Increased Contrast Enhancement Research Articles

Pseudoprogression (PsPr) after concurrent radiotherapy (RT) and temozolomide (TMZ) for newly diagnosed glioblastoma multiforme (GBM)

2025 Background: Increased contrast enhancement on brain imaging following chemoradiotherapy is often interpreted as progression of disease (PD). However, there is growing evidence that radiographic and even clinical worsening may result from effects of therapy, i.e. PsPr, rather than from true PD. Methods: 80 patients (pts) with GBM were treated in an IRB-approved phase 2 clinical trial with concurrent RT and TMZ followed by adjuvant TMZ. MRI was performed post-RT. PsPr was defined as increased contrast enhancement on the initial post-RT MRI scan that improved without changing chemotherapy, or as histologically documented necrosis. True PD was defined as continued progression on subsequent scans, or histologically documented viable tumor. MR perfusion imaging with relative cerebral blood volume (rCBV) and FDG PET imaging were collected in subsets of patients. Results: There were 33 pts with increased enhancement on the initial post-RT MRI; 8 (24%) had PsPr, 17 (52%) had true PD, and 8 (24%) discontinued TMZ (PsPr vs. true PD unknown). Of the 8 pts with PsPr, 2 had MR perfusion scans; both demonstrated increased rather than decreased rCBV. Two others had FDG PET scans; both showed hyper- rather than hypometabolism. Of the 17 patients with true PD, 5 had MR perfusion scans: 4 had increased rCBV and 1 had decreased rCBV; none had PET scans. The single patient with histologically documented PsPr had at the time of surgery, after 2 cycles of adjuvant TMZ, both increased rCBV and hypermetabolic PET scan; perfusion imaging was not performed with his first post-RT MRI. 6 of the 8 pts with PsPr were clinically worse at their post-RT visit; 7 of the 17 with true PD were clinically worse. Conclusions: At least 24% of our pts with increased contrast enhancement post-RT had PsPr; the incidence could be as high as 48% if all 8 pts who discontinued TMZ for a worsening scan actually had PsPr. MR perfusion, FDG PET, and clinical status were not predictive of PsPr versus true PD. It may be reasonable to consider findings on the post-RT MRI as a new baseline, rather than an assessment of response to chemo-RT, because of the high (24–48%) risk of PsPr. This approach would also minimize the likelihood of overestimating the benefits of second-line treatment. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Schering-Plough Schering-Plough

Football players’ contrast sensitivity comparison when wearing amber sport-tinted or clear contact lenses

Background Many experiments are conducted each year in the sporting world to try and improve the existing technology and equipment in an effort to positively influence athletic outcomes. These studies, at times, are concerned about vision and how athletes can improve their visual inputs to respond most advantageously. Sports vision aids are becoming a more integral part of an athlete’s equipment. Recently, sport-tinted contact lenses have become available to athletes of various sports. The purpose of this study was to compare football players’ contrast sensitivity when wearing specially designed sport-tinted contact lenses to that when wearing clear contact lenses or no contact lenses in the case of an emmetropic athlete. Methods Participants were fitted with either clear contact lenses or sport-tinted contact lenses. Spherical equivalent refractions were used because sport-tinted contact lenses are not currently available for astigmatic prescriptions. Contrast sensitivity was measured monocularly on a sine-wave grating chart of 4 spatial frequencies, each with decreasing contrast. Testing then was repeated with the other contact lens. Comparison was made to determine if statistically or clinically significant data would support the claim of increased contrast enhancement for the athletes while wearing the sport-tinted contact lenses. Results Thirty-five subjects participated (35 left eyes), ranging in age from 18 to 32 years. All subjects were professional or collegiate football players. Testing done at 3, 6, 12, and 18 cycles per degree (cpd) of spatial frequency found statistically significant improvement with the sport-tinted contact lenses where P < 0.05. With an examination of the emmetropic-only subgroup, these same results were confirmed at 3 and 6 cpd. Although most of the results were statistically significant, it is questionable whether there is any clinically significant improvement in contrast enhancement while wearing these lenses. Conclusion Sport-tinted contact lenses appear to have a statistically significant effect on contrast sensitivity when worn by a relatively low astigmatic or spherically refracted patient. These results also hold true for enhancing sensitivity in the emmetropic athlete. This information is dampened, however, when considering clinical significance. Overall, there does not appear to be overwhelming evidence that the sport-tinted lenses provide any clinically significant difference when considering contrast enhancement. There are always exceptions to any study; therefore, each case would have to be evaluated by the individual practitioner and the athlete.

