Computed Tomography Imaging Patterns of Sinonasal Inverted Papillomas: Comparison of Primary and Recurrent Disease

OBJECTIVE

To analyze clinical and radiographic features that may impact the rate of focal hyperostosis (FH) on computed tomography (CT) for primary and recurrent sinonasal inverted papillomas (IPs) as well as highlight factors that may affect concordance between FH and IP true attachment point (TAP).

METHODS

All IPs resected between 2006 and 2022 were retrospectively reviewed. CTs were read by a neuroradiologist blinded to operative details. IP with malignancy was excluded. Operative reports and long-term follow-up data were evaluated.

RESULTS

Of 92 IPs, 60.1% had FH, 25% had no CT bony changes, and 20.7% were revision cases. The recurrence rate for rhinologists was 10.5% overall and 7.3% for primary IPs. Primary and revision IPs had a similar rate of FH (63% vs. 52.6%; p = 0.646) and FH-TAP agreement (71.7% vs. 90%; p = 0.664). Nasal cavity IPs, especially with septal attachment, were more likely to lack bony changes on CT (57.1%) compared to other subsites (p = 0.018). Recurrent tumors were 16 mm larger on average (55 mm vs. 39 mm; p = 0.008). FH (75.0% vs. 60.9%; p = 0.295), FH-TAP concordance (91.7% vs. 74.4%; p = 0.094), and secondary IP (18.8% vs. 20.3%; p = 0.889) rates were similar between recurrent and nonrecurrent tumors.

CONCLUSION

Primary and revision IPs have a similar rate of FH and FH-TAP agreement. Nasal cavity IPs are less likely to exhibit bony CT changes. Lower recurrence was associated with smaller size and fellowship training but not multiple TAPs, revision, FH absence, or FH-TAP discordance.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:1591-1596, 2024.

Role of 18F-Fluorocholine Positron Emission Tomography (PET)/Computed Tomography (CT) in Diagnosis of Elusive Parathyroid Adenoma

Accurate localization of parathyroid adenomas is paramount in hypercalcemia and elevated parathyroid hormone (PTH) levels. This narrative of a 56-year-old female diagnosed with primary hyperparathyroidism underscores the intricacies faced when conventional imaging falls short. Despite a series of diagnostic and surgical endeavors, including an initial nuclear sestamibi scan and diverse imaging examinations like ultrasound, 4D CT, and MRI, it was the 18F-Fluorocholine positron emission tomography (PET)/computed tomography (CT) scan that illuminated the presence of the elusive adenoma in the left para esophageal superior mediastinum. The surgical outcome reinforced the diagnosis, marking the resolution of the adenoma. This case accentuates the necessity of a multifaceted diagnostic methodology, especially in convoluted primary hyperparathyroidism presentations. It highlights the yet-to-be widely adopted 18F-Fluorocholine PET/CT scan, emphasizing its prospective significance awaiting Food and Drug Administration (FDA) endorsement.

Treatment of Metastatic Spinal Disease; what the Radiologist needs to know

Advancements in technology and multidisciplinary management have revolutionized the treatment of spinal metastases. Imaging plays a pivotal role in determining the treatment course for spinal metastases. This article aims to review the relevant imaging findings in spinal metastases from the perspective of the treating clinician, describe the various treatment options, and discuss factors influencing choice for each available treatment option. Cases that once required radical surgical resection or low-dose conventional external beam radiation therapy, or both, are now being managed with separation surgery, spine stereotactic radiosurgery/stereotactic body radiation therapy, or both, with decreased morbidity, improved local control, and more durable pain control. The primary focus in determining treatment choice is now on tumor control outcomes, treatment-related morbidity, and quality of life.

Embryonal tumor with multilayered rosettes: A report of a rare case

The authors report a case of an embryonal tumor with multilayered rosettes (ETMR) in an 18-month-old female infant who presented with gait imbalance and progressive left-sided weakness for 2 months. ETMR is a rare small round blue cell aggressive tumor of the CNS characterized by the amplification of the C19MC region on chromosome 19 (Chr19q13.42). This report in detail the clinical-radiologic and histopathologic workup and diagnosis. Because ETMRs are newly described rare pediatric CNS tumors with only a few reported cases, we aim to document this typical case to add to the existing data on these tumors.

