Hypoperfusion following encephalitis: SPECT with acetazolamide

COVID-19 vaccine is here: practical considerations for clinical imaging applications

Imaging tools are potentially able to provide valuable data regarding the development of an efficient vaccine against viral diseases. Tracking immune cells in vivo by imaging modalities can help us understand the intrinsic behaviors of immune cells in response to vaccine components. Imaging patterns at the vaccination site and draining lymph nodes might provide useful information about the vaccine potency. Besides, serial lung CT imaging has been purposed to evaluate vaccine efficiency regarding its protection against typical lung lesions of viral pneumonias. On the other hand, vaccination causes various confusing radiologic patterns that pose diagnostic challenges for clinicians and pitfalls for reading radiologists. This manuscript reviews potential applications of imaging modalities in the process of vaccine development and also goes over some of the imaging findings/pitfalls following vaccination.

99mTc-HMPAO brain SPECT in the monitoring of cerebral vasculitis therapy

OBJECTIVE

The central nervous system (CNS) may be involved in a variety of inflammatory diseases of the blood vessels, generally known as vasculitis. The clinical diagnosis of such involvement in early stages is difficult, since a mild cognitive impairment can be the only symptom. It was hypothesized that brain-perfusion SPECT would be able to reveal CNS involvement and to monitor the course of the disease. The purpose of this study was assess if and when an improvement of cerebral perfusion can be registered by SPECT during the follow-up of these diseases.

MATERIAL AND METHODS

Eighteen patients affected by Systemic Lupus Erythematosus (SLE), 22 by undifferentiated vasculitis (UV), 5 by Behcet's disease (BD) and 5 by primary Sjogren's Syndrome (pSS) were enrolled in this prospective study. A ^99mTc-HMPAO brain perfusion SPECT was performed before the treatment and was repeated during the follow-up at different time intervals. Image analysis was performed on 10 cerebral areas using a specific software.

RESULTS

In the SLE patients, no significant improvement of brain perfusion was found. On the contrary, in the UV the cerebral uptake of the tracer significantly improved from the twenty-fourth month (18/22 patients). Patients with BD showed an improvement of scintigraphic findings (5/5 patients), while a similar result was obtained only in 2 of the patients with pSS.

CONCLUSIONS

In conclusion, brain SPECT seems to be able to monitor the disease in UV, indicating the moment when an improvement of the cerebral perfusion is achieved. In SLE patients this scintigraphic technique did not show a significant improvement in CNS perfusion.

Pediatric Inflammatory Diseases. Part II: Acute Post-Infectious Immune Disorders

Acute post-infectious immune disorders include Acute Disseminated Encephalomyelitis (ADEM) and its variants such as Acute Hemorrhagic Encephalomyelitis (AHEM), acute necrotizing hemorrhagic leukoencephalitis (ANHLE) of Weston Hurst, multiphasic and recurrent ADEM. Acute Necrotizing Encephalopathy of Childhood (ANE or ANEC) represents a dramatic event, consequent to viral infections, especially Influenza-A, and is now considered different from ADEM. ADEM and variants are classically described as uniphasic syndrome occurring in association with an immunization or vaccination (postvaccine encephalomyelitis) or systemic viral infection (parainfectious encephalomyelitis). However, multiphasic forms are not rare. Pathologically, there is perivascular inflammation, edema, and demyelination within the CNS. Clinical features are focal or multifocal neurologic disorder following exposure to virus or receipt of vaccine. The onset of the CNS disorder is usually rapid and include encephalopathy ranging from lethargy to coma, seizures, and focal and multifocal signs reflecting cerebral and spinal cord involvement. The mortality rate is estimated at 10 to 30 percent, with complete recovery rates of 50 percent cited. Poor prognosis is correlated with severity and abruptness of onset of the clinical syndrome. Multifocal CNS lesions are generally evident on MRI that can be similar from those observed in MS.