Integrated head-thoracic vascular MRI at 3 T: Assessment of cranial, cervical and thoracic involvement of giant cell arteritis

Recently, high-resolution contrast-enhanced MRI has proven to be feasible for noninvasive diagnosis of giant cell arteritis in the cranium. In such examinations, thickening of the vessel wall and/or increased contrast enhancement demonstrate mural inflammation. Typically, the superficial cranial arteries with predominance of the superficial temporal artery are affected by the disease. However, giant cell arteritis can also involve other parts of the vascular system and an examination with extended coverage, including head, neck, and thorax would be advantageous. In this study, a novel approach for integrated head-thoracic vascular MRI at 3 T is presented. Combining first-pass imaging of a single-dose contrast agent with post-contrast imaging permits the assessment of both thoracic aortic geometry and wall, in addition to high-resolution head imaging needed for the analysis of the small superficial cranial arteries. Results from a patient feasibility study are presented and confirm that the protocol can successfully be completed in less than 40 min.

The Role of Heparanase in Lymph Node Metastatic Dissemination: Dynamic Contrast-Enhanced MRI of Eb Lymphoma in Mice

Heparanase expression has been linked to increased tumor invasion, metastasis, angiogenesis and with poor prognosis. The aim of the study was to monitor the effect of heparanase expression on lymph node metastasis, in heparanase-overexpressing subcutaneous Eb mouse T-lymphoma tumors, their draining lymph node. Dynamic contrast-enhanced magnetic resonance imaging (MRI) using biotin-BSAGdDTPA-FAM/ROX was applied for analysis of blood volume, vascular permeability, interstitial convection, for detection of very early stages of such metastatic dissemination. Eb tumors increased extravasation, interstitial convection, lymphatic drain of the contrast material. Interstitial flow directions were mapped by showing radial outflow interrupted in some tumors by directional flow toward the popliteal lymph node. Heparanase expression significantly increased contrast enhancement of the popliteal lymph node but not of the primary tumor. Changes in MR contrast enhancement preceded the formation of pathologically detectable metastases, were detectable when only a few enhanced green fluorescent protein (EGFP)expressing Eb cells were found near and within the nodes. These results demonstrate very early, heparanase-dependent vascular changes in lymph nodes that were visible by MRI following administration of biotin-BSA-GdDTPA-FAWROX, can be used for studying the initial stages of lymph node infiltration.

Multi-detector row CT evaluation of living renal donors prior to laparoscopic nephrectomy.

Since its introduction in 1995, laparoscopic nephrectomy has become the preferred technique at many medical centers for the harvesting of kidneys from living donors for transplantation. Because the field of view at laparoscopic surgery is limited, preoperative radiologic evaluation of the donor's anatomy---the renal veins and arteries, collecting system, and parenchyma--is critical. Spiral computed tomographic (CT) angiography is a fast, safe, minimally invasive, and generally accepted method for preoperative evaluation of the renal vessels. Multi-detector row CT scanners offer shorter image acquisition time, narrower collimation, better spatial resolution, and less tube heating than do single-detector row CT scanners. Multi-row scanners also provide more complete anatomic coverage, increased contrast enhancement of the arteries, and greater longitudinal spatial resolution--all of which are important both for accurate imaging of the renal vasculature and for three-dimensional postprocessing of image data. Dual-phase multi-detector row CT angiography combined with three-dimensional postprocessing enables minimally invasive and highly accurate depiction of the preoperative donor anatomy. To make the most effective use of this method, radiologists must be familiar with its technical aspects, advantages, and potential pitfalls. They also must be able to identify variations in vasculature and in renal and extrarenal anatomy that are important for laparoscopic donor nephrectomy.