Myxopapillary ependymoma with interval postoperative CSF seeding: A report of an unusual case

Myxopapillary ependymoma (MPE) is a unique slow-growing benign (WHO grade 1) subtype of spinal cord ependymoma arising predominantly in the filum terminale. Despite its benign nature, it occasionally disseminates through the cerebrospinal fluid and metastasizes to distant sites. Here, we report an extremely rare case of MPE with interval CSF seeding and metachronous metastasis in a 47 -year-old female presented as a gradually increasing low back pain for three months with bilateral radiculopathy down to the knees. Magnetic resonance imaging (MRI) showed an intradural extramedullary spinal mass of iso-intense signal to the cord on T1 weighted-images (WIs), heterogeneous, predominantly hyperintense signal on T2WIs with homogenous enhancement after contrast administration. L2 laminectomy with gross total resection (GTR) was performed, and histopathological results confirmed the diagnosis of MPE. Adjuvant radiotherapy was administered, followed by series of MRI scans. 28 months after GTR, Lumbar MRI showed multiple tiny enhancing nodules in the cauda equina. 44 months follow-up whole spine MRI revealed multiple intradural extramedullary nodules throughout the entire spine. The largest one measures about 1.5cm opposite to T3 -T4 intervertebral disc space. The patient underwent T3 and T4 laminectomy and GTR under general anesthesia using microsurgical techniques, and the histopathological result came with the diagnosis of MPE.

Timing of diffusion weighted imaging lesions in spontaneous intracerebral hemorrhage

INTRODUCTION

Diffusion weighted imaging (DWI) lesions are common after spontaneous intracerebral hemorrhage (sICH). However, their timing relative to a patient's admission to the hospital is unknown. The purpose of this study is to estimate the timing of new DWI lesions after admission for acute sICH.

MATERIAL AND METHODS

Select patients enrolled in a single center prospective study examining the prevalence DWI lesions in acute primary sICH received two MRI scans of the brain after admission. The presence of a new DWI lesion between MRI scans was defined as a new DWI event. A lognormal parametric model was used to estimate the median time (50% percentile) to develop a new DWI lesion.

RESULTS

Among the 121 participants enrolled in the study, 63 (52%) had two brain MRIs. The median time from admission to 1st MRI was 1 day (IQR 1.2, range 0.1-8.4). The median time between the 2 MRI scans was 2.1 (IQR 2.9, range 0.02-17.4) days. 30.2% (n = 19) of participants developed a new DWI lesion between MRI scans. The estimated median time from 1st MRI to new DWI event was 6.3 days (95% CI, 4.1 to 9.6).

DISCUSSION AND CONCLUSION

Accounting for time from admission to 1st MRI, we found that 50% of new DWI lesions occurred by 7.3 days after sICH admission. Pathophysiologic changes in sICH during this time frame need to be studied in order to elucidate a mechanism for DWI lesions.

Dural Ectasia and Cauda Equina Syndrome: A Rare Complication of Long-standing Fusion

The clinicoradiological combination of cauda equina syndrome (CES) and dural ectasia is rare and has been described in a few of patients with ankylosing spondylitis (AS). Simultaneous occurrence of these entities in the absence of AS and in patients with long-standing spinal fusion is extremely rare. We present a case of dural ectasia and CES occurring as a long-term complication of instrumented spinal fusion and discuss the pathogenesis, imaging findings, and management options of this elusive disease process.

Isolated Extracranial Vasospasm and Intracranial Dissection: An Unusual Imaging Manifestation of Reversible Cerebral Vasoconstriction Syndrome

Reversible cerebral vasoconstriction syndrome (RCVS) is a distinct clinical syndrome characterized by thunderclap headache and reversible cerebral vasoconstriction. An association between RCVS and arterial dissection has emerged in recent years, where dissection typically involves the cervical vertebral arteries. In this vignette, we describe isolated reversible vasoconstriction, involving the extracranial arteries and intracranial dissection-a combination hitherto never reported.

MR imaging in nelarabine-induced myelopathy

Nelarabine is one of the newer and novel drugs approved by the USA Food and Drug Administration for treatment of relapsed and resistant acute lymphoblastic leukemia. Although there are a few accounts of the neurologic toxicity of nelarabine in the oncological literature, it has never been discussed from a radiologic stand point to our knowledge. We describe a case of nelarabine-induced myelopathy and review the existing literature in an attempt to characterize the MRI features helpful in making an early diagnosis of this elusive entity.

