Lowering the dose in head CT using adaptive statistical iterative reconstruction

BACKGROUND AND PURPOSE

While CT has found wide use in medical practice, it is also a substantial source of radiation exposure and is associated with an increased lifetime risk of cancer. There is an urgent need for new approaches to reduce the radiation dose in CT. In this regard, ASIR is an alternative method to FBP. We assessed the effect of ASIR on dose reduction in adult head CT.

MATERIALS AND METHODS

We retrospectively evaluated a sample of 149 adult head CT examinations that were divided into 2 groups, STD and LD. We lowered the tube current and used ASIR in the LD group. SNR and CNR were analyzed. Dose parameters were recorded while subjective image noise, sharpness, diagnostic acceptability, and artifacts were graded. The Student t test, the Mann-Whitney U test, and κ statistics were used for statistical analyses.

RESULTS

We achieved a dose reduction of 31% in the LD group (STD, 2.3 ± 0.1 mSv; LD, 1.6 ± 0.1 mSv; P < .001). There was no significant difference in the noise measured in the air between the 2 comparison groups (P = .273). Noise in the CSF was higher in the STD group (P < .001), while the noise in the WM was higher in the LD group (P < .001). Differences in the CNR between groups were insignificant, but the STD group displayed better SNR values. There was no significant difference in the modal scores of diagnostic acceptability (P = .062) and the artifacts (P = .148) between the 2 groups. Better scores for subjective image noise (P < .001) and sharpness (P = .04) were observed in the STD group.

CONCLUSIONS

ASIR appears to be useful in reducing the dose in adult head CT examinations. While the effect of ASIR on noise reduction observed in the present study of head CT is less than that reported previously in abdomen and chest CT, these findings encourage further prospective studies in larger patient samples.

Primitive persistent carotid-basilar and carotid-vertebral anastomoses: a report of seven cases and a review of the literature

The persistence of embryonic carotid-basilar and carotid-vertebral anastomoses was investigated retrospectively in 4,400 cerebral angiograms. Six primitive persistent carotid-basilar anastomoses and one primitive persistent carotid-vertebral anastomosis were found. In 4,400 cerebral angiograms, the incidence of primitive carotid-basilar and carotid-vertebral anastomoses was 0.14% and 0.023% respectively. Primitive persistent anastomoses are associated with intracranial vascular anomalies, especially aneurysms. The clinical and pathological findings in combination with these primitive persistent anastomoses were also examined.

Endovascular Treatment for Near Occlusion of the Internal Carotid Artery : 30-Day Outcome and Long-Term Follow-Up

BACKGROUND

The treatment strategy and the correct incidence of near occlusion (NO) of the internal carotid artery (ICA) is still controversial. In routine radiological imaging NO can easily be misdiagnosed as complete occlusion and there is no consensus on the standard treatment strategy.

PURPOSE

To present our perioperative and long-term follow-up results of ICA NO patients treated with carotid artery stenting (CAS).

MATERIAL AND METHODS

Between 2004-2014 a total of 182 patients with ICA NO were evaluated for CAS. The study included 132 male (72.5 %) and 50 female (27.5 %) patients with a mean age of 70.2 years. Patients underwent a clinical neurological evaluation and radiological imaging of the carotid arteries before the CAS procedure. Of the patients 80 (44 %) were asymptomatic. The median clinical and carotid Doppler ultrasound (DUS) follow-up period was 64 months (range 18-124 months).

RESULTS

In 182 patients CAS were performed, 4 patients (2.2 %) developed minor stroke, 2 patients (1.1 %) developed myocardial infarction but no major stroke or death occurred in the following 30-day period. Asymptomatic restenosis was detected in seven patients (3.8 %) in the follow-up period.

CONCLUSION

With sufficient neurological evaluation during pretreatment and posttreatment periods and when the procedure is performed with technologically developed products by an experienced interventional team, CAS is beneficial in patients with ICA NO.