Gamma knife radiosurgery for pilocytic astrocytomas

Object. The authors report on the follow-up studies in patients treated at the Karolinska Hospital to evaluate the efficacy of gamma knife radiosurgery (GKS) for pilocytic astrocytoma. Methods. Twelve male and seven female patients were treated (mean age 10.6 years [range 2–60 years]). Sixteen of these patients were children in whom GKS was performed to treat residual tumor after surgery. Most tumors were treated with a prescription dose of 10 to 12 Gy (range 9–20 Gy). The corresponding maximum dose varied between 22 and 30 Gy (range 10–50 Gy). The median clinical follow-up time was 7 years and mean clinical follow-up time 8.5 years. Median radiological follow-up time was 4.7 years and the mean radiological follow-up time was 5.9 years. Tumor control was achieved in all patients. In 85% of the cases a moderate tumor volume reduction was observed after GKS. This result occurred despite the low prescription dose administered. The radiological follow-up studies showed adverse radiation effects in 25% of patients with increasing contrast enhancement and some edema. These effects generally appeared within 7 months and resolved later. Cyst development occurred in two patients, which may have been treatment related. Conclusions. It appears that small pilocytic astrocytomas may be treated with low-prescription-dose GKS, resulting in satisfactory clinical outcomes and only minor side effects. There were a certain number of radiologically demonstrated side effects that appeared relatively early but subsequently resolved. This study should be regarded as a preliminary one because the number of patients is small and the follow-up period is short compared with the natural time course of the disease.

CT of angioedema of the small bowel.

The purpose of this study was to determine the added diagnostic value of CT for the diagnosis of visceral angioedema. Thickening of the small-bowel wall and mucosa with increased contrast enhancement, depiction of more layers of the small-bowel wall than normal, prominent mesenteric vessels, ascites, and fluid accumulation in the small bowel or together in the small bowel and the colon were the most significant CT findings in three patients with visceral angioedema. Findings appear to be transient.

Perfusion magnetic resonance imaging of the lung: characterization of pneumonia and chronic obstructive pulmonary disease. A feasibility study.

Perfusion magnetic resonance (MR) imaging is a promising new method for detection of perfusion defects in the diagnosis of pulmonary embolism. In the present study we evaluated the first-pass characteristics of perfusion MR imaging in patients with pneumonia or chronic obstructive pulmonary disease (COPD), frequent differential diagnoses to pulmonary embolism. Dynamic contrast-enhanced MR images of 12 patients with acute pneumonia and 13 patients with exacerbation of COPD were acquired in both the coronal and transaxial planes (an inversion recovery prepared gradient-echo sequence using 0.05 mmol/kg gadodiamide/injection). The MR images and the signal intensity (SI) versus time curves were characterized for each disease entity and compared with normal lung and the findings in pulmonary embolism from our previous study. The perfusion MR images of pneumonia showed distinct regions of increased contrast enhancement; in COPD with signs of emphysema (11 of the 13 COPD patients), the images showed a coarse pattern of reduced contrast enhancement. The SI versus time curves of pneumonia, COPD with signs of emphysema, and normal lung were statistically different, the respective pooled SI values (+/-95% CI) being as follows: mean baseline SI, 20.7 (1.1), 7.4 (0.4), and 8.5 (0.3); mean peak SI, no peak, 12.9 (1.5), and 27 (4.6); and mean max change of SI in percent, 110 (27), 79 (22), and 205 (52). Perfusion MR imaging of pneumonia and COPD with signs of emphysema showed first-pass that were characteristics promising for diagnostic use. Both the MR images and the SI versus time curves were different from the perfusion characteristics in normal lung and pulmonary embolism shown previously.

DYNAMIC MR IMAGING OF MANDIBULAR STEORADIONECROSIS

Osteoradionecrotic bone has been characterised as hypovascular and metabolically inactive tissue with impaired perfusion. The present study was conducted to determine if dynamic contrast-enhanced MR imaging could provide additional information about the vascularity of radionecrotic mandibular bone. Dynamic contrast-enhanced MR imaging was performed on 10 patients with mandibular osteoradionecrosis (ORN), and on 6 patients, irradiated for oropharyngeal tumours, without symptoms or signs of ORN. Nine patients in the ORN group received a series of 20 hyperbaric oxygen (HBO) treatments, after which the dynamic MR investigation was repeated. Radiation per se did not lead to increased contrast enhancement, whereas all patients with ORN showed marked contrast enhancement of the osteoradionecrotic bone marrow. After HBO treatment, pathological contrast enhancement of the abnormal bone marrow could still be seen, but the rate of enhancement was less than before in 7 of 9 patients. Two patients had an increase in the enhancement rate. The findings suggest the existence of an increased and patent microvasculature.

