Acute MR Research Articles

Abstract 3051: Percutaneous Repair of Functional Mitral Regurgitation Using CARILLON ™ Mitral Contour System. Acute Transesophageal Echocardiography Results from AMADEUS ™ Trial

Left ventricular dilatation with subsequent mitral insufficiency exacerbates heart failure. New techniques for percutaneous repair of Functional Mitral Regurgitation (FMR) are being developed to minimize the high procedural risk of conventional cardiac surgery therapies. To evaluate the feasibility and procedural safety of percutaneous mitral valve repair with CARILLON ™ Mitral Contour System ™ (Cardiac Dimensions® Inc.) in FMR patients AMADEUS ™ trial has been designed. Patients with FMR of both ischemic and non-ischemic origin were enrolled to this multicenter phase I trial. The device is implanted into the coronary venous system and applies tension to the mitral ring in order to improve coaptation of the leaflets. Transesophageal echocardiography (TEE) was used to assess the MR changes. Acute procedural data, obtained in the cath lab immediately before and after the procedure, are reported. Percutaneous mitral annuloplasty in patients with FMR and dilated cardiomyopathy resulted in acute MR reduction (grade 3.0±0.6 to 2.0±0.8, p<0.0001) and permanent device implantation in 30 out of 43 attempts. Additional measurements in final 20 implanted patients showed reductions in vena contracta (0.69±0.29 cm to 0.46±0.26 cm, p<0.0001), effective regurgitant orifice area (0.33±0.17 cm 2 to 0.19±0.08 cm 2 , p<0.0001), regurgitant volume (40±20 ml to 24±11 ml, p= 0.0005), and jet area/left atrial area (45±13% to 32±12%, p<0.0001). Coronary arteries were crossed in 36 patients (84%), but arterial compromise contributed to lack of implantation in 6 patients (14%). All unsuccessful implants were recaptured and removed in these patients without procedural complications. Permanent implantation of the device is safely achievable in the majority of eligible patients resulting in acute MR reduction. Arteries are crossed in most patients and without significant impact. Phase two trials including long term clinical observations on larger number of patients are needed to asses the clinical value of the technique.

Acute MR imaging compared with bone scintigraphy in suspected scaphoid fractures: SOS (Study of Occult Scaphoid) fractures

Acute MR imaging compared with bone scintigraphy in suspected scaphoid fractures: SOS (Study of Occult Scaphoid) fractures

Methanol poisoning: acute MR and CT findings in nine patients

Methanol poisoning is an uncommon but potent central nervous system toxin. We describe here the CT and MR findings in nine patients following an outbreak of methanol poisoning. Five patients with a typical clinical presentation and elevated anion and osmolar gaps underwent conventional brain MRI with a 1.5-T Gyroscan Interna scanner. In addition nonenhanced CT was performed in another three patients with more severe toxicity. Bilateral hemorrhagic or nonhemorrhagic necrosis of the putamina, diffuse white matter necrosis, and subarachnoid hemorrhage were among the radiological findings. Various patterns of enhancement of basal ganglial lesions were found including no enhancement, strong enhancement and rim enhancement. A good knowledge of the radiological findings in methanol poisoning seems to be necessary for radiologists. The present study is unique in that it enables us to include in a single report most of the radiological findings that have been reported previously.

MR spectroscopy: Predicting long‐term neuropsychological outcome following pediatric TBI

To identify useful acute indicators of long-term neurocognitive outcome beyond clinical variables for children and adolescents treated for a traumatic brain injury (TBI). The efficacy of magnetic resonance spectroscopy (MRS) acquired 6+/-4 days after TBI in 20 children/adolescents in predicting intellectual and neuropsychological functioning one to four years post injury was assessed. Short echo-time single voxel MRS (SVS) from normal-appearing brain was compared to intermediate echo-time multivoxel MR spectroscopic imaging (MRSI) from normal-appearing and visibly-injured brain acquired through the level of the corpus callosum (CC). N-acetyl aspartate (NAA) was moderate to strongly correlated with cognitive scores. Mean NAA/creatine (Cre) from MRSI alone explained over 40% of the variance in cognitive scores and 18% of the variance above and beyond demographic and clinical variables alone. Mild to moderate associations were noted between SVS metabolites (glutamate/glutamine [Glx] and myoinositol [mI]) and cognitive scores, with no such associations apparent for choline (Cho) or Cre. Exploratory analyses revealed trends for regional neuroimaging data and specific cognitive abilities. Acute MR spectroscopy of the pediatric brain injury patient improves prognostic ability and may provide valuable information for early treatment and intervention planning.

