate cannot be predicted by the radiographic position along the ductus nasolacrimalis.

MRI and 18F-fluorodeoxyglucose positron emission tomography in hemimegalencephaly

We report hemimegalencephaly in a 44-year-old woman with mental retardation, epilepsy and a mild hemiparesis. In addition to typical findings on MRI, 2-deoxy-2[18F]fluorodeoxyglucose positron-emission tomography (PET) demonstrated glucose hypometabolism of the affected hemisphere. The results of PET have been coregistered with morphological information from the MRI studies by image fusion.

[Reversible cyclosporin A-induced leukoencephalopathy: a case report and differential diagnosis discussion]

The pathogenesis of Cyclosporin A (CsA) induced toxic leukoencephalopathy is unclear. CCT and CMRI reveal hypodense respectively hyperintense bilateral and symmetrical changes predominantly in the posterior white matter. We report a patient with a severe CsA induced toxic leukoencephalopathy in whom clinical symptoms (complete loss of brainstem functions, coma) and morphological changes in CCT and CMRI were completely reversible after immunosuppression with CsA has been stopped. We furthermore discuss the differential diagnoses of CCT and CMRI findings.

[Variant of Klippel-Trenaunay syndrome. A case report]

Klippel-Trenaunay-Syndrome is a rare congenital vascular malformation with cutaneous naevi, varicose veins and limb hypertrophy. We report a patient with a variant of this syndrome presenting with extensive varicose veins and arteriovenous shunts within the left arm, bony hypotrophy of the left hand, mucocutaneous melanin spots in the face and thrombocytopenia. Imaging techniques play a major role in making a diagnosis in angiophakomatoses.

[The T2-weighted half-Fourier acquired single-shot turbo-spin-echo technic compared to the conventional T2-weighted turbo-spin-echo technic for cerebral magnetic resonance tomography. A sequence comparison]

PURPOSE

To compare a T2-weighted half-fourier acquired single-shot turbo spin-echo (HF-TSE) sequence (HA-STE-sequence) for cerebral MRI with a standard T2-weighted fast spin-echo (TSE) sequence.

MATERIALS AND METHODS

Signal-to-noise (SNR) and contrast-to-noise ratios (CNR) for different cerebral structures, and intracerebral lesions as well as the detectability of intracerebral lesions depending on size and relaxation properties were evaluated on cranial MR examinations of 46 patients with both a TSE and a HF-TSE sequence.

RESULTS

SNR and CNR were found to be significantly higher with the TSE sequence for all normal structures and lesions except CSF, and lesions with short relaxation time T2 (p < 0.001). The number of detected lesions larger than 10 mm was similar with both sequences. Thirty-six (TSE) and 34 (HF-TSE) hyperintense, and 7 (TSE) and 2 (HF-TSE) hypointense lesions of at least 5 mm but less than 10 mm in size were detected. Thirty-three (TSE) and 10 (HF-TSE) hyperintense, and 2 (TSE) and no (HF-TSE) hypointense lesions smaller than 5 mm were detected.

CONCLUSION

Due to its short acquisition time, the HF-TSE sequence is an alternative for MR examinations of non-compliant or claustrophobic patients. The low SNR and CNR relative to the TSE-technique are limiting factors as to the detectability of small lesions or lesions with low contrast to surrounding structures, with the risk of an increasing number of false negative results in lesions with short T2 relaxation time smaller than 10 mm.

CSF flow studies of intracranial cysts and cyst-like lesions achieved using reversed fast imaging with steady-state precession MR sequences

BACKGROUND AND PURPOSE

Differentiating between intracranial cysts or cyst-like structures and communicating or noncommunicating cysts is often not possible with cranial CT or nonfunctional MR imaging. We evaluated a retrospective ECG-gated fast imaging with steady-state precession (PSIF) MR sequence with optional cine mode to differentiate cystic masses from enlarged CSF spaces and to determine the accuracy of detecting communication between cysts and neighboring CSF spaces.

METHODS

Fourteen patients with intracranial cystic masses underwent CSF flow studies with an ungated and a retrospective ECG-gated cine-mode PSIF sequence in addition to spin-echo imaging. Findings were evaluated retrospectively by using a five-point rating scale and without knowledge of clinical or other imaging findings. Results were compared with intraoperative findings or with results of intrathecal contrast studies.

RESULTS

Eighteen arachnoid cysts and one enlarged cisterna magna were diagnosed. Improved differentiation between cysts and enlarged CSF spaces was obtained with cine-mode PSIF imaging in six lesions (six patients). Increased diagnostic certainty as to communication between cysts and CSF spaces was obtained in 18 cysts (13 patients). Diagnoses were verified by membranectomy in five lesions, by CT cisternography in five lesions, and indirectly by shunting in one cystic lesion. In one case, MR diagnosis was not confirmed by CT cisternography.

CONCLUSION

Cine-mode MR imaging with a retrospective ECG-gated flow-sensitive PSIF sequence contributed to the certainty of communication between arachnoid cysts and neighboring CSF spaces with an accuracy of 90%, using surgical findings or intrathecal contrast studies as reference. Differentiation between intracranial cysts and enlargement of CSF spaces and other cystic masses was improved in 25% of cases.

MRI study of human brain exposed to high-dose repetitive magnetic stimulation of visual cortex

T1-, T2-, and diffusion-weighted MRI was used to determine whether repetitive transcranial magnetic stimulation (rTMS) affects the blood-brain barrier or induces localized brain edema. In 11 healthy individuals, 1,200 to 3,800 stimuli were applied over the visual cortex of one hemisphere in series of 5-, 10-, or 20-Hz stimulus trains. MRI performed 6 minutes to 6 hours after rTMS did not show pathologic changes in conventional MRI sequences, after application of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), or by determining apparent diffusion coefficients.