Hepatic peroxisome proliferator-activated receptor α may have an important role in the toxic effects of di(2-ethylhexyl)phthalate on offspring of mice

Maternal exposure to di(2-ethylhexyl)phthalate (DEHP) is associated with adverse effects on offspring, and the metabolites are agonists of peroxisome proliferator-activated receptor (PPAR) α, which exhibits species differences in expression and function. This study aimed to clarify the mechanism of DEHP-induced adverse effects on offspring in relation to maternal mouse and human PPARα. Male and female Sv/129 wild-type (mPPARα), Pparα-null and humanized PPARα (hPPARα) mice were treated with diets containing 0%, 0.01%, 0.05% (medium) or 0.1% (high) DEHP. After 4 weeks, males and females were mated. Dams were killed on gestational day 18 and postnatal day (PND) 2. High-dose DEHP decreased the number of total and live fetuses, and increased resorptions in mPPARα mice. In hPPARα mice, resorptions were increased above the medium dose, and the number of births was decreased at the high dose. The number of live pups on PND2 was decreased over the medium dose in mPPARα and at the high dose in hPPARα mice. No such findings were observed in Pparα-null mice. High-dose DEHP decreased plasma triglyceride in pregnant mPPARα mice, but not in Pparα-null and hPPARα ones. Above the medium dose in mPPARα mice significantly reduced hepatic microsomal triglyceride transfer protein (MTP) expression. Medium- and/or high-dose DEHP increased the levels of maternal PPARα target genes in mPPARα and hPPARα mice. Taken together, PPARα expression is required for the toxicity of DEHP in fetuses and pups and altered plasma triglyceride levels, through regulation of MTP may be important in mPPARα mice and not in hPPARα mice.

Differential response to trichloroethylene-induced hepatosteatosis in wild-type and PPARalpha-humanized mice

BACKGROUND

Trichloroacetic acid, an oxidative metabolite of trichloroethylene (TRI), is a ligand of the peroxisome proliferator-activated receptor alpha (PPAR) alpha, which is involved in lipid homeostasis and anti-inflammation.

OBJECTIVE

We examined the role of mouse and human PPARalpha in TRI-induced hepatic steatosis and toxicity.

METHODS

Male wild-type (mPPARalpha), Pparalpha-null, and humanized PPARalpha (hPPARalpha) mice on an Sv/129 background were exposed via inhalation to 0, 1,000, and 2,000 ppm TRI for 8 hr/day for 7 days. We assessed TRI-induced steatosis or hepatic damage through biochemical and histopathological measurements.

RESULTS

Plasma alanine aminotransferase and aspartate aminotransferase activities increased in all mouse lines after exposure to 1,000 and 2,000 ppm TRI. Exposure induced hepatocyte necrosis and inflammatory cells in all mouse lines, but hepatic lipid accumulation was observed only in Pparalpha-null and hPPARalpha mice. No differences were observed in TRI-mediated induction of hepatic PPARalpha target genes except for a few genes that differed between mPPARalpha and hPPARalpha mice. However, TRI significantly increased expression of triglyceride (TG)-synthesizing enzymes, diacyl-glicerol acyltransferases, and PPARgamma in Pparalpha-null and hPPARalpha mice, which may account for the increased TG in their livers. TRI exposure elevated nuclear factor-kappa B (NFkappaB) p52 mRNA and protein in all mice regardless of PPARalpha genotype.

CONCLUSIONS

NFkappaB-p52 is a candidate molecular marker for inflammation caused by TRI, and PPARalpha may be involved in TRI-induced hepatosteatosis. However, human PPARalpha may afford only weak protection against TRI-mediated effects compared with mouse PPARalpha.

