radiología en la red: Herpes Simplex Encephalitis

Estándar
6 months old child diagnosed with Herpes Simplex Encephalitis (HSE). CT showing low density areas in both temporal lobes. This finding is difficult on CT due to artefacts often present in middle cerebral fossa. Clue here is the coronal reconstruction showing low density in the lower parts of the basal ganglia.
MR in acute phase confirms diffusion restriction bilateral in the lower parts of the basal ganglia as well as oedema seen on T2.
T2 and FLAIR show diffuse oedema in the lower parts of basal ganglia on both sides. 
Follow up MR about 3 months later showing on FLAIR and T1 extensive atrophy and gliosis in the temporal lobes. 
Axial SWI showing extensive hemorrhagic changes (hemosiderin) in the HSE damaged regions. Note extensive encephalomalacia involving temporal lobes and lower parts of basal ganglia.
Teaching point here is to have an extra careful look at CT images that are mostly performed as first line of examination, especially look for oedema and low density in both temporal lobes, lower parts of basal ganglia and the limbic system. It is recommended to perform MR study for further diagnosis. I older patients infarction is the main differential diagnosis. HSE is mostly bilateral and often asymmetric.  

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radiología en la red: Systemic Mastocytosis

Estándar

Systemic mastocytosis (SM) refers to mast cell infiltration in extra-cutaneous tissues. The symptoms of systemic mastocytosis are due to degranulation of mast cells and/or accumulation of mast cells in target organs.

Degranulation of mast cells

Symptoms can be caused by secretion of the following factors:

  • Histamine: Pruritus, urticaria, hypotension, gastric hypersecretion, bronchoconstriction.
  • Heparin: Local anticoagulation, osteoporosis
  • Leukotrienes: Bronchoconstriction
  • Prostaglandins: Bronchoconstriction, flushing
  • Platelet-activating factor:
  • Proteases:
  • Tumor necrosis factor:

Accumulation of mast cells in organs

Accumulation of mast cells in organs can cause organ dysfunction. The so-called B findings refer to organ involvement without organ dysfunction. C findings refer organ involvement with organ dysfunction. The example above shows hepatic involvement with cirrhosis (white arrow) and ascites (yellow arrow) and nodal involvement with bulky adenopathy (red arrow). We also have involvement with diffuse sclerosis. Interestingly, the non-radiology literature stresses the more common osteoporosis, with scarce mention of the sclerosis that tends to dominate the radiology literature.

Diagnosis systemic mastocytosis

The diagnosis of SM requires either, 1 major and 1 minor OR 3 minor criteria. Warning: Boring for radiologists

The one major criterion is: Multifocal, dense infiltrates of mast cells (≥15 mast cells in aggregates) in sections of bone marrow and/or other extra-cutaneous organ(s).

Minor criteria are:

  • Bone marrow or other extra-cutaneous organs: >25% of mast cells in the infiltrate are spindle-shaped or have atypical morphology, or of all mast cells in bone marrow aspirate smears, >25% are immature or atypical.
  • Activating point mutation at codon 816 of KIT in bone marrow, blood, or another extra-cutaneous organ.
  • Mast cells in bone marrow, blood, or other extracutaneous organs express CD2 and/or CD25 in addition to normal mast cell markers.
  • Serum total tryptase persistently > 20 mg/mL (unless associated w clonal myeloid disorder).

Subtypes

  • Indolent (ISM): No C findings
  • Smoldering (SSM): 2+ B findings, no C findings
  • Aggressive (ASM): C findings, no MCL features*
  • Mast cell leukemia (MCL): BMBx diffuse infiltration by atypical, immature mast cells. Aspirate smears ≥20% mast cells.
  • SM with associated hematologic neoplasm (SM-AHN): SM + MDS, MPN, AML, lymphoma, other

References

Akin C, Gotlib J. Systemic mastocytosis: Determining the subtype of disease. UpToDate http://ift.tt/2kVQi11

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caso 30: endofuga tipo II a través de la AMI

Estándar

retomamos el caso que dejé colgado.

teníamos un paciente que había sido intervenido de un aneurisma aórtico abdominal colocándole una endoprótesis.

pasados unos días comienza con dolor abdominal súbito.

en el angioTC abdominal aparece un depósito de contraste en el interior del aneurisma y fuera de la endoprótesis.

esto nos debe hacer pensar en la aparición de una de las complicaciones más graves tras esta cirugía: la aparición de una endofuga.

la endofuga es una emergencia porque predispone de nuevo a la rotura del anuerisma poniendo en riesgo la vida del paciente.

endofugas las hay de varios tipos: I, II, III, IV y V, según por donde se introduce el contraste en el aneurisma.

en este caso, se identifica un vaso saliendo del aneurisma, en su cara anterior, en relación con la endofuga.

¿y cuál es ese vaso?….¡¡muy bien!!: es la arteria mesentérica inferior.

esto es una endofuga tipo II.

