CT confirms extent of lung involvement in H1N1 pneumonia

Severe H1N1 pneumonia has a distinct imaging signature, according to University of California, Los Angeles researchers, who presented their work at the Society of Critical Care Medicine meeting earlier this month in Houston.

In the largest analysis to date of severe H1N1 pneumonia requiring intensive care, the team found that all 18 patients had abnormal radiographic and CT findings. In addition, 100% of the patients had ground-glass opacities and consolidation on CT on admission to intensive care units (ICUs).

Dr. Nader Kamangar, a pulmonary and critical care specialist at Olive View-UCLA Medical Center; Dr. Cecilia Jude, a thoracic radiologist; and several fellows and residents conducted the retrospective study of patients during the 2009 H1N1 pandemic.

"Compared to prior studies of H1N1 patients requiring intensive care, this study demonstrated a higher rate of ground-glass opacities and greater involvement of middle and lower lung zones," Jude noted.

All 18 individuals were admitted to the ICU with a primary diagnosis of H1N1. Their ages ranged from 23 to 62 years (mean 41). Each had chest x-ray on admission, and five also had a CT scan.

The diagnosis was confirmed in each patient with either a rapid influenza detection test or a real-time reverse transcriptase polymerase chain reaction assay. Twelve (67%) of the patients met the criteria for acute respiratory distress syndrome and required mechanical ventilation. Three (25%) of these individuals died.

On chest x-ray, 16 (89%) of the patients had ground-glass opacities, 16 (89%) had consolidation, and six (33%) had reticular opacities. Seventeen (94%) patients had bilateral radiographic abnormalities.

The abnormalities involved primarily the middle (78%) and lower (100%) lung zones. Sixteen (89%) had extensive chest x-ray abnormalities involving three or more lung zones. The team also found pleural effusions in 16 (89%) patients.

The most common CT findings were consolidation and ground-glass opacities, seen in all patients. All the CT abnormalities were bilateral and extensive, involving three or more lung zones.

Original link

7T MRI protocol shows brain plaques in MS patients

A new study published online February 20 in Archives of Neurology suggests that 7-tesla MRI with a specialized protocol is highly sensitive for detecting plaques in white and gray brain matter in patients with multiple sclerosis (MS).

German researchers used 7-tesla MRI with a T1-weighted magnetization-prepared rapid acquisition and multiple gradient echoes (MPRAGE) technique. They found that the protocol "clearly delineated every cortical lesion" that was visualized by any other MRI sequence at 1.5-tesla or 7-tesla. The lead author of the study was Tim Sinnecker, from the NeuroCure Clinical Research Center at Charité Medical University in Berlin.

T2-weighted MRI is often used to quantify accumulated MS lesions in the brain, while T1-weighted sequences are used to differentiate, among other things, irreversible brain tissue damage commonly called black holes, the authors wrote. Black holes are associated with the progression of MS and cerebral atrophy. On spin-echo T1-weighted images, a proportion of T2 hyperintense lesions (black holes) appears hypointense to the surrounding normal-appearing white matter for a long time, the group added.

The study included 20 patients with relapsing-remitting multiple sclerosis from the outpatient clinics of the NeuroCure Clinical Research Center. There were 11 male and nine female patients with a mean age of 42 years and mean disease duration of 3.1 years (range, 0.5 to 14.4 years).

For comparison purposes, 14 healthy control subjects also were enrolled. All 34 subjects underwent brain scans with a 7-tesla MRI scanner (Magnetom, Siemens Healthcare), using a 24-channel head coil. In addition, a subgroup of 18 patients with MS received brain scans with a 1.5-tesla scanner.

The imaging protocol included 2D T2-weighted fast low-angle shot (FLASH) and turbo inversion recovery magnitude (TIRM) sequences. For 3D T1-weighted imaging, the researchers used the MPRAGE sequence.

A reader blinded to the data independently evaluated each sequence. In a second study, all detected lesions were retrospectively analyzed in a side-by-side comparison of all sequences.

The analysis found that 7-tesla MPRAGE detected a total of 728 lesions, compared with 584 lesions with 7-tesla FLASH and 399 lesions with 1.5-tesla MPRAGE.

In addition, 7-tesla T2-weighted FLASH discovered 604 cerebral lesions in the patients with relapsing-remitting MS, with a mean of 30.2 lesions per patient. No lesions were discovered among the healthy controls.

Cortical pathology was visible in 10 patients, with the detection of six cortical lesions and 37 leukocortical lesions. Within the 7-tesla acquisitions, each lesion detected at T2-weighted sequences was also visible on corresponding MPRAGE sequences in the side-by-side analysis. At 1.5-tesla MRI, the MPRAGE images found only 452 of 561 lesions (80%) in T2-weighted sequences.

7-tesla MPRAGE was also beneficial regarding the 217 T1 hypointense lesions detected in the MS subgroup. The images showed that each lesion persisted without major change in formation or size for at least one year, and could be classified as a black hole.

T1-weighted MPRAGE at 7 tesla is "highly sensitive" in detecting multiple sclerosis plaques within white and gray brain matter, and the technique depicted structural damage in each lesion, Sinnecker and colleagues concluded.

Original link

X-ray identifies chronic rhinosinusitis in most children

March 15, 2011 -- In challenging cases of suspected chronic rhinosinusitis in children, CT scans represent the gold standard used to make a definitive diagnosis. But a conventional x-ray should be the first exam ordered because it works for the majority of cases, according to an article in the European Annals of Allergy and Clinical Immunology.