High susceptibility to severe infectious complications at reinduction chemotherapy in patients who relapse after stem cell transplantation

Patients who relapse after stem cell transplantation (SCT) usually appear to be liable to severe infectious complications at reinduction chemotherapy compared to patients at the first induction therapy, though this is not statistically substantiated. The aim of this study was to analyze episodes of infectious complications during reinduction chemotherapy among patients who relapsed after SCT compared with those at the first induction chemotherapy. Between February 1988 and March 2004, 145 children received SCT, and 17 (12 with hematologic malignancies and 5 with solid tumors) were enrolled as eligible subjects for this study. Positive blood cultures (sepsis) were present in six patients exclusively at the reinduction therapy but none at the first induction (P = .009). Three of the six patients progressed to septic shock. Moreover, all patients positive for blood cultures were those with hematologic malignancy (P = .007), and every patient with septic shock had received allogenic transplantation. Our results showed that reinduction chemotherapy needs attention for severe infectious complications, particularly among patients with hematologic malignancies receiving allogenic transplantations. Possible immaturity of the reconstructed systemic immune system and/or insufficient recovery of mucosal protective functions in the patients after SCT are discussed in view of their high susceptibility to severe infectious complications.

Bisphenol A may cause testosterone reduction by adversely affecting both testis and pituitary systems similar to estradiol

Bisphenol A (BPA) causes reproductive toxicities, but the mechanisms are still unclear. In the present study, we sought to clarify these mechanisms in comparison with those of 17beta-estradiol (E2). Prepubertal Wistar/ST male rats (4 weeks old) were subcutaneously administered BPA (0, 20, 100 and 200 mg/kg/day) or E2 (10 and 100 microg/kg/day) for 6 weeks. Both BPA and E2 treatments decreased plasma and testicular testosterone levels, and plasma luteinizing hormone (LH), but not E2 and follicle-stimulating hormone levels, though E2 treatment increased its plasma level. In relation to the decreased testosterone levels, BPA and E2 decreased expressions of steroidogenic enzymes and cholesterol carrier protein in Leydig cells. Thus, decreased testosterone levels in plasma might have resulted from decreased expressions of these enzymes and protein as well as from decreased plasma LH levels. Interestingly, the changes in steroidogenic enzymes and carrier protein were observed at lower levels of exposure to BPA or E2 than those inhibiting plasma LH levels. Microscopically, 200 mg/kg BPA and 100 microg/kg E2 significantly decreased Leydig cell numbers in the testis. In addition, BPA and E2 also decreased expression of estrogen receptor alpha-mRNA, which might be related to the decreased numbers of Leydig cells. Thus, BPA directly affects not only the Leydig cells but also the pituitary gland, but the former may be impaired at lower exposure concentrations than the latter.

Microgram-order ammonium perfluorooctanoate may activate mouse peroxisome proliferator-activated receptor alpha, but not human PPARalpha

Perfluorooctanoic acid (PFOA) is a ligand for peroxisome proliferator-activated receptor (PPAR) alpha, which exhibits marked species differences in expression and function, especially between rodents and humans. We investigated the functional difference in PFOA response between mice and humans, using a humanized PPARalpha transgenic mouse line. Three genotyped mice, 129/Sv wild-type (mPPARalpha), Pparalpha-null mice and humanized PPARalpha (hPPARalpha) mice (8-week-old males) were divided into three groups: the first was treated with water daily for 2 weeks by gavage (control group), and the remaining two groups were treated with 0.1 and 0.3mg/kg ammonium perflurooctanate (APFO), respectively, for 2 weeks by gavage. The APFO dosages used did not influence the plasma triglyceride or total cholesterol levels in any mouse line, but the high dose increased both hepatic lipid levels only in mPPARalpha mice. APFO increased mRNA and/or protein levels of PPARalpha target genes cytochrome P450 Cyp4a10, peroxisomal thiolase and bifunctional protein only in the liver of mPPARalpha mice, but not in Pparalpha-null or hPPARalpha mice. This chemical also increased expression of mitochondrial very long chain acyl-CoA dehydrogenase only in the liver of mPPARalpha mice. Taken together, human PPARalpha may be less responsive to PFOA than that of mice when a relatively low dose is applied. This information may be very valuable in considering whether PFOA influences the lipid metabolism in humans.