Imaging in acute stroke

Stroke is a syndrome characterized by a sudden neurological deficit caused by intracranial hemorrhage or ischemia. Computed tomography (CT) maintains a primary role in the evaluation of patients with acute stroke. The optimal magnetic resonance imaging (MRI) protocol in acute stroke includes diffusion-weighted imaging (DWI) to show acute ischemic lesion and MR perfusion study to estimate brain perfusion. Careful selection of patients for a thrombolytic therapy is crucial to improve safety and efficacy.

A CANINE MODEL OF CHRONIC MITRAL VALVE REGURGITATION WITH PRESERVATION OF RESTING CARDIAC FUNCTION

Background: The purpose of this study was to develop a canine model of chronic dilated cardiomyopathy with preservation of resting cardiac function. Methods: The baseline cardiac geometry and function of eight mongrel dogs (20–22 kg) were evaluated using transthoracic echocardiography (TTE). A right atrial pacer lead was implanted, and mild MR was produced through a fixed lesion to the mitral valve apparatus. Incremental pacing induced LV dilation over an eight-month period. The pacer was deactivated and the dogs followed for an additional six weeks. The heart was arrested in diastole and myocytes were examined histo-logically. All animals were evaluated in-vivo at baseline, following acute MR, at the end of pacing and at explant. TTE evaluations were performed hi-weekly. Similar studies were performed in six control dogs. Results: TTE data demonstrated significant changes in LV and LA geometry, which were sustained following pacing deactivation. MR severity increased significantly, whereas baseline cardiac function was preserved. There was preservation of stroke volume and systemic pressures with a significant increase in pulmonary capillary wedge pressure. Cardiac function decreased significantly at increased pacing rates. Isolated myocytes demonstrated significant cellular enlargement from control studies with increased cell area and volumes. Conclusion: The methodology presented represents a novel model of chronic MR with preservation of baseline cardiac function. Our results demonstrate progressive cardiac remodelling and worsening MR without significant changes in EF or stroke volume.

MR imaging of a severe cervical fracture-dislocation after traumatic delivery

We present the acute MR findings in an infant with a complicated traumatic delivery, asphyxia, spinal cord injury, and a radiographically apparent cervical spine fracture-dislocation. MRI including diffusion-weighted imaging allowed early characterization and localization of the extent of spinal cord injury.

Usefulness of Proton MR Spectroscopy in Acute Cerebral Infarction: An Experimental and Clinical Study

Purpose : To evalvate the usefulness of single-voxel localized proton MR spectroscopy(MRS) in monitoring changes in cerebral metabolites in cases of acute cerebral infarction. Materials and Methods : In 15 cats with common carotid artery occlusion and 21 patients with acute cerebral infarction T2-weighted (T2WI), diffusion-weighted (DWI), and MR spectroscopic images were obtained at var-ious times after stroke onset. Results : In the cat model, Lac and α-Glx levels increased as early as 30minutes after vascular occlusion and continued to increase for a further 2 hours. The remaini ng metabolites, NAA, Cho, mI, and ,-Glx, showed no significant change. During clinical study, increases in Lac and ,-Glx, and decreases in NAA were detected three hours after stroke onset. These metabolites continued to change until 72 hours had e-lapsed. The remaining metabolites, Cho, mI, and -Glx tended to be constant. Conclusion : MRS is capable of measuring and monitoring the metabolites involved in acute cerebral infarc-tion. MRS may play an important role in the investigation of pathophysiology as well as in the early diagnosis of acute cerebral infarction.

