Temporal changes in the oxidation state in in vitro blood.

The rates at which the paramagnetic compounds deoxyhemoglobin (Hb) and methemoglobin (MHb) form in vivo within an area of hemorrhage are unknown. The present experiment establishes the baseline concentrations and rates of change in paramagnetic hemoglobin concentrations, as well as the pH in normal heparinized and clotted human blood maintained in vitro at 37 degrees C under anaerobic conditions over 30 hours. There was a moderate increase in Hb concentration in normal heparinized blood (average increase was 15.5%, rate = 0.50%/hour) and a slight increase in MHb concentration in the heparinized blood and clots (average increase was 1.4%, rate = 0.044%/hour). A second experiment was done to verify the activity of the RBC systems responsible for maintaining the hemoglobin molecule in the reduced state. Conversion of MHb to Hb in these samples proceeded at a rate of 5.6%/hour. In a third experiment, blood from 11 normal subjects maintained at 4 degrees C 25 degrees C was analyzed for MHb concentration over the course of 28 days. The level of MHb formation remained in the range of normal for at least 11 days in all subjects. The authors conclude that at basal conditions created in vitro, the blood levels of both Hb and MHb remain at relatively low levels. Therefore, if the accumulation of Hb and/or MHb occurs in acute in vivo hematomas it must be driven by intrinsic tissue factors.

Pathophysiology of acute intracerebral and subarachnoid hemorrhage: applications to MR imaging.

In this review of the pathophysiology of acute intracerebral and subarachnoid hemorrhage, information from several disciplines is assembled to describe the bleeding process, hemostasis and coagulation, fibrinolysis, erythrocyte lysis, phagocytosis, and changes in the state of hemoglobin. The impact of these pathophysiologic processes upon MR imaging, CT, and angiography is noted.

Chordomas: their CT appearance in the cervical, thoracic and lumbar spine.

We reviewed 25 CT scans of 21 patients who had chordomas in the cervical, thoracic, or lumbar spine. Nine patients were studied at the time of initial presentation and 12 after tumor recurrence. All scans showed vertebral body destruction coupled with an associated soft tissue mass located anteriorly or laterally. Additional CT findings included septated areas of low attenuation within the tumor, amorphous soft tissue calcification, tumor extension into the spinal canal, disk space involvement, and contrast enhancement.

Prophylactic diazepam in prevention of contrast media-associated seizures in glioma patients undergoing cerebral computed tomography.

Five milligrams of intravenous diazepam given prior to contrast media injection statistically significantly reduced the incidence of contrast media-associated seizures from 16% to 2% in a prospective, randomized series of glioma patients. Factors related to increased risk of contrast media-associated seizures are (1) prior seizure history due to glioma and/or prior contrast media and (2) prior or concurrent brain antineoplastic therapy. Factors not related to an increased risk of contrast media-associated seizures are (1) contrast media dosage, (2) type or grade of glioma, and (3) computerized tomographic appearance of the glioma. Theories regarding the etiology of contrast media-associated seizures are discussed.

Interventional radiologic procedures in the renal transplant.

Percutaneous interventional procedures can be valuable in the evaluation and treatment of urologic complications of renal transplantation. Thirty-three patients underwent percutaneous procedures, including relief of obstruction by catheter nephrostomy, diagnostic antegrade pyelography with Whitaker testing, aspiration of various fluid collections (lymphocele, hematoma, urinoma, and abscess), and renal artery angioplasty, during a three year period at three institutions, to provide temporizing treatment and anatomic data. Surgical intervention was sometimes avoided, but more often it could be deferred to allow the patient to stabilize prior to surgery. Complications that required surgery occurred in two patients.

Impermeability of the blood-brain barrier to intravenous high-iodine-dose meglumine diatrizoate in the normal dog.

The effect of an intravenous bolus of 4.3 ml/kg of 60% meglumine diatrizoate on the blood-brain barrier (BBB) was studied in five adult unanesthetized dogs. Intravenous 3% Evans blue dye (4 ml/kg) was used as an indicator of BBB disruption. The animals were observed for signs of neurotoxicity for 1 hr after contrast-medium injection and then sacrificed. Their brains were removed and sectioned. None of the dogs displayed clinical evidence of neurotoxicity, and none of the brain specimens showed evidence of BBB disruption. The authors concluded that there is a statistically significant lack of correlation between the intravenous administration of 4.3 ml/kg of 60% meglumine diatrizoate and BBB disruption (p less than 0.05 with a probability of 90%). A previous publication reported focal BBB disruption in anesthetized dogs with dosages of 4 ml/kg and 6 ml/kg of 60% intravenous contrast agent given as an initial bolus followed by a drip infusion. The present study duplicated this prior experiment using the 6 ml/kg dose followed by infusion in three additional unanesthetized dogs and failed to substantiate the previous findings. This discrepancy leads to the assumption that the BBB damage noted in the previous experiment was somehow related to a factor(s) other than the intravenous contrast-medium injection. The BBB cannot be disrupted in the unanesthetized dog with intravenous doses of 60% contrast media of even 6 ml/kg.

Non-small cell lung carcinoma adrenal metastases. Computed tomography and percutaneous needle biopsy in their diagnosis.