En este tipo existe un flujo retrógrado en una de las ramas que salen del aneurisma (en este caso la arteria mesentérica inferior) y que introduce sangre dentro de él, facilitando su rotura.

el paciente se reintervino objetivando el reflujo a través de la AMI, la cual se seccionó y el paciente (y su rectosigma) sobrevivieron.

 

bibliografía recomendada:

1.- Imaging and management of complications of open surgical repair of abdominal aortic aneurysms

Clinical Radiology 67 (2012) 802-814

2.- Endofugas o Endoleaks en Prótesis Endovasculares de Aneurismas de Aorta Abdominal: Lo que el Radiólogo debe saber en relación al Diagnóstico, Caracterización y Principios Básicos de Manejo.

XXXI Congreso Nacional de la SERAM

 

radiología en la red: Brain atlas advances MRI exploration

Estándar

The Gibby-Cvetko atlas is designed to segment the brain into finite anatomic regions with a resolution of 1 mm3 or less to correct for variations in the brain sizes of patients and better delineate the location of cortical structures and skull morphology.

 

“Having a high-resolution, interactive, quantitative brain atlas that we warp to fit the patient and run inside a PACS improves accuracy and speed of reading fMRI studies,” said co-developer Dr. Wendell Gibby, an adjunct professor of radiology at the University of California, San Diego. “It is a big step toward routine utilization of fMRI in clinical practice.”

 

Mapping history

 

Thousands of research studies have been performed using fMRI to explore the living brain and how different regions affect human behavior, diseases, addictions, and dysfunction. However, Gibby and colleagues acknowledge that fMRI has its limitations and has been difficult to adopt in routine clinical practice.

 

“In order to quantitate the activation of a patient, the brain must be segmented into anatomic areas so that the same area can be compared in control patients,” he explained. “You must compare apples to apples. Each human brain is a little different. To do that, we need to coregister the 3D data of my patient’s brain and correlate it to a known standard.”

 

The concept of brain mapping dates back to 1967, when two French neurosurgeons, Drs. Jean Talairach and Gabor Szikla, created a coordinate system from a standardized grid of anatomy slides using internal landmarks of the brain.

 

“The concept behind their coordinate system was based on individual brains that were internally proportional so they could be mapped despite variations in size, and that the coordinate system could take into account those size differences,” said atlas co-developer Dr. W. Andrew Gibby, chief resident in radiology at George Washington University in Washington, DC, who detailed the technology at RSNA 2016.

 

Talairach and colleagues had improved the atlas by 1988 using MR images of a 60-year-old woman. Back then, MRI slice thickness ranged from 2 mm to 5 mm, but the researchers still crafted a 3D atlas from the collected data.

 

“The limitations were that it was done on a single brain, there were variations of slice thickness, and it was relatively low resolution,” W. Andrew Gibby told RSNA attendees.

 

MNI 152 template

 

In 1992, the Montreal Neurological Institute (MNI) advanced brain-mapping technology by performing MRI scans of 2-mm thickness on 240 healthy subjects. MNI researchers adapted the data to combine their results with Talairach’s 3D atlas. The new configuration, known as the MNI 152 template, was then used to map 305 normal subjects with 1-mm MRI slices. A linear algorithm also helped reduce the adverse effects of manual errors and other variables to create sharper 3D images.

 

“The downside was some lack of detail in the cerebellum,” W. Andrew Gibby said.

 

Still, the MNI 152 template played an instrumental role in the creation of the Gibby- Cvetko atlas, which also carries the name of co-developer Steve Cvetko, PhD, vice president at RIS/PACS firm Novarad. The researchers analyzed high-resolution images of 152 right-handed people with normal brains and modified the MNI 152 template to map standard cortical regions of the brain with 1-mm resolution.

 

“We tried to take the MNI 152 dataset and obviate the need to map back into the Talairach coordinates and create a new atlas based on that dataset,” W. Andrew Gibby said. “To do this, we subdivided the idealized brain from the MNI 152 template and used manual demarcation of the cortical regions, which were subsequently segmented using prescribed algorithms to subtract white matter, eliminate overlapping, and ensure that all gray matter was covered.”

 

With the addition of automated scalp stripping and deformable autoregistration, the researchers segment both control data and patient images to compare anatomic areas of the brain. Real-time interaction with the brain atlas also allows physicians to locate activity at any time.

 

Gibby-Cvetko atlas segments the fusiform gyrus within the hippocampus

The Gibby-Cvetko atlas segments the fusiform gyrus (green) within the hippocampus (purple). Image courtesy of Dr. Wendell Gibby.

 

 

To further explain how the atlas works, Wendell Gibby gave the example of viewing the Broca area of the brain, which is linked to speech. The first task is to find the Broca area in 3D and segment the region to quantify its activity.

 

“To do that, we need to coregister the 3D data of my patient’s brain and correlate it to a known standard,” Wendell Gibby said. “The atlas allows real-time interaction. Just click anywhere on the brain, and it will highlight it and show you exactly where you are.”

 

Given that ability, the researchers believe the Gibby-Cvetko atlas can be used for clinical MRI applications and as a teaching tool. It is also adaptable to a DICOM format with a standard PACS. The atlas is available at www.globalrad.org free of charge.

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