Chronic rhinosinusitis, a condition causing nasal blockage, nasal discharge, facial pain, headaches, and/or a reduced or absent sense of smell, is defined as lasting more than 12 weeks in duration. Medical treatment of this condition differs from persistent rhinitis, but the two can be challenging to differentiate.

When diagnostic imaging is needed to supplement fiber-optic nasopharyngeal endoscopy, CT or MRI is usually performed. The images produced by either type of scan are superior to an x-ray image. CT of the paranasal sinuses provides superior resolution of bone and soft tissue and removes superimposed, overlapping structures present in a conventional x-ray. Virtual endoscopic images can also be produced using 3D software.

The advantage of an MRI exam, in addition to eliminating radiation dose exposure to children, is that it provides a very detailed assessment of soft tissues, which helps define the characteristics and extent of inflammation. Unlike CT, it has the capacity to differentiate sinus opacification.

So why order a plain radiograph first? It's an inexpensive exam, x-ray equipment is readily available, and the x-ray image produced is good enough to make a diagnosis for the majority of cases.

Original link

High-pitch chest CT captures fast-moving babies

March 6, 2011 -- VIENNA - High-pitch chest CT is a robust technique that provides high-quality thoracic images of babies in motion -- quickly, without sedation, and at low radiation doses -- according to a study presented at the European Congress of Radiology (ECR).

Still, high-pitch dual-source CT also comes with more overranging, so the resulting greater anatomic coverage edged those high-pitch radiation doses higher than they would have been using a comparable conventional CT system, and were in fact equivalent to it, the results showed.

Using CT in young children, "sedation or intubation is required to improve image quality, particularly in patients who are small and cannot comply with instructions," said Dr. Michael Lell, from University Clinic in Erlangen, Germany. "So our aim was to transfer the [high-pitch CT] protocol that we know from cardiac scanning to the pediatric population."

The study of 60 young patients (31 male, 30 female, mean age 15 months) examined with thoracic CT included 30 scanned using a high-pitch dual-source CT protocol (Definition Flash, Siemens Healthcare) and 30 scanned using conventional low-dose helical CT (Sensation 10 or 64, Siemens Healthcare). There was free breathing during the scans and no sedation.

• Conventional CT images were acquired using pitch of 1.3, 10 or 64 x 0.6-mm collimation, 80 kV (100 kV for > 10 kg body weight), 50 effective mAs, and 0.75-mm reconstruction interval.
• Dual-source CT images were acquired in either single- or dual-source mode using pitch of 1.3 or 3.0, 128 x 0.6-mm collimation, 80 kV, (100 kV for > 10 kg body weight), and 0.75-mm reconstruction interval.

Using a standard soft-tissue edge-enhancing kernel, image quality was assessed using a four-point scale (0 = no artifacts, 3 = severe artifacts), and comparative dose expressed in CTDI_vol and organ doses.

Radiation dose (mSv) Organ 64-detector CT (pitch 1.3) Conventional pitch mode DSCT (pitch 1.3) High-pitch mode DSCT (pitch 3.0) Bone 4.25 3.56 3.82 Heart 4.99 4.49 4.66 Lung 2.2 1.88 1.91 Soft tissue 1.25 1.25 1.31 Average 3.17 2.79 2.92

The average radiation dose was 1.9 ± 0.6 mSv for conventional CT and 1.9 ± 0.6 mSv for high-pitch-mode dual-source CT. The mean scan time was 0.49 seconds in high-pitch mode and from 3.5 to 7.6 seconds using conventional CT.

Doses did not differ significantly between the scanning techniques, and, in particular, images acquired using high-pitch DSCT did not yield lower radiation doses "due to the broader range of overscanning -- the area that we irradiate but do not reconstruct," Lell said.

However, image quality was superior using high-pitch mode owing to a significant reduction in motion artifacts compared to 10- and 64-detector-row conventional CT, he said.

Image quality comparison Image artifacts High-pitch mode DSCT (No.) Conventional CT (No.) No artifacts (image quality = 0) 24 0 Minor artifacts (image quality = 1) 4 9 Marked artifacts (image quality = 2) 2 11 Severe artifacts (image quality = 3) 0 10

Among patients scanned with conventional CT, artifacts were seen at the level of the diaphragm (100%), the borders of the heart (100%), the ribs (67%), and spine (20%). In the high-pitch mode artifacts were seen in only six patients in the lung parenchyma, next to the diaphragm or the heart (p < 0.001), the authors wrote in their abstract.

"We can obtain excellent image quality without any sedation at very low radiation exposure with high-pitch mode, and this turns out to help a lot in terms of workflow because we do not have to call in the patients before in order to get them in contact with the anesthesiologist," Lell concluded. "There's no comorbidity because of this intubation or sedation, and there is no follow-up period so this imaging can be performed on an outpatient basis."

Due to these advantages, the study team uses high-pitch mode on all of its very young patients, he said.

In response to a question from the audience, Lell said the proximal coronary arteries could be seen using the technique, but a full evaluation of the coronary arteries isn't possible due to high heart rates that typically range from 100 to 120 bpm.

Original link

First Confession!

Well, I'm a Radiologist - or should I say 'Radioholic' - and "gadget guru" & "net nerd" of the highest order :) I'm trying to do something new and bring forth a few glimpses of my profession and passion to anybody & everybody who cares to listen - or browse :)


HAPPY BROWSING FOLKS....