Encefalomielite acuta disseminata

L’encefalomielite acuta disseminata (EMAD) è una malattia infiammatoria autoimmune che coinvolge il cervello e il midollo spinale. Descritta soprattutto nel bambino, generalmente fa seguito a un episodio infettivo o a una vaccinazione, ma può essere idiopatica. La sua presentazione clinica comprende un’encefalopatia acuta associata a segni e a sintomi neurologici multifocali. La sua diagnosi si basa sulla clinica e sulla risonanza magnetica, che rivela lesioni multifocali della sostanza bianca in ipersegnale T2 mal delimitate, della stessa età, che prendono il gadolinio e possono anche riguardare il talamo e i nuclei della base. Il liquor può mostrare un’iperlinfocitosi con iperproteinorrachia e, a volte, la presenza di bande oligoclonali transitorie. La sua prognosi è piuttosto favorevole, passato l’episodio monofasico, con un trattamento specifico. È quindi fondamentale escludere fino dall’inizio le sue molte diagnosi differenziali. Il trattamento dell’EMAD, di prima scelta, consiste in boli di corticosteroidi endovenosi a forti dosi. In caso di insuccesso bisogna ricorrere agli scambi plasmatici o alle immunoglobuline endovenose. Anche se, di solito, è monofasica, possono verificarsi altri episodi che fanno allora pensare a un’EMAD multifasica. Tuttavia, in alcuni casi queste nuove poussées sono una modalità di esordio di un’autentica sclerosi multipla.

Acute disseminated encephalomyelitis: clinical and pathogenesis features

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated disorder of the central nervous system (CNS). Disease typically starts with an abrupt onset of neurologic symptoms and signs within days to weeks after a viral infection or immunization. Neuropathological examination of the CNS in ADEM reveals involvement of white matter, with infiltration of monocytoid cells and perivenous demyelination.

Serial magnetic resonance imaging and single photon emission computed tomography study of acute disseminated encephalomyelitis patient after Japanese encephalitis vaccination

We report a 5-year-old mentally retarded Japanese boy who developed acute disseminated encephalomyelitis (ADEM) two weeks after Japanese encephalitis vaccination (Beijing strain). He presented sudden status epilepticus, fever, and disturbance of consciousness. Initial neuroradiological findings revealed multifocal cortical swellings without any white matter lesions, suggesting the existence of partial encephalitis or focal status epilepticus. On the follow-up neuroradiological examinations, small white matter lesions were identified as having gradually extended in spite of clinical improvement by methylprednisolone pulse therapy. The cortical involvement became temporarily worse along with the extension and delayed appearance of white matter lesions. Single photon emission computed tomography (SPECT) showed marked hypoperfusion of cerebral blood flow (CBF) in the cortical lesions at both the acute and the recovery period. The serial neuroradiological findings indicated involvement of white matter and gray matter regions at different stages of the illness and a delay between the onset of symptoms and the appearance of ADEM-associated MR imaging of white-matter lesions.

Serial ultrasound assessment of the basal vein of Rosenthal in HSV encephalitis

Herpes simplex virus encephalitis (HSVE) typically affects the baso-temporal brain. The venous blood drainage of this region mainly occurs via the basal vein of Rosenthal (BVR), which can easily be monitored by transcranial color-coded duplex sonography (TCCS), and might be a useful parameter for the activity of the disease. Serial blood flow velocity (BFV) measurements of the BVR and the basal cerebral arteries were performed in five acute HSVE patients by means of transcranial color-coded duplex sonography (TCCS). Remarkable increased BFV of the BVR at the affected side was found in all patients, showing a maximum within the first 8 d of infection followed by a tendency toward normalisation during the next weeks. In comparison, changes of BFV in the basal cerebral arteries were much more heterogeneous. Our findings suggest that TCCS measurements of the BVR might be used as an additional diagnostic bed-side tool to evaluate patients with HSVE during the acute stage.