Dynamic MR imaging of mandibular osteoradionecrosis

Purpose: Osteoradionecrotic bone has been characterised as hypovascular and metabolically inactive tissue with impaired perfusion. The present study was conducted to determine if dynamic contrast-enhanced MR imaging could provide additional information about the vascularity of radionecrotic mandibular bone. Material and Methods: Dynamic contrast-enhanced MR imaging was performed on 10 patients with mandibular osteoradionecrosis (ORN), and on 6 patients, irradiated for oropharyngeal tumours, without symptoms or signs of ORN. Nine patients in the ORN group received a series of 20 hyperbaric oxygen (HBO) treatments, after which the dynamic MR investigation was repeated. Results and Conclusion: Radiation per se did not lead to increased contrast enhancement, whereas all patients with ORN showed marked contrast enhancement of the osteoradionecrotic bone marrow. After HBO treatment, pathological contrast enhancement of the abnormal bone marrow could still be seen, but the rate of enhancement was less than before in 7 of 9 patients. Two patients had an increase in the enhancement rate. The findings suggest the existence of an increased and patent microvasculature.

Optimal protocol for injection of contrast material at MR angiography: study of healthy volunteers.

Forty healthy volunteers, matched for age and body weight, underwent abdominal magnetic resonance angiography with gadopentetate dimeglumine administered by using a power injector. Injection rates were 0.3, 1.0, 2.0, or 3.0 mL/sec. Contrast material doses were 0.1 (single dose) or 0.2 (double dose) mmol/kg. Increased contrast enhancement in the aorta and minimum arteriovenous overlap can be achieved with high flow rate and double-dose injection.

Oblique angle bone SPECT imaging of the lumbar spine, pelvis, and hips. An anatomic study.

Bone SPECT offers advantages over planar imaging in detecting skeletal lesions because of increased contrast enhancement and tomographic effect with the latter, allowing for precise anatomic localization of an uncovered abnormality. However, tomographic sections of curved structures or regions obliquely oriented to the reconstruction plane may have inherent limitations as far as case of image interpretation, which can be overcome by oblique reorientation of the SPECT views. A method for oblique angle presentation of the lumbar spine, pelvis, and hips has been developed with results correlated with radiographic tomograms of a phantom to order to ensure correct anatomic orientation. These oblique SPECT images allow for easier differentiation between facet and pars interarticularis abnormalities, as well as improved imaging of hips and sacrum.

Enhanced MR imaging of the liver after ethanol treatment of hepatocellular carcinoma: evaluation of areas of hyperperfusion adjacent to the tumor.

In the arterial phase of dynamic contrast-enhanced MR images, we observed areas of increased contrast enhancement adjacent to hepatocellular carcinomas treated by percutaneous ethanol injection. The purpose of this study was to assess the frequency, appearance, and location of this hyperperfusion abnormality. It is important not to mistake this finding for other pathologic conditions. Multisection dynamic MR images obtained in 33 consecutive patients with hepatocellular carcinoma treated with percutaneous ethanol injection were reviewed. Hepatic parenchymal hyperperfusion abnormalities were diagnosed when areas of early enhancement were seen in the hepatic parenchyma adjacent to the treated tumor. The location, appearance, and frequency of the findings were recorded. Hepatic parenchymal hyperperfusion abnormalities were observed in 15 (45%) of the 33 patients on arterial-dominant-phase images. Of these 15 patients, 10 (67%) had MR imaging within 1 month after percutaneous ethanol injection. Hyperperfusion abnormalities were located in liver parenchyma adjacent to the lesion with wedge-shaped appearances. In two patients, early opacification of the peripheral portal branch was seen within the area of hyperperfusion abnormalities. Hepatic hyperperfusion abnormalities are commonly seen adjacent to a treated hepatocellular carcinoma on contrast-enhanced MR images. Awareness of this hyperperfusion abnormality, which is caused by increased blood flow after percutaneous ethanol injection, is important because such a finding may be misinterpreted as another pathologic condition such as tumor progression or tumor thrombosis of the portal vein branches.