MR dacryocystography in the evaluation of patients with obstructive epiphora treated by means of interventional radiologic procedures

BACKGROUND AND PURPOSE

Most imaging techniques used for the evaluation of obstructive epiphora, such as DS DCG, rely on undesired ionizing radiation. We evaluated the efficacy of topical contrast-enhanced MR DCG in comparison with DS DCG in patients with obstructive epiphora who underwent balloon DCG or stent placement.

MATERIALS AND METHODS

Thirty-six LDSs of 21 patients treated with balloon DCG (n = 11) or stent placement (n = 11) were examined with MR DCG and DS DCG. Contralateral LDSs (n = 14) were also evaluated in patients with unilateral disease. A sterile 0.9% NaCl solution containing 1:100 diluted gadolinium chelate was instilled into conjunctival sacs. The 3D FSPGR sequence was used with a 1.5T scanner. MR and DS DCG findings were scored and compared according to morphology of the lacrimal sac, junction, and NLD and the presence of contrast media in the nasal cavity.

RESULTS

Comparison of MR DCG and DS DCG findings showed no significant statistical differences in reference to anatomic locations according to the McNemar test (P > .05). Good or very good agreement (κ value > 0.61) was observed according to the κ statistics.

CONCLUSIONS

Topical contrast-enhanced MR DCG is an effective and reliable noninvasive method for evaluation of the LDS in patients treated with IR procedures. This method avoids both cannulation and ionizing radiation and can, therefore, be repeated as often as is necessary in these complex patients.

Long-term results of balloon dacryocystoplasty: success rates according to the site and severity of the obstruction

PURPOSE

To evaluate the long-term patency of lacrimal drainage system (LDS) after balloon dacryocystoplasty (BD) and to give the long-term success rates according to the severity and localization of the obstruction.

METHODS

Between May 1993 and December 2003, BD was attempted in 117 eyes of 108 patients with idiopathic-acquired LDS obstruction. Patients with active dacryocystitis, dacryolithiasis, traumatic obstruction or lacrimal mass, obstructions at the superior or inferior canaliculi lateral to the common canaliculus, and follow-up period less than 36 months were excluded from the study.

RESULTS

The results of BD were evaluated in 99 eyes of 94 cases. The obstruction was seen at the common canaliculus in seven eyes, proximal nasolacrimal duct in 70 eyes, and distal nasolacrimal duct in 22 eyes. The mean follow-up period was 100.0+/-38.4 months (range: 36-142 months). The long-term overall success rate was 40.8% (20/49 eyes) in complete obstruction and 68% (34/50 eyes) in partial obstruction. The clinical success rate was 57.1% in common canalicular (complete: 33.3%, partial: 75%), 50% in proximal nasolacrimal duct (complete: 38.5%, partial: 64.5%), and 68.2% in distal nasolacrimal duct (complete: 57.1%, partial: 73.3%) obstructions. The overall success was 54.5% (54/99 eyes) for the entire series at the last clinical follow-up visit.

CONCLUSION

The long-tem success rate of BD for the treatment of epiphora is low and is not comparable to conventional dacryocystorhinostomy. More predictable results can only be achieved in carefully selected patients and this procedure can be recommended in cases demonstrating partial obstruction of the distal nasolacrimal duct.

Thromboangiitis obliterans (Buerger's disease) in women (a reevaluation)

Thromboangiitis obliterans (TAO) is an occlusive vascular disease traditionally known to be almost exclusive to young male smokers. The disease was considered to be extremely rare in women, seen only as isolated, novel case reports in the literature. In the past decade, however, a dramatic increase in the incidence of female TAO has been observed. In this paper the authors report 7 cases of clinically and angiographically verified female TAO. The world literature in regard to the diagnostic criteria, changing incidence, and etiology is reviewed. They conclude that the increased use of tobacco among young women in the past two to three decades is responsible for this dramatic change.

