Intraarterial Versus IV Gadolinium Injections for MR Angiography: Quantitative and Qualitative Assessment of the Infrainguinal Arteries

The morphology of balanomorph barnacles during metamorphosis from the cyprid larval stage to the juvenile has been examined by light microscopy and scanning electron microscopy (SEM). The free-swimming cyprid attaches to a substrate, rotates 90° in the vertical plane, molts, and assumes the adult shape. The resulting metamorph is clad in soft cuticle and has an adult-like appearance with a mantle cavity, thorax with cirri, and incipient shell plates. At some time during the development from cyprid to juvenile, the barnacle begins to mineralize its shell, but it is not known whether calcification occurs before, during, or after ecdysis. To examine this issue, electron probe x-ray microanalysis (EPXMA) was used to detect calcium in cyprids and juveniles at various times during metamorphosis.Laboratory-raised, free-swimming cyprid larvae were allowed to settle on plastic coverslips in culture dishes of seawater. The cyprids were observed with a dissecting microscope, cryopreserved in liquid nitrogen-cooled liquid propane at various times (0-24 h) during metamorphosis, freeze dried, rotary carbon-coated, and examined with scanning electron microscopy (SEM). EPXMA dot maps were obtained in parallel for qualitative assessment of calcium and other elements in the carapace, wall, and opercular plates.

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MR Angiography Overused in Assessing Vertigo

Internal Medicine News ◽

10.1016/s1097-8690(06)73063-3 ◽

2006 ◽

Vol 39 (5) ◽

pp. 13

Author(s):

ELAINE ZABLOCKI

Keyword(s):

Mr Angiography

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Time-resolved, contrast-enhanced 3D MR angiography in the subclavian steal effect

VASA ◽

10.1024/0301-1526/a000009 ◽

2010 ◽

Vol 39 (1) ◽

pp. 85-93 ◽

Cited By ~ 1

Author(s):

Schubert

Keyword(s):

Mr Angiography ◽

Time Resolved ◽

Time To Peak ◽

Vertebral Arteries ◽

Subclavian Steal ◽

Cerebrovascular Events ◽

Graphic Analysis ◽

Contrast Enhanced ◽

Hemodynamic Information ◽

Supraaortic Vessels

The subclavian steal effect indicates atherosclerotic disease of the supraaortic vessels but rarely causes cerebrovascular events in itself. Noninvasive imaging providing detailed anatomic as well as hemodynamic information would therefore be desirable. From a group of 25 consecutive patients referred for MR angiography, four with absent or highly attenuated signal in one of the vertebral arteries on 3D multislab time-of-flight MR angiography were selected to undergo 3D time-resolved contrast-enhanced MR angiography. The time-resolved 3D contrast series (source images and MIPs) were evaluated visually and by graphic analysis of time-intensity curves derived from the respective V1 and V3 segments of both vertebral arteries on the source images. In two cases with high-grade proximal left subclavian stenosis, time-resolved 3D ce-MRA was able to visualise retrograde contrast filling of the left VA. There was a marked delay in time-to-peak between the left and right V1 segments in one case and a shallower slope of enhancement in another. In the other two cases, there was complete or collateralised segmental occlusion of the VAs.

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Assessment of extracranial-intracranial bypass in Moyamoya disease using 3T time-of-flight MR angiography: Comparison with CT angiography

VASA ◽

10.1024/0301-1526/a000363 ◽

2014 ◽

Vol 43 (4) ◽

pp. 278-283 ◽

Cited By ~ 8

Author(s):

Qian Chen ◽

Rongfeng Qi ◽

Xiaoqing Cheng ◽

Changsheng Zhou ◽

Song Luo ◽

...

Keyword(s):

Image Quality ◽

Moyamoya Disease ◽

Mr Angiography ◽

Time Of Flight ◽

Consecutive Series ◽

Tof Mra ◽

Bypass Patency ◽

Significant Difference ◽

Contrast Technique ◽

Vessel Integrity

Background: To evaluate the value of time-of-flight MR angiography (TOF MRA) for the assessment of extracranial-intracranial (EC-IC) bypass in Moyamoya disease in comparison with computed tomography angiography (CTA). Patients and methods: A consecutive series of 23 patients with Moyamoya disease were analyzed retrospectively. Twenty three patients underwent 25 procedures of extracranial-intracranial bypass. Cranial CTA was performed within one week after the surgery to assess bypass patency. Then TOF MRA was scanned within 24 h after CTA on a 3T MRI system. Using 5-point scales (0 = poor to 4 = excellent), two radiologists rated the image quality and vessel integrity of bypass for three segments (extracranial, trepanation, intracranial). Results: Image quality was high in both CTA and TOF MRA (mean quality score 3.84 ± 0.37 and 3.8 ± 0.41), without statistical difference (p = 0.66). Mean scores of TOF MRA with respect to bypass visualization were higher than CTA in the intracranial segment (p = 0.026). No significant difference of bypass visualization regarding the extracranial and trepanation segments was found between TOF MRA and CTA (p = 0.66 and p = 0.34, respectively). For the trepanation segment, TOF MRA showed pseudo lesions in 2 of all 25 cases. Conclusions: 3T TOF MRA, a non-contrast technique not exposing the patients to radiation, proved to be at least equal to CTA for the assessment of EC-IC bypass, and even superior to CTA with respect to the intracranial segment. In addition, readers should be aware of a potential overestimation showing focal pseudo lesions of the bypass at the trepanation segment in TOF MRA.

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Coarctation of the abdominal aorta: Demonstration of a rare anomaly using contrast-enhanced MR-angiography

VASA ◽

10.1024/0301-1526.38.1.66 ◽

2009 ◽

Vol 38 (1) ◽

pp. 66-71 ◽

Cited By ~ 2

Author(s):

Schubert

Keyword(s):

Abdominal Aorta ◽

Mr Angiography ◽

Parallel Imaging ◽

Left Renal Vein ◽

Systemic Hypertension ◽

Contrast Enhanced ◽

Younger Age ◽

Maximum Intensity Projections ◽

Collateral Vessels ◽

First Time

We describe a case of aortic coarctation at the level of the infrarenal abdominal aorta which is encountered in less than six individuals in one million. In contrast to aortic narrowing above or including the renal arteries, this seems to be a relatively benign anomaly without systemic hypertension or impaired renal function. For the first time in this type of anomaly, contrast-enhanced MR angiography (ce-MRA) on a multi-receiver channel MR system, with an 8-channel phased array coil and parallel imaging was used. Ce-MRA displayed a tortuous, narrowed aortic segment that was found to be associated with mesenteric artery stenosis and compression of the orthotopic left renal vein, also known as the nutcracker phenomenon. All major aortic branches could be depicted using 3D surface-shaded displays and subvolume maximum intensity projections (MIPs). Collateral vessels of the abdominal wall were identified using whole-volume MIPs. Since the majority of aortic malformations are diagnosed at a younger age, and many suffer from renal insufficiency, we conclude that ce-MRA will eventually place conventional DSA as the modality of choice in malformations of the abdominal aorta.

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