An Indian dilemma

Raj, a 4-day-old baby, has not urinated since birth. Dr Jha gently refers his distraught mother to a paediatrician. Nina is 21 years old and has a breast abscess. Dr Jha tells her he will operate on the abscess in the morning, notices her blanched look, rightly guesses her fear, and reassures her that it is not cancer. I suddenly notice an old schoolfriend sitting across the room from me. She unwraps her scarf to reveal a large dressing on her neck. A recently drained tuberculous abscess discharges pus. While Dr Jha examines her wound, our eyes meet. I am embarrassed to meet her under such conditions and leave the room. On returning, I ask Dr Jha whether clean and well-nourished people can get tuberculosis; the sight of a schoolfriend with tuberculosis has shaken me, as if I expected all those who I know to be free from disease. He replies that tuberculosis is very common throughout India and no one is spared. One of the theatre staff arrives to tell Dr Jha that the theatre is ready for Mr Lal’s cholecystectomy. The rest of the throng outside must wait, most of whom have travelled long distances, many on foot, to seek treatment here. Word has spread far about Dr Jha, who, after finishing at the top of his medical class, went to the UK for specialist training and then returned to India. He cares for his own people. At least half the waiting patients will have a non-surgical complaint, but in India there is no medical system to channel patients to appropriate specialists. Dr Jha is first a general practitioner and then a surgeon, as well as physician, paediatrician, obstetrician, and gynaecologist when needed. Dr Jha rolls up his trousers and shirt sleeves, discards his tie, scrubs up, dons a sterile gown and gloves, and walks into theatre. There is a combination of clean and unclean, qualified and unqualified in the theatre. Although the surgeon wears a sterile gown and uses autoclaved equipment, there are six other people present in civilian clothing. The ward is next to the theatre and the attendants walk freely between the two areas. The theatre door is wide open and one of the ubiquitous houseflies finds its way in; someone reaches quickly for the Baygon spray, filling the room with its intolerable smell. The anaesthetist has been working in this clinic for the past 3 years. Before his arrival, a man with no medical background, personally trained by Dr Jha, carried out all anaesthetic duties, and he still assists when the anaesthetist is unavailable. The other attendants, all without medical training, are familiar with different antibiotic regimens, the various intravenous solutions used, and the general care of patients. This clinic works 365 days a year. Thousands of patients go through its doors, and they share between them just three medically qualified practitioners. Bhagalpur, Bihar, India 2200 h, Dec 4, 1996 I stand by the bedside, holding his hand as he writhes in pain. In the dim candle-light, I notice his bare feet, hardened by years of walking unprotected through sun and rain, his hands callused, scarred, and capped by black nails, his dirty torn kurta, and old khaki pants. I take in the agonised look on his face, the trickle of blood at the corner of his mouth where he has just bitten his lip. I am in the private clinic of Dr Jha, on an elective in India at the end of my fifth year of medical school at Monash University, Melbourne, Australia. Dr Jha is still working in his office so we sit down for a chat. That is when Mr Lal is carried in by his wife and brother. In whispered conversation with his wife, she tells me how Mr Lal was pulling his rickshaw when he suddenly felt a pain in his abdomen. Fortunately, he had been close enough to return home, where he collapsed. His brother and wife had taken him by rickshaw to the local hospital, only to find that the power supply had been cut off, there was a shortage of medications and equipment, and at that time of night help was unavailable. It is now 3 hours since the pain began. Dr Jha diagnoses acute cholecystitits, prescribes analgesia, and admits Mr Lal to the clinic for a cholecystectomy.

Frequency of unexpected multifocal metastasis in patients with acute spinal cord compression. Evaluation by low-field MR imaging in cancer patients.

The aim of the study was to estimate, in an acute care service, the frequency of multiple-level lesion involvement in patients with clinically suspected spinal cord compression or spinal blockage. Over a period of 17 months, 240 patients with symptoms of acute spinal cord compression underwent acute MR examination of the spine in a 0.1 T MR unit. The cervical spine was only added to the examination if there was clinical suspicion of cord compression above Th1. In 65 (27%) of the 240 patients, involvement of at least one level was found. Of these patients, 32 (49%) showed involvement of more than one level. This high rate was surprising, since only 14 (44%) of the 32 multiple lesions had been clinically suspected. There was no correlation to age or original type of cancer. MR accurately demonstrates the anatomy of the spine and spinal cord, showing the level and complexity of spinal lesions. Multiple lesions may be underestimated when the combination of myelography/radiculography and CT is used.

Low-Field MR Imaging (0.1 T) in Patients with Clinically Suspected Acute Spinal Block

The diagnostic usefulness of a 0.1 T MR unit in patients with clinical suspicion of acute spinal block was studied in 59 patients who were referred to acute MR investigation. The records were reviewed retrospectively 1 month after the MR for assessing the clinical impact of the examination. Ninety-eight per cent had a true-positive examination confirmed by surgery (21%) or observation (77%). In 60% of the patients the MR imaging had a therapeutic consequence. In only one patient did the level of visualised pathology at the MR examination not correlate with the clinical findings; the patient subsequently refused surgical treatment. We conclude that a low-field MR unit is excellent for acute examination of patients clinically suspected of acute spinal block.

Low-Field MR Imaging (0.1 T) in Patients with Clinically Suspected Acute Spinal Block

The diagnostic usefulness of a 0.1 T MR unit in patients with clinical suspicion of acute spinal block was studied in 59 patients who were referred to acute MR investigation. The records were reviewed retrospectively 1 month after the MR for assessing the clinical impact of the examination. Ninety-eight per cent had a true-positive examination confirmed by surgery (21%) or observation (77%). In 60% of the patients the MR imaging had a therapeutic consequence. In only one patient did the level of visualised pathology at the MR examination not correlate with the clinical findings; the patient subsequently refused surgical treatment. We conclude that a low-field MR unit is excellent for acute examination of patients clinically suspected of acute spinal block.