Clinical approach to graft hepatic artery thrombosis following living related liver transplantation

Hepatic artery thrombosis (HAT) has an occurrence rate of 1.7-26% following living donor liver transplantation (LDLT) and is one of the most common reasons for graft loss and mortality in this population. There is a higher incidence of HAT in pediatric recipients. The aim of this case report is to discuss clinical approaches for the treatment of HAT occurring in the early post-operative period after LDLT. An 11-month-old, 7.8-kg female with cirrhosis secondary to biliary atresia underwent LDLT at Gazi University Hospital in Ankara. The graft was a left lateral segment from her father with a left hepatic artery (HA) of 2 mm diameter and a graft weight/recipient body weight ratio of 2.0%. After an uneventful early post-operative period, HAT was diagnosed by Doppler ultrasonography (USG) on the fifth post-operative day. Following angiographic evaluation, immediate exploration and reanastomosis was performed using an operation microscope. Post-operatively, the HA was patented by Doppler USG and graft function returned to normal. Now, 42 months later, the patient continues to do well with normal graft function, using a regimen of tacrolimus monotherapy for immunosuppression. In countries which have very limited resources for urgent re-transplantation, given their serious donor shortage, graft salvage may be the only option for patient survival when HAT occurs. In these circumstances, early diagnosis and immediate revascularization may be the only method for graft salvage. A daily routine of Doppler USG examination in the early post-operative period may provide a method for the early diagnosis of HAT, before liver enzymes are elevated and hepatic necrosis has begun.

A new experimental flap model in the rabbit: scapular osteomyocutaneous flap

Despite the use of various types of osteomyocutaneous flaps in clinical practice, there are many unanswered questions regarding their basic physiology. Simple and reliable flap models are needed to investigate these problems. However, very few of these flap models have been described in small animals to date. The purpose of this study was to develop a new osteomyocutaneous flap model in the rabbit. Twenty adult New Zealand white rabbits, weighing 2.5 to 3.0 kg, were used in the reported experiment. In seven rabbits, the anatomy of the axillary vessels was studied by anatomic dissection and selective angiography. Based on this anatomic study, a new osteomyocutaneous flap, namely, the scapular osteomyocutaneous flap, is described in the rabbit model. The flap is composed of a skin island (16 x 8 cm) in the scapular region, the latissimus dorsi and intrinsic shoulder muscles, and the whole scapula as the bony component The flap is based on the axillary vessels, while the skin island and the latissimus dorsi muscle are independently supplied by branches of the thoracodorsal vessels. The flap could thus also be considered as a combined flap model. As an island flap, the flap was replaced in situ in eight rabbits, and transferred to the anterior chest in two rabbits. In the remaining three animals, the flap was transferred to the groin as a free flap. The viability of each component of the flap was demonstrated by direct observation, microangiography, bone scintigraphy, India ink injection study, and histologic examination. The authors concluded that the flap is a simple and reliable osteomyocutaneous flap model, since its dissection is easy; there is a long vascular pedicle with large vessel diameters; and large amounts of skin, muscle, and bone are included.

Alteration by Iloprost of the vasospastic effects of endothelin-1 in rabbit cerebral vessels

The reversal of endothelin-1 induced cerebral vasospasm with Iloprost was studied in the rabbit. Vasospasm in the basilar artery was evaluated by angiography; cerebral ischaemia by 'red-neurone-count' on light microscopy and morphological changes by electron microscopy. A potent antagonistic effect of Iloprost against ET-1 was observed in each of the parameters measured.

The New Double-Layer Micromesh Stent (Roadsaver®): Use in Endovascular Treatment of Supraaortic and Visceral Artery Aneurysms and Pseudoaneurysms

PURPOSE

This study was designed to present our preliminary experience with the Roadsaver^® double-layer micromesh (DLM) stent in the endovascular treatment of supra-aortic and visceral aneurysms and to utilize the flow-diverting effect of this new design in the treatment of these aneurysms.