"Hypothesis of seven balances": molecular mechanisms behind alcoholic liver diseases and association with PPARalpha

OBJECTIVES

The purpose of this review to collate current leading scientific advances of molecular mechanisms in alcoholic liver diseases and to propose a working "hypothesis of seven balances" in relation to peroxisome proliferator activated receptor alpha (PPARalpha), which has important roles in fatty acid oxidation, oxidative stress, inflammatory responses, and possibly liver fibrosis.

METHODS

We conducted an extensive literature review of over a hundred publications and collated the findings with evidence generated in our laboratory.

RESULTS

Our research points to a working hypothesis of seven balances for alcoholic liver diseases consisting of: 1) ethanol oxidation balance in hepatocytes; 2) PPAR alpha activities in liver; 3) fatty acid metabolism balance in hepatic mitochondria; 4) gastrointestinal response to ethanol, acetaldehyde and lipopolysaccharide (LPS); 5) Kupffer cells response to LPS, oxidative stress and inflammatory cytokines; 6) adiponectin levels in plasma interchangeably regulated by tumor necrosis factor-alpha (TNF-alpha); and 7) stellate cells response to all of the above promoting hepatic fibrosis. Cellular mechanisms behind alcoholic liver diseases reveal close temporal associations of PPARalpha, adiponectin, TNF-alpha, cellular inflammation, proliferation, and potentially fibrosis as illustrated in "the hypothesis of seven balances."

CONCLUSIONS

The regulation and adjustment of PPARalpha activation underlying the balance of molecular cascades might resolve the progression of alcoholic liver diseases by reducing oxidative stress and inflammatory effects induced by nuclear factor-kappaB as well as the associated adiponectin pathway. Further elucidation of these pathways would reveal exciting new prospects for treating alcoholic liver diseases and other related liver disorders.

Different adaptations of alpha-actinin isoforms to exercise training in rat skeletal muscles

AIM

Alpha (alpha)-actinins are located in the skeletal muscle Z-line and form actin-actin cross-links. Mammalian skeletal muscle has two isoforms: alpha-actinin-2 and alpha-actinin-3. However, the response of alpha-actinin to exercise training is little understood. Therefore, the current study examined the effects of exercise training on the expression level of two alpha-actinin isoforms in skeletal muscles.

METHODS

Twelve male Wistar rats were assigned randomly to a control (C; n = 6) or exercise training (T; n = 6) group. After T animals were trained on an animal treadmill for 9 weeks, alpha-actinin-2 and alpha-actinin-3 levels in the plantaris, white and red gastrocnemius muscles were analysed. In addition, changes in the myosin heavy chain (MyHC) composition were assessed, and muscle bioenergetic enzyme activities were measured.

RESULTS

Results show that exercise training increased alpha-actinin-2 expression levels in all muscles (P < 0.05). However, no significant difference was found in alpha-actinin-3 expression levels between C and T animals. Subsequent MyHC analyses of all muscle showed an MyHC shift with direction from IIb to IIa. Furthermore, enzymatic analysis revealed that exercise training improved enzyme activities related to aerobic metabolism.

CONCLUSION

The results of this study demonstrate that exercise training alters the expression level of alpha-actinin at the isoform level. Moreover, the increase in expression levels of alpha-actinin-2 is apparently related to alteration of skeletal muscle: its aerobic capacity is improved.