Intrasphenoidal Rathke's cleft cyst

We report a rare patient with an intrasphenoidal Rathke's cleft cyst (RCC) and review the literature. RCC are benign epithelium lined cysts containing mucoid material, which typically occur in a location that is either entirely intrasellar, or intrasellar with suprasellar extension (intra-suprasellar). RCC in a completely extrasellar location are uncommon. An intrasphenoidal RCC is extremely rare with only two patients reported in the literature to date. Preoperative diagnosis is difficult due to the uncommon location and absence of any characteristic radiological features. However, it remains of utmost clinical relevance because it may limit the operative management to biopsy sampling of the cyst wall and drainage of the contents via the transsphenoidal route.

Evaluation of a metal artifacts reduction algorithm applied to postinterventional flat panel detector CT imaging

BACKGROUND AND PURPOSE

Flat panel detector CT images are degraded by streak artifacts caused by radiodense implanted materials such as coils or clips. A new metal artifacts reduction prototype algorithm has been used to minimize these artifacts. The application of this new metal artifacts reduction algorithm was evaluated for flat panel detector CT imaging performed in a routine clinical setting.

MATERIALS AND METHODS

Flat panel detector CT images were obtained from 59 patients immediately following cerebral endovascular procedures or as surveillance imaging for cerebral endovascular or surgical procedures previously performed. The images were independently evaluated by 7 physicians for metal artifacts reduction on a 3-point scale at 2 locations: immediately adjacent to the metallic implant and 3 cm away from it. The number of visible vessels before and after metal artifacts reduction correction was also evaluated within a 3-cm radius around the metallic implant.

RESULTS

The metal artifacts reduction algorithm was applied to the 59 flat panel detector CT datasets without complications. The metal artifacts in the reduction-corrected flat panel detector CT images were significantly reduced in the area immediately adjacent to the implanted metal object (P = .05) and in the area 3 cm away from the metal object (P = .03). The average number of visible vessel segments increased from 4.07 to 5.29 (P = .1235) after application of the metal artifacts reduction algorithm to the flat panel detector CT images.

CONCLUSIONS

Metal artifacts reduction is an effective method to improve flat panel detector CT images degraded by metal artifacts. Metal artifacts are significantly decreased by the metal artifacts reduction algorithm, and there was a trend toward increased vessel-segment visualization.

Hemodynamic changes following wingspan stent placement--a quantitative magnetic resonance angiography study

BACKGROUND

Quantitative magnetic resonance angiography (QMRA) is a noninvasive imaging modality that provides anatomic and physiologic measurements of arteries. We used QMRA to assess hemodynamic changes following Wingspan stent placement for intracranial stenosis.

METHODS

We reviewed patients treated with Wingspan stents for intracranial stenosis who had baseline and follow-up QMRA data. We compared volumetric flow rates (VFRs) (mL/minute) pre- and poststenting using paired t-tests. P<.05 was considered significant.

RESULTS

Among 9 patients (mean age 65.8 years, mean 71% degree of stenosis), lesions were located in the supraclinoid internal carotid arteries in 3, middle cerebral arteries in 3, and intracranial vertebrobasilar arteries in 3. VFR and degree of stenosis were moderately correlated (r=-.670, P=.002). The mean VFR in the stenotic artery increased from 81.2 mL/minute to 133.3 mL/minute (P=.020) or by 64.2% after stenting. Total cerebral blood flow, flow in nonstented vessels, and collateral flow in circle of Willis vessels did not significantly change.

CONCLUSION

We found that QMRA is a promising noninvasive method for the measurement of cerebral hemodynamics following intracranial Wingspan stent placement. Larger prospective studies are needed to confirm our findings.

The Utility of Quantitative Magnetic Resonance Angiography in the Assessment of Intracranial In-Stent Stenosis

Background and Purpose— Noninvasive screening for intracranial in-stent stenosis is often limited by artifact because of the stent or associated coils. We aimed to determine the utility of quantitative MRA (QMRA) as a screening tool for detecting intracranial in-stent stenosis.

Methods— We reviewed 14 patients who had intracranial stent placement with follow-up QMRA and conventional angiography at our institution. Socio-demographic, medical, clinical, and imaging data were abstracted from medical charts. A blinded interventional neurologist reviewed all angiograms for presence of >50% in-stent stenosis. We tested QMRA (mL/min) at varying thresholds as a predictor of angiographic results.