METHODS

DLM stent (Roadsaver^®, Terumo, Tokyo, Japan) was used in five patients (median age 61.8 years; three men) for treating arterial aneurysms (one common carotid artery, one vertebral artery V1 segment, one superior mesenteric artery, and two renal artery aneurysms).

RESULTS

All stents were successfully deployed. Follow-up imaging with conventional catheter angiography or computed tomography showed successful treatment of all aneurysms.

CONCLUSIONS

The new DLM stent appears to be promising for the treatment of supra-aortic and visceral aneurysms.

Tuberculoma in the suprasellar cistern: possible CT--misinterpretation as aneurysm

A patient with multiple intracranial tuberculomas mimicking aneurysms is reported. The diagnosis was established by CT during the treatment of tuberculous meningitis. Anti-tuberculous therapy was continued until the radiological resolution of the lesions. A discussion of previous reports on the non-operative treatment of intracranial tuberculomas is included.

Endovascular stent-graft placement for the management of a traumatic axillary artery pseudoaneurysm-a case report

A 24-year-old woman with a right infraclavicular gunshot wound developed an axillary artery pseudoaneurysm. She was successfully treated by using a 5 cm Hemobahn stent-graft with a diameter of 6 mm. Postimplantation arteriography revealed normal flow through the axillary artery without evidence of leakage of contrast medium. Five months after the procedure, stenoses developed within the stent-graft owing to intimal hyperplasia and were treated by balloon angioplasty. The patient has been followed up symptom-free for 6 months after the second procedure.

Congenitally severe tortuous circumflex artery fistula draining into the coronary sinus: transcatheter closure with Guglielmi detachable coils via different delivery system

Coronary artery fistulae are very rare congenital anomalies which constitute 0.2-0.4% of all congenital heart diseases. The right chambers of the heart are the most frequent communication site of the coronary fistulae and may cause hemodynamic impairment in the coronary circulation. The fistulae arise frequently from right coronary and left anterior descending arteries. Fistulae from left circumflex artery are very rare. We report a case in which transcatheter embolization was performed with 3-mm Guglielmi detachable coils in a young adult with a rare type of congenital fistula originating from the circumflex artery and draining into the coronary sinus.

Angiotensinogen and Plasminogen Activator Inhibitor-1 Gene Polymorphism in Relation to Renovascular Disease

The present study was designed to evaluate angiotensinogen (AGT) M235T and plasminogen activator inhibitor-1 (PAI-1) (4G/5G) polymorphisims in relation to the occurrence of atherosclerotic renal artery stenosis (ARAS) and recurrent stenosis. In this study, 30 patients were enrolled after angiographic demonstration of ARAS; 100 healthy subjects for AGT polymorphism and 80 healthy subjects for PAI-1 polymorphism were considered the control group. The patients were followed for a mean 46.1 +/- 9.2 months. The patients had significantly higher frequencies of the MT genotype and the T allele than control group (chi(2) = 18.2, p < 0.001 and chi(2) = 11.5 p < 0.001). There were no significant differences in the PAI-1 genotype and allele findings when the data for all patients were compared with that for the controls (chi(2)= 2.45, p = 0.29 and chi(2) = 0.019, p = 0.89). There were no significant differences in the genotype and allele findings for the patients with and without restenosis (p > 0.05). The C-reactive protein (CRP) level was higher in the patients with restenosis than in the patients without restenosis (7.694 +/- 0.39 mg/L and 1.56 +/- 1.08 mg/L) (p = 0.001). Our results suggest that the M235T MT genotype and T allele might be associated with increased risk of atherosclerotic renal artery stenosis. The CRP level might be an independent predictor for recurrent stenosis.

Role of vena cava inferior filter on neurosurgical deep venous thrombosis

AIM

The patients who undergo neurosurgical procedures are at high risk for perioperative deep vein thrombosis and pulmonary embolism. Pharmacological prophylaxis with mechanic prophylaxis is a safe and effective way of preventing deep vein thrombosis and pulmonary thromboembolism in neurosurgery. However, pharmacological prophylaxis may increase the risk of hemorrhage after cranial or spinal operations.