A 3D T1-weighted gradient-echo sequence for routine use in 3D radiosurgical treatment planning of brain metastases: first clinical results

The authors report on a 3D sequence for MRI of the brain and its application in radiosurgical treatment planning of 35 brain metastases. The measuring sequence, called magnetization — prepared rapid gradient echo (MPRAGE), was compared with 2D T1-weighted spin-echo (SE) sequences following intravenous contrast-medium application in 19 patients with brain metastases. The average diameter of all lesions was similar in both sequences, with 16.8 and 17.0 mm for SE and MPRAGE, respectively. Target point definition was equal in 29 metastases, and in 6 cases superior on MPRAGE, due to better gray-white matter contrast and increased contrast enhancement. In cases of bleeding metastases there was improved depiction of internal structures in 3D MRI. Postprocessing of 3D MPRAGE data created multi-planar reconstruction along any chosen plane with isotropic spatial resolution, which helped to improve radiosurgical isodose distribution in 4 cases when compared to 2D SE. However, sensitivity of 3D MPRAGE to detect small lesions (< 3 mm) was decreased in one patient with more than 50 metastases. We conclude that 3D gradient-echo (GE) imaging might be of great value for radiosurgical treatment planning, but does not replace 2D SE with its current parameters.

Diffuse small-bowel ischemia in hypotensive adults after blunt trauma (shock bowel): CT findings and clinical significance.

The purpose of this study is to describe CT findings of shock bowel (diffuse abnormality of the small bowel observed in hypotensive or hypoperfused patients after blunt abdominal trauma) and to determine the clinical significance of CT-diagnosed shock bowel. A data base search of a radiology data registry indicated 13 patients had CT scans obtained at admission that showed diffuse abnormalities of the small bowel and a corresponding medical history of profound clinical shock preceding CT study. All patients sustained blunt abdominal trauma: nine were involved in motor vehicle collisions, three were struck by motor vehicles, and one had a crushing injury. Vehicular impacts were typically high speed, inducing multisystem injury. Admission and follow-up CT studies were reviewed to characterize and assess the evolution of the abdominal CT findings that occur with shock bowel. Medical records were reviewed to determine blood pressure at the accident scene or on admission, surgical findings, and patient outcome. All patients were severely hypotensive in the field or on admission; three were in cardiac arrest at the scene of the accident. CT scans showed diffuse thickening of the small-bowel wall in all patients, ranging from 7 mm to 15 mm (mean, 11 mm); fluid-filled, dilated small bowel in nine patients; subjectively increased contrast enhancement of the small-bowel wall in six patients; and a flattened inferior vena cava (< 9 mm anteroposterior diameter at renal veins) in 10 patients. The colon appeared normal in all cases. Celiotomy in eight patients revealed normal-appearing small bowel by inspection in two and localized bowel injuries, with the remaining bowel appearing normal in six. Three patients, including one who had celiotomy, had normal-appearing small bowel on repeat CT scans obtained within 5 days of admission, and three had no clinical evidence of small-bowel disease. Three patients died of causes unrelated to bowel pathology. In trauma patients with hypotension, early abdominal CT may show diffuse abnormalities of the small bowel due to prolonged hypoperfusion--shock bowel--with a normal appearing colon. In this study, the CT findings of shock bowel were reversible and were not associated with clinical symptoms.

Differentiation of alveolitis and pulmonary fibrosis with a macromolecular MR imaging contrast agent.

The ability of macromolecular contrast agent (polylysine-[gadopentetate dimeglumine]) to allow differentiation of pulmonary fibrosis and alveolitis at magnetic resonance imaging was investigated. Lung damage was induced by means of left bronchial instillation of 200 micrograms of cadmium chloride. Rats were imaged 3 hours (early alveolitic stage, n = 5), 24 hours (late alveolitic stage, n = 5), and 8 days (fibrotic stage, n = 5) later. Rats imaged 3 hours after cadmium chloride instillation demonstrated a gradually increasing contrast enhancement over 45 minutes (from 314% +/- 110 to 476% +/- 69 over baseline [P less than .01]), indicating a leak of paramagnetic macromolecules from the intravascular into the extravascular spaces. Conversely, lung enhancement remained virtually constant after injection of contrast material in contralateral control lungs and in damaged lungs imaged 24 hours and 8 days after cadmium chloride instillation. Furthermore, the enhancement in the fibrotic lung was lower (170% +/- 50) than that in the alveolitic and control lungs (320% +/- 65 and 298% +/- 61, respectively), indicating a decrease in plasma volume in the fibrotic lung. A macromolecular contrast agent can facilitate the differentiation between the exudative and fibrotic phases of interstitial lung disease.