Phase II trial of adjuvant hyperthermic intraperitoneal chemotherapy with three drugs for the prophylactic treatment of carcinomatosis after resection of advanced gastric cancer

e15588

Background: This prospective study was performed to assess the efficacy and safety of hyperthermic intraperitoneal chemotherapy (HIPEC) with three drugs in patients with curative resection of T3 or T4 advanced gastric cancer. Methods: Patients with curative resection of clinically T3 or T4 advanced gastric cancer were required to be under 75 years of age and to have adequate organ function. After the curative resection of gastric cancer with D2 lymph node dissection and the reconstruction of the alimentary tract, HIPEC was carried out for 30 minutes with 50mg of CDDP, 10mg of MMC, and 1000mg of 5-FU in 5 L saline maintained at 42–43°C. Patients were given an adjuvant S-1 treatment after surgery. Primary endpoint of this study was overall survival. Results: A total of 29 patients were eligible. Pathologically, 8 patients had sub-serosal invasion (pT2(ss)), 18 patients had serosal invasion (pT3), and 3 patients had adjacent organ invasion (pT4). These patients included pT2(ss)pN0 (n=2), pT2(ss)pN1 (n=6), pT3pN0 (n=4), pT3pN1 (n=9), pT3pN2 (n=5), pT4pN0 (n=1), and pT4pN1 (n=2). Median follow-up period was 44 months (10–72 months). Overall 5- year survival rate in all eligible patients was 89.5%. Overall 5-year survival rate in patients with pT2(ss), pT3, or pT4 was 100%, 82.4%, or 100%, respectively. Three patients with pT3 had recurrence of pleural dissemination (n=1), lymph node metastases (n=1), or pulmonary metastases and peritoneal dissemination (n=1). A total of 7 patients had postoperative complications such as continuous pancreatic juice secretion (13.8%), abdominal abscess (10.3%), leakage of the anastomosis (3.4%), and pulmonary insufficiency (10.3%). Conclusions: The present study suggests that HIPEC with three drugs after curative resection of advanced gastric primary cancer is associated with improved overall survival with an acceptable morbidity.

No significant financial relationships to disclose.

Regenerating gene 1α (REG 1α) expression and new treatment strategies in early non-small cell lung cancer

e22178

Background: Regenerating gene (REG) I was originally isolated as an endogenous growth factor from pancreatic islet β cells. REG Iα protein is suggested to be involved in carcinogenesis in various gastroenterologic tissues. In the present study, to elucidate roles for REG Iα in non-small cell lung cancer (NSCLC), we investigated REG Iα expression in NSCLCs, focusing especially on its relationship with prognosis. Methods: We enrolled 70 NSCLCs (adenocarcinoma (AC)(n=48) and squamous cell carcinoma (SCC)(n=22)) who received surgery at Nara Medical University Hospital. Total RNA was extracted from each tumor tissue and corresponding normal lung tissue (NL)(n=70), cDNA was then reverse-transcribed from total RNA, and quantitative real-time reverse transcriptase-polymerase chain reaction was then carried out. The expression level of REG Iα in each sample was normalized with respect to that of β-actin, and the cutoff level was set at average+3SD expression of the 70 NLs. We also examined the relationship between REG 1α expression in the tumor tissue and the prognosis. Results: Six (12.5%) of the 48 ACs and 5 (22.7%) of the 22 SCCs were positive for REG Iα gene, and which is higher than that of NLs (2 of 70: 2.9%). After median follow-up of 26.2 months, 12 patients died due to disease progression. The survival rate among the REG 1α positive patients was significantly worse than among the REG 1α negative patients in ACs (P<0.05), and not significantly but worse in SCCs (P=0.07). In case of stage I, none of REG 1α negative patient died in both ACs and SCCs compared with 4 patients died of positive patients (AC:2, SCC:2), and also the survival rate among the REG 1α positive patients was significantly worse than among the negative patients in ACs (P<0.01) and SCCs (P<0.05). Disease free survival of REG 1α positive patients was also worse than negative patients in ACs (P<0.05) and SCCs (P=0.16). Conclusions: REG Iα expression in NSCLCs may be the risk factor for poor prognosis, and we anticipate that it will enable us to provide more appropriate and individualized treatment to patients of early NSCLC.

No significant financial relationships to disclose.