MATERIAL AND METHODS

Patients with vena cava inferior filter were retrospectively examined between 2003 and 2010.

RESULTS

Approximately 1600 patients per year are operated in our clinic. Deep vein thrombosis incidence is % 1.2 - 2.3 in our department. Vena cava inferior filter is used on 13 patients who operated for various diagnoses, during the 2003 - 2010 period. None of these patients had new pulmonary thromboembolism after inserting vena cava inferior filter but two of them died cause of initial respiratory distress.

CONCLUSION

We think that vena cava inferior filter in is safe and effective method for pulmonary thromboembolism prophylaxis, especially for patients with high bleeding risk and who cannot be anticoagulated. Further prospective studies with larger series are needed for evaluating long term complications and benefits.

Computed tomographic ventriculography: a clinicoradiological study of 31 cases

We present 31 patients whose diagnoses were established by the aid of computed tomographic ventriculography. The indications for and diagnostic value of this method are reviewed.

Renal artery reconstruction in transplant kidney. Case report

A 30 years old female patient, to whom a cadaveric kidney transplantation was performed 7 years earlier, presented severe hypertension attacks for 2 years. Renal artery stenosis diagnosed by angiography, PTA could not be performed. She underwent an operation for surgical correction of stenosis and successful internal iliac renal artery anastomosis performed by saphenous vein interposition. The patient was discharged at the fourteenth postoperative day with excellent kidney function and stable blood pressure.

Computer assisted quantification of vasospasm on angiograms

We describe a new computer-based, automated method for the assessment of in vivo cerebral vasospasm. Arterial diameter measurements were performed on post-processed digital substraction angiographic images, using "pixel" as the unit. Vasospasm which was difficult to detect by visual inspection could be measured by the "stenosis quantification" program. A computer-assisted method such as we describe might decrease the risk of subjective errors.

Does thromboxane A2 synthase inhibitor UK-38485 prevent the vasoconstrictor effects of endothelin-1 on rabbit basilar artery?

Prevention of the production of thromboxane A2--a potent vasoconstrictor and aggregating metabolite of arachidonic acid--or infusion of the stable analogues of prostacyclin--which is another cyclo-oxygenase metabolite of arachidonic acid--has been shown to be beneficial in cerebral vasoconstriction. Endothelin-1, a peptide derived from endothelial cells, has been shown to induce a long-lasting cerebral vasoconstriction both in vivo and in vitro. The purpose of this study was to investigate the role of a novel thromboxane A2-synthase inhibitor UK 38485 on the acute vascular and morphological effects of Endothelin-1 applied intra-arterially on rabbit basilar arteries. The inguinal region of twenty four anaesthetized albino rabbits of both sexes were dissected and a catheter was inserted into the aorta via the femoral artery, for control angiography of the basilar artery and intra-arterial injection of ET-1 (0.25 ng total dose) and UK 38485 at a dose of 0.05 microgram kg-1 min-1 for 20 min or saline. Angiographic vasoconstriction quantification and morphological investigations of both vessels and brain stem either by light microscopy or transmission electron microscopy were the techniques applied for the study. We found out that, although the systemic administration of UK 38485 resulted in a potent antagonism of the acute vasoconstriction as visualized in angiographic studies, it did not affect the morphological changes induced by Endothelin-1 on the vessel wall. The results indicated that there might have been an interaction between Endothelin-1 and the prostaglandin synthesis mechanism in acute cerebral vasoconstriction.

Endovascular Treatment of Intracranial Anterior Circulation Aneurysms with Flow Diverters: A Single Centre Experience with mid and long-term results

AIM

We report our experience with flow diverter devices in the treatment of intracranial aneurysms arising from anterior circulation with mid and long-term follow-up.