CT depiction of prostatic zonal anatomy.

The objective of this study was to investigate the frequency of recognition of prostatic zonal anatomy on CT. Computed tomography in 71 patients without known prostate disease was reviewed. Differential attenuation allowed for distinction of the peripheral zone and central gland of the prostate in 24% patients. The peripheral zone was of lower attenuation than the central gland, attributable to relatively increased water content in the peripheral zone. Patients in whom zonal anatomy was evident were significantly older and had prostate glands significantly larger than those in whom the prostate appeared as a homogeneous structure. All patients in whom prostatic zonal anatomy was visualized had received intravenous contrast material injection. Development of benign prostatic hyperplasia nodules within the central gland may contribute to relative increased attenuation or increased contrast enhancement within this region of the prostate gland.

Bowel disease: Prospective comparison of CT and 1.5‐T pre‐ and postcontrast MR imaging with T1‐weighted fat‐suppressed and breath‐hold FLASH sequences

The potential of new high-field-strength magnetic resonance (MR) imaging sequences to evaluate bowel disease was investigated and compared with computed tomographic (CT) studies. Thirty-two patients were studied, 14 with known or suspected gastrointestinal tumors and 18 with known or suspected bowel inflammatory conditions. T1-weighted fat-suppressed spin-echo and breath-hold FLASH (fast low-angle shot) images were obtained before and after intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine. Pathologic confirmation was obtained by biopsy (n = 18), surgical excision (n = 8), or endoscopy (n = 6). CT and MR images were analyzed separately in a prospective fashion and reviewed by consensus. Information from CT and MR images was comparable in cases of confirmed bowel neoplasia. CT scans had better spatial resolution, while fat-suppressed gadolinium-enhanced MR images had better contrast resolution. In the 18 cases of bowel inflammation, CT scans showed concentric wall thickening in 16, while MR images showed concentric wall thickening in 14 and increased contrast enhancement in 17. Contrast enhancement was better appreciated on fat-suppressed images than on FLASH images. The results suggest that MR imaging may play a role in the evaluation of bowel disease.

Use of black diamond-like carbon films as a contrast enhancement layer for liquid-crystal displays

We report development of single-layer, highly durable, pinhole-free, abrasion-resistant, chemically inert ‘‘black coating’’ suitable for use as a contrast enhancement layer for liquid- crystal display devices. The single layer is a diamond-like carbon coating that has a high extinction coefficient and appears black due to optical absorption. The optical transmittance is less than 2% over the visible spectrum, and the reflectance is about 20%. Furthermore, this coating is easy to deposit onto large-area substrates at high deposition rates. The coating is sufficiently durable, electrically insulating, and chemically compatible with liquid-crystal display materials. Its hardness exceeds that of SiC (9+ on Mohs scale), and it is resistant to abrasion and most common solvents and acids. It exhibits good adhesion to glass, silicon, metal, and oxide substrates. Films of this material have been used to provide an increased contrast enhancement ratio in liquid-crystal displays. Details on the synthesis of these films are presented. Also, data on the optical and mechanical properties of these films as well as their use as contrast enhancement layers for liquid-crystal displays are presented.

Computed Tomography of the Urinary Bladder Shortly after Radiation Therapy for Rectal Carcinoma

Eighteen patients with rectal carcinoma were examined with computed tomography (CT), before and shortly after preoperative irradiation. Changes in the bladder that could be mistaken for tumor growth did not occur at CT. However, considerable individual variations were seen. Radiation therapy did not result in increased contrast enhancement of the bladder wall after irradiation. The bladder wall thickness increased somewhat during and after treatment and the bladder volume was reduced. Localized thickening with little contrast enhancement was seen in the anterior bladder wall in 3 patients. One case of irradiation cystitis was noted. Edema was seen in the perivesical fat, but could in no case be mistaken for tumor growth.