Identification of the distal dural ring with use of fusion images with 3D-MR cisternography and MR angiography: application to paraclinoid aneurysms

BACKGROUND AND PURPOSE

The distal dural ring (DDR) represents the anatomic border between the extradural and intradural internal carotid arteries (ICAs). The purpose of this study was to examine whether 3D-MR cisternography and MR angiography (MRA) fusion images can identify the boundary between the CSF and the cavernous sinus, which might represent the DDR.

MATERIALS AND METHODS

Thirty-six consecutive patients with 39 ICA aneurysms were examined with use of MR fusion images with 3D-cisternography and MRA on a 1.5T unit. Two neuroradiologists evaluated the configuration of the carotid cave and the location of the aneurysms on fusion images and classified them as intradural, transdural, and extradural aneurysms.

RESULTS

The borderline between the CSF and the cavernous sinus was visualized on fusion images in all patients. The carotid cave configuration in 72 ICAs was classified as having no dent (n = 31), a shallow dent (n = 27), and a deep dent (n = 14). The MR fusion images led to the classification of 39 ICA aneurysms as 21 intradural, 6 transdural, and 12 extradural. The interobserver agreement of MR fusion images was excellent (kappa = 0.80).

CONCLUSIONS

Fusion images with 3D-cisternography and MRA yielded clear visualization of the boundary between the suprasellar cistern and cavernous sinus indicating the DDR. This imaging technique may provide additional information in consideration of a treatment option for paraclinoid aneurysms.

Subtraction 3D CT angiography with the orbital synchronized helical scan technique for the evaluation of postoperative cerebral aneurysms treated with cobalt-alloy clips

BACKGROUND AND PURPOSE

CT angiography (CTA) has been used for the evaluation of intracranial aneurysms and recently has been applied to assess postoperative aneurysms treated with titanium-alloy clips. We investigated the clinical usefulness of subtraction CTA by using the orbital synchronized helical scan technique (OSHST) for evaluating intracranial aneurysms surgically treated with cobalt-alloy clips.

MATERIALS AND METHODS

We scanned an agar gel phantom with a cobalt-alloy clip mounted in the center by using subtraction CT with and without OSHST. Eighteen patients (20 aneurysms) who underwent surgery with cobalt-alloy clips were postoperatively evaluated with subtraction CTA with OSHST, and the results were compared with those from digital subtraction angiography. Two neuroradiologists independently evaluated the 3D CTA images and source images with and without subtraction for the presence of residual flow in the aneurysm and stenotic change in parent or neighboring arteries.

RESULTS

For the phantom study, significantly fewer artifacts from clips were noted on images obtained by using subtraction CT with OSHST than on those obtained without OSHST. For the clinical study, subtraction CTA with OSHST also showed fewer clip artifacts than did conventional CTA. Image quality was poor, and we were unable to diagnose residual neck for 5% (1/20) with subtraction CTA with OSHST and 75% (15/20) with conventional CTA. For evaluation of adjacent vessels, image quality was poor for none (0/20) with subtraction CTA with OSHST and for 55% (11/20) with conventional CTA. For subtraction CTA with OSHST, sensitivity in detecting residual neck was 1.0, and specificity was 0.94. For conventional CTA, sensitivity and specificity were both 0.25.

CONCLUSIONS

OSHST is a useful technique for subtracting cobalt-alloy clips, and subtraction CTA with OSHST is available for evaluating aneurysms after clipping with cobalt-alloy clips.

[Coronary artery bypass grafting for simultaneous subacute stent thrombosis after sirolimus-eluting stent implantation]

An 82-year-old man developed simultaneous stent thrombosis 11 days after the implantation of a sirolimus-eluting stent (SES) in the proximal left anterior descending artery (LAD) and the proximal right coronary artery (RCA). The patient immediately underwent percutaneous coronary intervention; however, his condition became critical due to the development of recurrent stent thrombosis, and emergent coronary artery bypass grafting with saphenous vein grafts was performed. Postoperative angiography showed good patency of both grafts; thrombus formation in the LAD and RCA was negative. Since the patient had a history of liver dysfunction due to ticlopidine administration, the thienopyridine derivative was not administered; this was believed to be the main cause of subacute stent thrombosis. He was administered aspirin, cilostazol, and sarpogrelate instead. A good postoperative course was achieved only using aspirin. This case demonstrates that simultaneous SES thrombosis in multivessel lesions poses a life-threatening situation.