Results— Among 14 patients (mean age, 62 years; 12 female, 2 male), 13 patients had Neuroform stents placed for wide-neck cerebral aneurysms and 1 patient had a Wingspan stent placement for atherosclerotic stenosis. Lesions were located in the intracranial internal carotid artery in 57.2% (n=8), the middle cerebral artery in 14.3% (n=2), and vertebrobasilar arteries in 28.6% (n=4). On follow-up angiography, 2 patients (14.3%) had >50% in-stent stenosis on angiography. Time-of-flight MRA was nondiagnostic in each case because of artifact from the stent or coils. A >20% reduction in vessel-specific blood flow by QMRA was associated with presence of >50% in-stent stenosis on angiography ( P =0.033). As a screening tool to predict >50% angiographic in-stent stenosis, the sensitivity, specificity, positive predictive value, and negative predictive value of QMRA were 100%, 92%, 67%, and 100%, respectively.

Conclusion— We found that QMRA is a promising screening tool to detect intracranial in-stent stenosis. Future prospective studies should focus on whether QMRA has a role in the detection of radiographic restenosis and prediction of clinical events.

Diffusion weighted imaging in heroin-associated spongiform leukoencephalopathy

BACKGROUND

Heroin-associated spongiform leukoencephalopathy (HASL) is a rare complication of heroin abuse. We report a case that highlights the increased sensitivity of diffusion weighted imaging (DWI) compared with T2-weighted imaging in the acute setting of HASL.

METHODS

Single case report.

RESULTS

A 36-year-old male with a history of heroin abuse (snorting) presented with a 3-day history of lethargy. MRI brain revealed restricted diffusion involving the globus pallidum and cerebral cortex bilaterally that was not seen on fluid-attenuated inversion recovery (FLAIR) images. The patient was diagnosed with acute HASL. Repeated MRI FLAIR at 3 months confirmed the development of atrophy and T2 hyperintensity in the subcortical white matter, consistent with leukoencephalopathy. Neurological exam at 3-month follow-up was nonfocal.

CONCLUSIONS

Restricted diffusion, which likely corresponds to electron microscopic findings of fluid entrapment between the myelin lamellae, may be detectable earlier than changes on FLAIR. Clinicians should be aware of the neuroimaging findings of HASL and the increased sensitivity of MRI DWI over T2-weighted images in detecting HASL acutely.

Evidence for a novel functional role of cannabinoid CB(2) receptors in the thalamus of neuropathic rats

Cannabinoid CB₁ receptors have analgesic effects in models of neuropathic pain, but can also produce psychoactive side-effects. A supraspinal location of CB₂ receptors has recently been described. CB₂ agonists are also antinociceptive, although the functional role of supraspinal CB₂ receptors in the control of nociception is unknown. Herein, we provide evidence that CB₂ receptors in the thalamus play a functional role in the modulation of responses of neurons in the ventral posterior nucleus (VPL) of the thalamus in neuropathic, but not sham-operated, rats. Spontaneous and mechanically evoked activity of VPL neurons was recorded with a multichannel electrode array in anaesthetized spinal nerve-ligated (SNL) rats and compared to sham-operated rats. Intra-VPL administration of the CB₂ agonist JWH-133 (30 ng in 500 nL) significantly reduced spontaneous (P < 0.05), non-noxious (P < 0.001) and noxious (P < 0.01) mechanically evoked responses of VPL neurons in SNL rats, but not in sham-operated rats. Inhibitory effects of JWH-133 on spontaneous (P < 0.01) and noxious-evoked (P < 0.001) responses of neurons were blocked by the CB₂ antagonist SR144528. Local administration of SR144528 alone did not alter spontaneous or evoked responses of VPL neurons, but increased burst activity of VPL neurons in SNL rats. There were, however, no differences in levels of the endocannabinoids anandamide and 2AG in the thalamus of SNL and sham-operated rats. These data suggest that supraspinal CB₂ receptors in the thalamus may contribute to the modulation of neuropathic pain responses.

Endocannabinoid metabolism and uptake: novel targets for neuropathic and inflammatory pain

