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K D Hagspiel

Publications and source records attributed to K D Hagspiel.

At least 19 recordsLinked to original sources
PubMed2000

The role of spiral volumetric computed tomography in the diagnosis of pulmonary embolism.

To evaluate the evidence for the use of spiral volumetric computed tomography (SVCT) in the diagnosis of acute pulmonary embolism (PE), the 11 English-language studies published through July 1998 that compared SVCT with a reference standard for PE were systematically reviewed. Among the reviewed studies, methodological problems were common. Only 5 of these studies fulfilled 5 of 11 basic standards addressing important issues in diagnostic test research. The reported sensitivities of SVCT compared with pulmonary angiography varied widely (64%-93%), which was likely the result of differences in study populations. Spiral volumetric computed tomography may be relatively sensitive and specific for diagnosing central pulmonary artery PEs, but it is insensitive for diagnosing subsegmental clots. Spiral volumetric computed tomography may have a role as a "rule-in" test for large central emboli, but additional research is required to establish its place in clinical practice.

Acute Disease↗
PubMed2000

Detection of regional pulmonary perfusion deficit of the occluded lung using arterial spin labeling in magnetic resonance imaging.

Detection of regional perfusion deficit in the lung has been demonstrated using an arterial spin labeling technique called flow-sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER). A pulmonary artery was occluded using a nondetachable balloon catheter to simulate an acute pulmonary embolism in 3 of 10 rabbits. Inflating the balloon occludes the artery, and deflating the balloon allows for reperfusion. Perfusion imaging was performed pre-occlusion, during occlusion, and after reperfusion. Signal enhancement due to perfusion of the pulmonary parenchyma was observed in the perfusion images with negligible artifacts. The perfusion deficit of the pulmonary parenchyma was detected distal to the site of occlusion in all three rabbits. Return of the pulmonary parenchymal perfusion was observed after reperfusion. Magnetic resonance imaging using FAIRER can detect signal loss due to absence of perfusion caused by pulmonary embolism.

Animals↗
PubMed2000

NMR of hyperpolarized (129)Xe in the canine chest: spectral dynamics during a breath-hold.

One of the major goals of hyperpolarized-gas MR imaging has been to obtain (129)Xe dissolved-phase images in humans. Since the dissolved-phase signal is much weaker than the gas-phase signal, highly optimized MR pulse sequences are required to obtain adequate images during a single breath-hold. In particular, a solid understanding of the temporal dynamics of xenon as it passes from the lung gas spaces into the parenchyma, the blood and other downstream compartments is absolutely essential. Spectroscopy experiments were performed in the canine chest to elucidate the behavior of xenon exchange in the lung. The experiments covered a time range from 1 ms to 9 s and therefore considerably extend the data currently available in the literature. It was found that the integrals of the dissolved-phase resonances approached plateau values within approximately 200 ms, and then increased again after approximately 1 s. This behavior suggests an early saturation of the parenchyma before xenon reaches downstream compartments. Mono-exponential recovery curves with time constants on the order of 100 ms were fit to the data. These results potentially provide information on several underlying physiological parameters of the lung, including the parenchymal and blood volumes as well as the diffusion properties of lung tissue.

Animals↗
PubMed2000

Imaging pulmonary blood flow and perfusion using phase-sensitive selective inversion recovery.

A technique is described for imaging pulmonary blood flow using a phase-sensitive selective inversion recovery (PS-SIR) sequence. PS-SIR image reconstruction provides excellent contrast, differentiating fully relaxed inflowing blood from inverted blood and lung tissue. The magnetization of the inverted tissues remains negative at any inversion delay less than that at which the magnetization of the lung tissue is nulled, whereas that of the fully relaxed inflowing blood is always positive. Pulmonary blood flow can be observed by tracking the propagation of the pixels with positive values. Five healthy volunteers were imaged. The normal pattern of blood flow advancing from the central arteries toward the peripheries and into the lung parenchyma with return toward the center via draining veins was depicted. The method offers promise for evaluating pulmonary blood flow without the need for image subtraction or contrast administration. Magn Reson Med 43:793-795, 2000.

Adult↗
PubMed2000

Probing lung physiology with xenon polarization transfer contrast (XTC).

