17O-decoupled (1)H spectroscopy and imaging with a surface coil: STEAM decoupling.

(17)O-decoupled (1)H spin-echo imaging has been reported as a means of indirect (17)O detection, with potential application to measurement of blood flow and metabolism. In its current form, (17)O decoupling requires large RF amplitudes and a 180 degrees refocusing pulse, complicating its application in volume and surface coils, respectively. To overcome this problem, we have developed an (17)O-decoupled proton stimulated echo sequence ("STEAM decoupling") to allow (17)O detection with a surface coil. A high B(1) amplitude is easily generated, allowing complete decoupling of (17)O and (1)H. Slice-selective, (17)O-decoupled (1)H imaging is readily performed and the sequence is easily adapted for localized spectroscopy. Intrinsic correction for variations in B(1) and further compensation for B(1) inhomogeneity are discussed.

Sodium visibility and quantitation in intact bovine articular cartilage using high field (23)Na MRI and MRS.

Noninvasive methods of detecting cartilage degeneration can have an impact on identifying the early stages of osteoarthritis. Accurate measurement of sodium concentrations within the cartilage matrix provides a means for analyzing tissue integrity. Here a method is described for quantitating sodium concentration and visibility in cartilage, with general applications to all tissue types. The sodium concentration in bovine patellar cartilage plugs was determined by three different methods: NMR spectroscopy of whole cartilage plugs, NMR spectroscopy of liquefied cartilage in concentrated HCl, and inductively coupled plasma emission spectroscopy. Whole bovine patellae were imaged with relaxation normalized calibration phantoms to ascertain sodium concentrations inside the articular cartilage. Sodium concentrations in intact articular cartilage were found to range from approximately 200 mM on the edges to approximately 390 mM in the center, with an average of approximately 320 mM in five separate bovine patellae studied. In essence, we have created sodium distribution maps of the cartilage, showing for the first time, spatial variations of sodium concentration in intact cartilage. This average concentration measurement correlates very well with the values obtained from the spectroscopic methods. Furthermore, sodium was found to be 100% NMR visible in cartilage plugs. Applications of this method in diagnosing and monitoring treatment of osteoarthritis are discussed.

Sodium MRI of human articular cartilage in vivo.

Preliminary results from in vivo sodium MRI of human patellar articular cartilage are presented. Sodium images generated of an in vitro bovine patella clearly distinguish the region of proteoglycan depletion from the region of healthy cartilage. This provides the first evidence that sodium imaging may be used to detect changes due to osteoarthritis in vivo. The process of optimizing imaging time and signal-to-noise ratio, as well as potential implications in the detection of osteoarthritic change, are discussed.

Congenital aneurysm of the internal jugular vein in a pregnant woman.

A pregnant woman with a symptom-free congenital aneurysm of the internal jugular vein (IJV) is described. A color duplex scan revealed an aneurysm (2.4 cm in diameter) of the right IJV in the mid-neck without evidence of thrombus. To the authors' knowledge, this is the first reported case demonstrating that such a lesion in a pregnant woman can be safely managed without excision.

Venous aneurysms: surgical indications and review of the literature.

BACKGROUND: During the last 20 years we diagnosed five cases of venous aneurysm of the jugular (n = 4) and basilic (n = 1) veins. The purpose of this report was to determine the natural history and indications for surgery of venous aneurysms. METHODS: Our five cases were included in an English-language literature review performed through August 1993. RESULTS: In our series two aneurysms (one external jugular vein, one basilic vein) were excised for cosmetic reasons. Three internal jugular vein aneurysms were followed up for up to 4 years without complications with serial color duplex ultrasonography. Of 32 patients with abdominal venous aneurysms (18 portal, seven inferior vena cava, four superior mesenteric, two splenic, one internal iliac), 13 (41%) had major complications including five deaths. Of 31 patients with deep venous aneurysms of the extremity (29 popliteal, two common femoral), 22 (71%) had deep vein thrombosis or pulmonary embolism and in 17 recurrent deep vein thrombosis or pulmonary embolism developed when patients were treated with anticoagulation alone. CONCLUSIONS: Prophylactic surgery is cautiously recommended for low-risk patients with venous aneurysms of the abdomen and strongly recommended for most patients with lower extremity deep venous aneurysms. Other venous aneurysms should be excised only if they are symptomatic, enlarging, or disfiguring.

Pulmonary risk factors of elective abdominal aortic surgery.

PURPOSE: The purpose of this study was to retrospectively identify risk factors for postoperative pulmonary complications in patients undergoing elective abdominal aortic surgery via a midline incision. METHODS: We reviewed 181 consecutive patients who underwent operation between July 1986 to December 1992. Preoperative factors analyzed included age, sex, diabetes mellitus, history of smoking, chronic obstructive pulmonary disease, obesity, indication for surgery (aneurysm [126] or aortoiliac occlusive disease [AIOD] [55]), history of coronary artery disease, length of preoperative hospital stay, American Society of Anaesthesiologists class, and pulmonary function tests. Intraoperative factors analyzed included endotracheal tube diameter, percent of inspired oxygen, blood loss, blood and crystalloid replacement, total operative time, epidural analgesia, and stress ulcer prophylaxis. RESULTS: Although the operative mortality rate was only 1.7% (3 of 181), major pulmonary complications occurred in 29 (16%) patients, including two lung-related deaths. Pneumonia occurred in 17 (9%) patients, prolonged intubation greater than 24 hours occurred in nine (5%), and reintubation caused by pulmonary insufficiency occurred in three (2%). On univariate analysis, the following were associated with major pulmonary complications (p < 00.05): American Society of Anaesthesiologists class IV, age greater than 70 years, ideal body weight greater than 150%, forced vital capacity of 80% or less predicted, forced expiratory flow rate (25 to 75) of 60% or less predicted, crystalloid replacement greater than 6 L, and total operative time greater than 5 hours. CONCLUSIONS: The presence of these pulmonary risk factors, notably increased age and weight, decreased forced vital capacity and forced expiratory flow rate (25 to 75), and expected prolonged operative time, influences our decision not to proceed with surgery for small aortic aneurysms or for AIOD causing claudication. Patients at high pulmonary risk with AIOD who require revascularization for limb salvage would be more likely to undergo extraanatomic bypass. Pulmonary risk factors may play as important a role as cardiac factors in elective aortic surgery.