MATERIAL AND METHODS

78 aneurysms in 61 patients (range 25-81 years, 13 male, 48 female) were treated with flow diverter devices. 40 (51,3%) aneurysms were treated with pipeline embolization device (PED), 24 (30,8%) aneurysms were treated with SILK stent, 12(15,4%) aneurysms were treated with flow redirection endoluminal device (FRED) and two aneurysms were treated with P64 Flow Modulation Device (P64). Angiographic follow-up data at six month and one yea were recorded and the occlusion degrees of aneurysms were evaluated according to the scale which was formed by Kamran et al.

RESULTS

At six month follow-up, complete occlusion (grade 4) rate was 60,8% and at one year increased to 74,3%. Statistical analysis revealed significant difference (p=0,002) between six month and one year follow-up results but there was no significant association (p=0,531, p=1,000) between aneurysm occlusion rate and aneurysm diameter. Two patient (3,2%) died due to hemorrhagic complication.

CONCLUSION

Endovascular treatment of intracranial anterior circulation aneurysms with flow diverters is a safe and effective treatment option. A high rate of stable occlusion is achieved at long term follow-up.

Intravenous and local intraarterial tissue-plasminogen activator in a rabbit model of acute thromboembolic stroke: angiographic comparison

The aim of early thrombolytic therapy in acute stroke is to obtain early recanalization of occluded cerebral arteries and prevent or reduce irreversible ischemic brain damage. In this study, Seldinger technique and digital subtraction angiography were used to verify thromboembolic occlusion of the common carotid artery by an autologous 12-hour-old thrombus in 28 rabbits. Thirty minutes after embolization, 2 mg/kg of recombinant tissue-plasminogen activator (rt-PA) was delivered intravenously by way of the femoral vein in group A (n = 8) and through a local intraarterial infusion in group B (n = 8). Twelve control animals received an equivalent volume of saline intravenously (group C, n = 6) or by local intra-arterial infusion (group D, n = 6). A comparison of posttreatment angiographs of the treatment groups and the control groups was used to demonstrate reperfusion induced by thrombolytic therapy. None of the control animals showed any evidence of recanalization. Both intravenously (group A) and intra-arterially (group B) treated animals achieved 100% recanalization, although the average time to recanalization was significantly longer in group A (P = .01; 123.7 vs 82.5 min). These results suggest that local intra-arterial administration of rt-PA within 30 minutes produces more rapid reperfusion compared with the intravenous route. Further studies and additional treatments are needed to widen the therapeutic window and decrease hemorrhagic side effects.

Effect of a chloride channel inhibitor, 5-nitro-2- (3-phenylpropylamino)-benzoate, on endothelin-1 induced vasoconstriction in rabbit basilar artery

AIM

Endothelin-1 (ET-1) has been implicated in the pathophysiology of cerebral vasospasm. Chloride (Cl-) channels exist in vascular smooth muscle and activation of these channels leads to depolarization and contraction. The aim of the present study was to test the effect of 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), a Cl- channel antagonist, on the ET-1-induced cerebral vasospasm in rabbit basilar artery and thus investigate the contribution of Cl- channels.

MATERIAL AND METHODS

Thirty rabbits were divided into five groups and received intra-arterial injection of isotonic saline (Group I, n=6), ET-1 (group II, n=6), ET-1 plus NPPB (Group III, n=6), dimethylsulfate (DMSO4) (Group IV, n = 6) and NPPB (Group V, n=6). Pre and post injection basilar artery diameters were measured in each group and transmission electron microscopic investigations on basilar arteries were performed.

RESULTS

The mean pre-injection and post-injection vessel diameters were 0.8833 mm and 0.7000 mm in ET-1 group, 0.6833 mm and 0.8500 mm in ET-1 + NPPB group. NPPB administered prior to ET-1 injection, prevented the ET-1-induced vasoconstriction. Additionally, NPPB prevents the ET-1 induced changes in vessel wall and neurons in the brain stem.

CONCLUSION

The results of this study add further insights to our armamentarium against cerebral vasospasm.