One of the major goals of hyperpolarized-gas MRI has been to obtain (129)Xe dissolved-phase images in humans. So far, this goal has remained elusive, mainly due to the low concentration of xenon that dissolves in tissue. A method is proposed and demonstrated in dogs that allows information about the dissolved phase to be obtained by imaging the gas phase following the application of a series of RF pulses that selectively destroy the longitudinal magnetization of xenon dissolved in the lung parenchyma. During the delay time between consecutive RF pulses, the depolarized xenon rapidly exchanges with the gas phase, thus lowering the gas polarization. It is demonstrated that the resulting contrast in the (129)Xe gas image provides information about the local tissue density. It is further argued that minor pulse-sequence modifications may provide information about the alveolar surface area or lung perfusion.

Animals↗
PubMed2000

MR virtual colonography using hyperpolarized (3)He as an endoluminal contrast agent: demonstration of feasibility.

Hyperpolarized gas MR virtual colonography was performed in plastic phantoms and in the dog colon. (3)He was laser polarized in a prototype commercial system. 2D and 3D gradient echo sequences were used to image the noble gas-filled structures. The hyperpolarized (3)He within the plastic tube and colon lumen produced high signal, providing excellent contrast from the surrounding structures. The virtual colonoscopic analysis of the canine dataset allowed visualization of the colonic features and the colonic wall from inside the colon. (3)He colonoscopy is a novel technique to visualize the colon with MRI with the application of an inert gaseous endoluminal contrast agent.

Animals↗
PubMed2000

Lower extremity arteriography with use of iodinated contrast material or gadodiamide to supplement CO2 angiography in patients with renal insufficiency.

PURPOSE: To determine if the use of nonionic contrast material, as compared to the use of gadodiamide to supplement carbon dioxide angiography in patients with peripheral vascular disease (PVD) and chronic renal insufficiency (CRI), results in significant worsening of renal function. MATERIALS AND METHODS: Lower extremity angiographic procedures (diagnostic and diagnostic/intervention) were performed in 40 patients with CRI (baseline serum creatinine [Cr] > 1.5 mg/dL) using CO2 alone or CO2 supplemented with the use of either nonionic contrast material or gadodiamide (up to 0.4 mmol/kg). Serum creatinine levels were obtained before the procedure and at 48 hours after the procedure. The peak Cr level was also determined for patients with a significant (> 0.5 mg/dL) Cr elevation. RESULTS: Forty-two lower extremity angiographic procedures (19 diagnostic and 23 diagnostic/interventions) were performed in 40 consecutive patients from August 1997 to October 1998, with a mean preprocedure Cr of 2.2 mg/dL and a mean postprocedure Cr of 2.4 mg/dL. Twenty-five of the 40 patients (63%) had diabetes mellitus. Fifteen procedures, including six interventions, were performed utilizing CO2 and nonionic contrast material in 15 patients. Six of these 15 patients (40%) demonstrated a Cr increase > 0.5 mg/dL at 48 hours. Seven procedures, including two interventions, were performed with CO2 alone in seven patients. No patients in this group demonstrated an increase in serum creatinine of greater than 0.5 mg/dL at 48 hours. Twenty procedures, including 15 interventions, were performed with CO2 and gadodiamide in 18 patients. In one of these 20 procedures (5%) there was an increase in Cr > 0.5 mg/dL at 48 hours The difference in worsening renal function for the nonionic contrast group (six of 15) compared with the CO2/gadodiamide group (one of 20) was statistically significant (P = .03). When comparing the use of CO2 and nonionic contrast material versus CO2 alone and with gadodiamide (six of 15 versus one of 27), the difference is also statistically significant (P < .01). The average volume of supplemental contrast material was similar in the nonionic contrast material and gadodiamide groups, as was the average volume of supplemental nonionic contrast material in the six patients with an increased Cr. CONCLUSION: The use of small volumes of nonionic contrast material to supplement CO2 angiography in patients with PVD and CRI can be associated with a significant increased risk of worsening renal function when compared to angiography performed with CO2 alone or CO2 and gadodiamide.

Aged↗
PubMed2000

Feasibility of gadodiamide compared with dilute iodinated contrast material for imaging of the abdominal aorta and renal arteries.