Acute coronary artery dilation due to Kawasaki disease and subsequent late calcification as detected by electron beam computed tomography

We wanted to clarify the relationships between the degree of acute coronary artery dilation caused by Kawasaki disease and subsequent late calcification. Electron beam computed tomography (EBCT) was used to study 79 patients who had previously undergone selective coronary angiograms less than 100 days after the onset of Kawasaki disease. The EBCT was performed using an Imatron C-150 with a 100-ms exposure time and consecutive images at 6-mm intervals. The interval from the onset of Kawasaki disease to EBCT ranged from 2 to 242 months (median, 103 months). The maximum diameters of the right coronary, the left anterior descending, and the left circumflex arteries, as well as the bifurcation of the left coronary artery were measured in the initial coronary angiograms. A total of 250 branches, including 53 left coronary arteries, were measured, and the relationship between the degree of the initial coronary artery dilation and subsequent calcification in the branches and left coronary artery was analyzed. The coronary arterial diameter of all branches that eventually calcified was 6 mm or greater. The incidence of calcification in branches measuring 6 mm or greater on the initial coronary angiogram was 12% at 5 years, 44% at 10 years, and 94% at 20 years (n = 141). Dilation greater than 6 mm is associated with a high probability of late calcification.

Comparison of Gd-DTPA-induced signal enhancements in rat brain C6 glioma among different pulse sequences in 3-Tesla magnetic resonance imaging

BACKGROUND

T1-shortening contrast media are routinely used in magnetic resonance (MR) examinations for the diagnosis of brain tumors. Although some studies show a benefit of 3 Tesla (T) compared to 1.5T in delineation of brain tumors using contrast media, it is unclear which pulse sequences are optimal.

PURPOSE

To compare gadopentetate dimeglumine (Gd-DTPA)-induced signal enhancements in rat brain C6 glioma in the thalamus region among different pulse sequences in 3T MR imaging.

MATERIAL AND METHODS

Five rats with a surgically implanted C6 glioma in their thalamus were examined. T1-weighted brain images of the five rats were acquired before and after Gd-DTPA administration (0.1 mmol/kg) using three clinically available pulse sequences (spin echo [SE], fast SE [FSE], fast spoiled gradient echo [FSPGR]) at 3T. Signal enhancement in the glioma (E(T)) was calculated as the signal intensity after Gd-DTPA administration scaled by that before administration. Pulse sequences were compared using the Tukey-Kramer test.

RESULTS

E(T) was 1.12+/-0.05 for FSE, 1.26+/-0.11 for FSPGR, and 1.20+/-0.11 for SE. FSPGR showed significantly higher signal enhancement than FSE and comparable enhancement to SE.

CONCLUSION

FSPGR is superior to FSE and comparable to SE in its ability to delineate rat brain C6 glioma in the thalamus region.

Preoperative visualization of the artery of Adamkiewicz by intra-arterial CT angiography

BACKGROUND AND PURPOSE

CT and MR angiographies have been reported to visualize the artery of Adamkiewicz (AKA) noninvasively to prevent spinal cord ischemia in surgery of thoracic descending aortic aneurysms. The purpose of this work was to compare the usefulness of CT angiography (CTA) with intra-arterial contrast injection (IACTA) with that of conventional CTA with intravenous contrast injection (IVCTA).

