Discriminating radiation injury from recurrent tumor with [ 18 F]PARPi and amino acid PET in mouse models

Abstract

Background

Radiation injury can be indistinguishable from recurrent tumor on standard imaging. Current protocols for this differential diagnosis require one or more follow-up imaging studies, long dynamic acquisitions, or complex image post-processing; despite much research, the inability to confidently distinguish between these two entities continues to pose a significant dilemma for the treating clinician. Using mouse models of both glioblastoma and radiation necrosis, we tested the potential of poly(ADP-ribose) polymerase (PARP)-targeted PET imaging with [¹⁸F]PARPi to better discriminate radiation injury from tumor.

Results

In mice with experimental radiation necrosis, lesion uptake on [¹⁸F]PARPi-PET was similar to contralateral uptake (1.02 ± 0.26 lesion/contralateral %IA/cc_max ratio), while [¹⁸F]FET-PET clearly delineated the contrast-enhancing region on MR (2.12 ± 0.16 lesion/contralateral %IA/cc_max ratio). In mice with focal intracranial U251 xenografts, tumor visualization on PARPi-PET was superior to FET-PET, and lesion-to-contralateral activity ratios (max/max, p = 0.034) were higher on PARPi-PET than on FET-PET.

Conclusions

A murine model of radiation necrosis does not demonstrate [¹⁸F]PARPi avidity, and [¹⁸F]PARPi-PET is better than [¹⁸F]FET-PET in distinguishing radiation injury from brain tumor. [¹⁸F]PARPi-PET can be used for discrimination between recurrent tumor and radiation injury within a single, static imaging session, which may be of value to resolve a common dilemma in neuro-oncology.

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Macrophagic myofasciitis: a challenging diagnosis

A 25-year-old man admitted for generalised muscle pain with an insidious onset 3 years ago. He had exercise intolerance and decrease in muscle strength, requiring gait support. He was previously healthy, with no chronic medication or recent history of drugs or toxics. National vaccination plan actualised with hepatitis B and tetanus vaccines administered 10 and 2 years, respectively, before symptom onset. No analytical, imaging or electromyography changes were found. Muscle biopsy revealed an inflammatory infiltrate predominantly macrophagic with aluminium deposits suggestive of macrophagic myofasciitis (MMF). It is probably associated with vaccines previously administered. MMF lesion can be regarded as pathological only if detected at least 18 months after last aluminic immunisation, as our case illustrates.

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Rare glomangiosarcoma of the tongue

The glomus tumour is a rare neoplasm derived from the glomus apparatus. Subungual sites are most common with only three published cases involving the dorsal tongue. To our knowledge, this is the first case of an intraoral malignant glomus tumour (glomangiosarcoma) to be published in English literature. We report a case of a single glomus tumour located on the posterior dorsal tongue of a middle-aged man, which was surgically excised. Immunohistological features were indicative of a glomus tumour; however, in this case, malignant features were also discovered, warranting re-excision.

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Apert syndrome: Be aware of the 'dodgy hip!

Apert syndrome is a rare congenital disorder characterised by craniosynostosis, midface hypoplasia and syndactyly of hands and feet. Here we present a case of a 44-year-old woman, with a genetic diagnosis of Apert syndrome from birth, who presented with symptomatic left-sided hip osteoarthritis secondary to femoral abnormalities. She proceeded to have a total hip replacement. This case report describes the rare occurrence to identify a possible association between Apert syndrome and hip abnormalities.

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Clinical spectrum of Dyke-Davidoff-Masson syndrome in the adult: an atypical presentation and review of literature

Dyke-Davidoff-Masson Syndrome (DDMS) is a rare condition usually diagnosed in paediatric patients with clinical features of hemiparesis, seizures, mental retardation and contralateral cerebral hemiatrophy on neuroimaging. This report follows the case of a 22-year-old man presenting with seizures and hemiatrophy and hemiparesis. On review of cases the most common neuroimaging findings were cerebral hemiatrophy (100%) followed by hemicalvarial thickening (71.4%) and hyperpneumatisation of sinuses (71.4%). Apart from our patient, all nine cases with data on epilepsy control had drug-resistant epilepsy. The onset of seizures in adulthood, block vertebra, short stature, absence of mental retardation and well-controlled epilepsy on monotherapy makes our case exceptional—even bringing to mind the possibility of a DDMS variant. This report exhaustively reviews the wide range of clinical and radiological manifestations of DDMS in the adult, thereby adding to the literature on an unusual syndrome that causes significant neurological morbidity.

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Oropharyngeal paraganglioma presenting with stridor: an unusual presentation

Head and neck paraganglioma is a rare disease to encounter in clinical practice and involvement of the base of the tongue in the oropharynx is yet to be described in the current literature. Although various surgical approaches have been described in the literature, transcervical mandibular swing is an effective technique for adequate exposure and complete excision of the oropharyngeal paraganglioma with adequate control on bleeding especially when it is assisted by coblation.

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A garlic burn

Description 

A 45-year-old woman presented with a 12 hour history of painful blisters and erythema over the dorsum of her left great toe. The patient reported applying freshly sliced raw garlic to the dorsum of her left great toe during the past 4 weeks for up to 4 hours a day to treat a fungal nail infection.

On examination, the left great toe was swollen, erythematous and blistering. Her great toenail was yellow and slightly lifted from the nail bed. Clinically, she had a partial thickness burn and onychomycosis (figure 1). The skin on the toe was pH 9. The toe was irrigated with water until a normal pH was reached, and the blisters de-roofed.

Figure 1

Clinical appearance of garlic burn in this patient. The image shows blistering and erythema consistent with a partial thickness burn. The toenail is discoloured due to the underlying fungal...

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