PURPOSE: To determine the quality of digital abdominal angiograms obtained with use of full-strength, intra-arterial gadodiamide compared with similar volumes of half-strength iodinated contrast material for evaluating the abdominal aorta and renal vessels. MATERIALS AND METHODS: Twenty-five consecutive patients underwent digital subtraction arteriography of the abdominal aorta performed with equal volumes (32 mL) of either half-strength (300 mg/mL iodine) iodinated contrast material or full strength gadodiamide (0.11-0.25 mmol/kg) to evaluate the abdominal aorta and renal arteries. The contrast agent used was not known to the image readers. The abdominal aorta, left and right renal main renal artery, and first and second order segmental branches were graded separately as diagnostic or nondiagnostic by four angiographers. RESULTS: Images of the abdominal aorta were diagnostic 100% of the time for iodine and gadodiamide, 76% and 80% diagnostic for iodine and gadodiamide in the left main renal artery, respectively; and 100% and 80% diagnostic for iodine and gadodiamide in the right main renal artery, respectively. The first order segmental branches of the right and left renal arteries were graded diagnostic 72% and 56% of the time, respectively, for dilute iodinated contrast material, and 40% and 28% of the time, respectively, for gadodiamide. The second order segmental branches of the right and left kidney were graded diagnostic 24% of the time for iodinated contrast and 8% and 4% of the time, respectively, for gadodiamide. CONCLUSION: Full-strength, intra-arterial gadodiamide at doses smaller than 0.3 mmol/kg can produce diagnostic images of the abdominal aorta and main renal arteries. However, images of the intrarenal branches are usually not diagnostic.

Adult↗
PubMed1999

Perfusion of the kidney using extraslice spin tagging (EST) magnetic resonance imaging.

This study was undertaken to determine whether extraslice spin tagging (EST) perfusion-weighted magnetic resonance imaging is suitable for screening persons for renal perfusion deficits. Six normal and seven patient volunteers with suspected decreased renal perfusion due to renal vascular disease were imaged. X-ray angiograms were also obtained on all patients. The normalized EST signal intensity showed a linear correlation with respect to the percent stenosis measured from the X-ray angiograms. This demonstrates the potential utility of using EST for the evaluation of kidney perfusion, which was done without the need for exogenous MR contrast agents. EST is fast and less expensive than contrast-based methods. These features make EST a candidate for routine screening of patients for renal vascular disease and for the assessment of angiographically equivocal renal artery stenoses. J. Magn. Reson. Imaging 1999;10:886-891.

Adult↗
PubMed1999

Perfusion imaging of the human lung using flow-sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER).

Pulmonary perfusion is an important parameter in the evaluation of lung diseases such as pulmonary embolism. A noninvasive MR perfusion imaging technique of the lung is presented in which magnetically labeled blood water is used as an endogenous, freely diffusible tracer. The perfusion imaging technique is an arterial spin tagging method called Flow sensitive Alternating Inversion Recovery with an Extra Radiofrequency pulse (FAIRER). Seven healthy human volunteers were studied. High-resolution perfusion-weighted images with negligible artifacts were acquired within a single breathhold. Different patterns of signal enhancement were observed between the pulmonary vessels and parenchyma, which persists up to TI = 1400 ms. The T1s of blood and lung parenchyma were determined to be 1.46s and 1.35 s, respectively.

Adult↗
PubMed1999

Renal insufficiency: usefulness of gadodiamide-enhanced renal angiography to supplement CO2-enhanced renal angiography for diagnosis and percutaneous treatment.

PURPOSE: To determine whether gadodiamide is a safe and useful angiographic contrast agent for help in diagnosis and percutaneous treatment of renal artery stenosis in patients with renal insufficiency. MATERIALS AND METHODS: Diagnostic renal angiography and percutaneous renal interventions were performed by using gadodiamide (total dose, 0.3 mmol/kg) and CO2 as intraarterial contrast agents in 25 procedures in 24 patients with renal insufficiency. Serum creatinine levels were obtained within 24 hours before and at 24 and 48 hours after the procedure. Increases in serum creatinine of more than 44 mumol/L were considered clinically important. Gadodiamide-enhanced angiograms were compared with CO2-enhanced angiograms. RESULTS: In 23 (92%) of 25 procedures, there was no increase in serum creatinine level at 48 hours. One patient with acute and chronic rejection of a renal transplant and one with evidence of cholesterol embolization had a clinically important increase in serum creatinine level at 48 hours. No marked increase in creatinine level was observed in patients with relatively low baseline levels (n = 19). Gadodiamide-enhanced angiograms appeared to be better than CO2-enhanced angiograms for help in identifying renal artery occlusions, visualizing renal vessels incompletely filled with CO2, and determining the progress of intervention. CONCLUSION: Gadodiamide appears to be a safe and useful intraarterial contrast agent in patients with renal insufficiency and can be used to supplement or confirm CO2-enhanced angiographic findings.

Acute Disease↗