MATERIALS AND METHODS

We enrolled 32 consecutive patients with thoracic or thoracoabdominal aortic aneurysms who were scheduled for surgical repair or endovascular stent-graft treatment. All of the CTA images were obtained using a 16-detector row CT scanner and 100 mL of contrast material (370 mg/mL) injected at a rate of 5 mL/s. Contrast was injected via the antecubital veins of 15 patients and via a pig-tail catheter placed at the proximal portion of the descending aorta in 17 patients who underwent IVCTA and IACTA, respectively. Two datasets were reconstructed from 2 consecutive scans. The AKA was identified as a characteristic hairpin curved vessel in the anterior midsagittal surface of the spine and by the absence of further enhancement in the second rather than in the first phase. Continuity between the AKA and aorta was confirmed when the vessel could be traced continuously by paging the oblique coronal multiplanar reconstruction or original axial images.

RESULTS

Intra-arterial contrast injection was significantly more sensitive in identifying the AKA than IVCTA: 16 (94.1%) of 17 versus 9 (60.0%) of 15 (P = .033). Continuity between the AKA and aorta through intercostal or lumbar artery was confirmed in 14 (87.5%) of 16 and 5 (55.6%) of 9 of the IACTA and IVCTA groups, respectively.

CONCLUSION

Intra-arterial contrast injection detected the AKA at a high rate and verified continuity from the aorta to the AKA.

[Emergent coronary artery bypass grafting in a survivor of out-of-hospital cardiac arrest]

We report a case of emergent coronary artery bypass grafting (CABG) in a survivor of an out-of-hospital cardiac arrest. A 64-year-old male driver lost consciousness and collapsed in a rice paddy field. A bystander placed him in a car and immediately started cardiopulmonary resuscitation after confirming the presence of pulselessness and apnea. Emergency medical service providers performed a defibrillation of ventricular fibrillation by using an automated external defibrillator (AED), and the patient was transferred to the critical care center in our hospital. Coronary angiography revealed a thrombus in the left main trunk (LMT), total occlusion of the left anterior descending artery (LAD) and the right coronary artery (RCA), and 90% stenosis of the left circumflex artery (Cx). Since the patient recovered consciousness 1 hour after admission and did not undergo any critical trauma, an on-pump CABG was performed for 3 vessels. He was discharged on the postoperative day 23, and he resumed a normal life.

Association between signal hyperintensity on T1-weighted MR imaging of carotid plaques and ipsilateral ischemic events

BACKGROUND AND PURPOSE

To investigate associations between cerebral ischemic events and signal hyperintensity in T1-weighted MR imaging (T1WI) of carotid plaque according to stenosis severity and to estimate persistence of T1WI signal hyperintensity.

METHODS

A total of 222 patients (392 atherosclerotic carotid arteries) underwent plaque imaging using 3D inversion-recovery-based T1WI (magnetization-prepared rapid acquisition with gradient-echo [MPRAGE]). Carotid plaque with intensity on MPRAGE of >200% that of adjacent muscle was categorized as "high signal intensity" and correlated with ipsilateral ischemic events within the previous 6 months. A total of 58 arteries (35 patients) underwent repeat MR imaging a total of 70 times at a median interval of 279 days (range, 10-1037 days).

RESULTS

Ipsilateral ischemic events were more frequent in patients with MPRAGE high signals than in patients with low signals in the 0%-29%, 30%-69%, and 70%-99% stenosis groups: Relative risk (95% confidence interval) was 2.50 (0.96-6.51), 7.55 (1.84-31.04), and 1.98 (1.01-3.90), respectively. In the 70 cases of repeat MR imaging, 29 of 30 cases with high signals on the preceding MR imaging maintained high signals. Of the 58 arteries that underwent repeat MR imaging, 4 of 22 carotid arteries with high signals developed ipsilateral subsequent ischemic events within 1 year, whereas none with low signals developed subsequent events.

CONCLUSIONS

Carotid plaque signal hyperintensity on T1WI is strongly associated with previous ipsilateral ischemic events, persisting over a period of months, and may indicate risk of subsequent events. Larger clinical trials are warranted to clarify associations between signal hyperintensity and risk of subsequent cerebral ischemic events.