Cannabinoid CB1 and CB2 receptors are located at key sites involved in the relaying and processing of noxious inputs. Both CB1 and CB2 receptor agonists have analgesic effects in a range of models of inflammatory and neuropathic pain. Importantly, clinical trials of cannabis-based medicines indicate that the pre-clinical effects of cannabinoid agonists may translate into therapeutic potential in humans. One of the areas of concern with this pharmacological approach is that CB1 receptors have a widespread distribution in the brain and that global activation of CB1 receptors is associated with adverse side effects. Studies of the endogenous cannabinoids (endocannabinoids) have demonstrated that they are present in most tissues and that in some pain states, such as neuropathic pain, levels of endocannabinoids are elevated at key sites involved in pain processing. An alternative approach that can be used to harness the potential therapeutic effects of cannabinoids is to maximise the effects of the endocannabinoids, the actions of which are terminated by re-uptake and metabolism by various enzymes, including fatty acid amide hydrolase (FAAH), monoacylglycerol lipase (MAGL) and cyclooxygenase type 2 (COX2). Preventing the metabolism, or uptake, of endocannabinoids elevates levels of these lipid compounds in tissue and produces behavioural analgesia in models of acute pain. Herein we review recent studies of the effects of inhibition of metabolism of endocannabinoids versus uptake of endocannabinoids on nociceptive processing in models of inflammatory and neuropathic pain.

Behavioral, central monoaminergic and hypothalamo–pituitary–adrenal axis correlates of fear-conditioned analgesia in rats

Fear-conditioned analgesia is an important survival response which is expressed upon re-exposure to a context previously paired with a noxious stimulus. The aim of the present study was to characterize further the behavioral, monoaminergic and hypothalamo-pituitary-adrenal axis alterations associated with expression of fear-conditioned analgesia. Rats which had received footshock conditioning 24 h earlier, exhibited reduced formalin-evoked nociceptive behavior upon re-exposure to the footshock chamber, compared with non-footshocked formalin-treated rats. Intra-plantar injection of formalin reduced the duration of contextually-induced freezing and 20-40 kHz ultrasound emission. Intra-plantar injection of formalin to non-footshocked, non-conditioned rats did not induce ultrasonic vocalizations. Intra-plantar injection of formalin to footshock-conditioned rats, significantly increased tissue levels of 3,4-dihydroxyphenylacetic acid and the 3,4-dihydroxyphenylacetic acid:dopamine ratio in the periaqueductal gray and reduced levels of dopamine in the thalamus, compared with saline-treated footshocked controls. Non-footshocked, non-conditioned rats were capable of mounting a robust formalin-evoked increase in plasma corticosterone levels. Moreover, plasma corticosterone levels were significantly higher in saline-treated, footshock conditioned rats compared with saline-treated non-footshocked rats and levels did not differ between saline- and formalin-treated footshock conditioned rats. Assessment of the effects of the intra-plantar injection procedure revealed an attenuation of short-term extinction of contextually-induced freezing in rats anesthetized for intra-plantar injection of saline compared with non-anesthetized, non-injected rats as well as discrete effects on monoamines, their metabolites and plasma corticosterone levels. These data extend behavioral characterization of the phenomenon of fear-conditioned analgesia and suggest that measurement of ultrasound emission may be used as an ethologically relevant index of the defense response during fear-conditioned analgesia. Ultrasonic vocalization may also be a useful behavioral output to aid separation of nociception and aversion. The data provide evidence for discrete alterations in dopaminergic activity in the periaqueductal gray and thalamus and for altered hypothalamo-pituitary-adrenal axis activity following expression of defensive behavior.

Effects of direct periaqueductal grey administration of a cannabinoid receptor agonist on nociceptive and aversive responses in rats

The analgesic potential of cannabinoids may be hampered by their ability to produce aversive emotion when administered systemically. We investigated the hypothesis that the midbrain periaqueductal grey (PAG) is a common substrate mediating the anti-nociceptive and potential aversive effects of cannabinoids. The rat formalin test was used to model nociceptive behaviour. Intra-PAG microinjection of the excitatory amino acid D,L-homocysteic acid (DLH) was used to induce an aversive, panic-like reaction characteristic of the defensive "fight or flight" response. Administration of the cannabinoid receptor agonist HU210 (5 microg/rat) into the dorsal PAG significantly reduced the second phase of formalin-evoked nociceptive behaviour, an effect which was blocked by co-administration of the CB(1) receptor antagonist SR141716A (50 microg/rat). This anti-nociceptive effect was accompanied by an HU210-induced attenuation of the formalin-evoked increase in Fos protein expression in the caudal lateral PAG. Intra-dorsal PAG administration of HU210 (0.1, 1 or 5 microg/rat) significantly reduced the aversive DLH-induced explosive locomotor response. The anti-nociceptive effect of HU210 is likely to result from activation of the descending inhibitory pain pathway. Mechanisms mediating the anti-aversive effects of cannabinoids in the PAG remain to be elucidated. These data implicate a role for the PAG in both cannabinoid-mediated anti-nociceptive and anti-aversive responses.