One hundred seventy-two consecutive patients with non-small cell lung carcinoma underwent adrenal computed tomography (CT) as part of their initial staging evaluation. Twenty of these patients (12%) had either unilateral or bilateral adrenal masses detected by CT. Six of these 20 patients had distant metastases at other sites and the adrenal masses were presumed to be metastases. Fourteen of the 20 patients, without other evidence of distant metastases at the time of CT, underwent percutaneous 22-gauge needle biopsy of the adrenal masses. The results of the biopsies diagnosed lung carcinoma metastases in 13 patients and a primary adrenal tumor in 1 patient. An additional 32 patients with normal adrenal glands by CT criteria underwent percutaneous 22-gauge needle biopsy of their morphologically normal glands. In four of these patients (12%), the results of CT-guided biopsy diagnosed lung carcinoma metastases. The role of CT and percutaneous needle biopsy in diagnosing non-small cell lung carcinoma metastases to the adrenal glands is discussed.

A technique for preparation, removal, and storage of cadaver spine specimens for CT evaluation.

A technique for alleviating artifacts in excision of cadaver spines for computed tomographic (CT) study is described. It maintains distension of the thecal sac by filling the spinal subarachnoid space with gelatin containing iodinated contrast media. The excision, handling, and storage procedures described prevent all but minute amounts of air from entering the specimen and producing artifacts which can degrade the CT images. The frozen specimen can be sectioned with a band saw in any plane and correlated with the CT images. This technique allows CT-anatomic correlation of not only bony and extrathecal soft tissues of the spine, but also the intrathecal neural elements.

Hyperdense renal masses: a CT manifestation of hemorrhagic renal cysts.

Eleven patients with sharply circumscribed round to ovoid renal cysts measuring 70-90 H on CT are reported. The cysts were hyperdense on unenhanced scans, measuring 30-60 H greater than the adjacent parenchyma, and either hypodense, isodense, or hyperdense on enhanced scans. Four patients had polycystic kidney disease; of the other 7 patients, the cysts were cortical in 6 and parapelvic in 1. Eight patients had a solitary cyst and 3 had multiple cysts. Sonography demonstrated internal echoes and/or lack of increased through-transmission in 6 patients. Pathological analysis was available in 6 cases and indicated a benign, hemorrhagic renal cyst. This hyperdense CT appearance is characteristic of some hemorrhagic renal cysts, though differentiation between benign and malignant cysts requires cyst puncture and/or surgery.

Concentration of intrathecal 3H-labeled metrizamide in normal dog brain: age-related differences.

Responses to intrathecal metrizamide in dogs were found to be age-related: Adult dogs had seizures; 7-week-old dogs appeared stuporous; 6-day-old dogs were clinically unaffected. The brain metrizamide concentrations 4, 6, and 20 hr after intrathecal injection correlated directly with the occurrence and severity of neurotoxic symptoms. Age-related differences in brain metrizamide concentration may be explained by two factors. The first is the failure of current clinical guidelines to adjust the recommended dosage of metrizamide to reflect differences among age groups in brain weight rather than body weight. This error resulted in lower doses/gram of brain weight being given to the puppies. However, the large differences in brain metrizamide concentrations among the three groups of dogs could not be explained solely by differences in the dose. A second factor, physiologic age-related differences in brain penetration, is believed to be operative. The precise nature of these differences is unclear.

Biopsy of focal hepatic lesions. Comparison of 18 and 22 gauge needles.

One hundred consecutive patients underwent CT-guided percutaneous biopsy of focal non-cystic hepatic lesions using 18 and 22 gauge needles. The overall accuracy rate was 98% for the 18 gauge needle (92 true positives, 6 true negatives, 2 false negatives) and 84% for the 22 gauge needle (79 true positives, 5 true negatives, 4 false negatives, 12 with inadequate cellular material). There were no complications with either needle. The major advantage of the 18 gauge needle was its more consistent retrieval of adequate cellular material. CT with bolus contrast enhancement and rapid-sequence scanning facilitates avoidance of hypervascular lesions and hemangiomas, thereby adding to the safety of the technique.

Solid renal mass in the cancer patient: second primary renal cell carcinoma versus renal metastasis.

Most renal metastases are asymptomatic, occur with widespread metastatic disease, and are too small to be detected with computed tomography (CT). Rarely they form large masses. These are typically angiographically hypovascular and show only minimal CT contrast enhancement. Renal carcinoma as a second primary malignancy in the cancer patient is 4.5 times more common than mass-like renal metastases and demonstrates two CT contrast enhancement patterns. The latter include either minimal enhancement or irregular regions of intense enhancement. These CT contrast enhancement patterns of both renal carcinoma and metastasis can be used to direct the further diagnostic evaluation of these masses and distinguish between a renal metastasis or a second primary renal carcinoma in the cancer patient.

Computed tomography of a thrombosed left anterior vena cava.

A case of transposed (left) inferior vena cava (IVC) with a normal suprarenal IVC visible on computed tomography (CT) is presented. There is concomitant recanalized thrombosis of the left IVC with venous collaterals present. Caval anomalies, differential diagnosis of a left IVC, and CT demonstration of thrombosis of major abdominal venous structures and associated venous collaterals are discussed.

Normal adrenal glands in small cell lung carcinoma: CT-guided biopsy.

Twenty-four small cell lung carcinoma patients with morphologically normal adrenal glands by computed tomographic (CT) criteria underwent percutaneous thin-needle biopsy of their adrenal glands. Of 43 glands biopsied, 29 had adequate cellular material for interpretation. Five (17%) of the 29 glands were positive for metastases; the rest had negative biopsies. This series indicates an approximate 17% false-negative diagnosis rate by CT when staging the adrenal glands in patients with small cell lung carcinoma. It also demonstrates the utility of percutaneous needle biopsy as an investigational tool to further evaluate normal-sized adrenal glands in the oncologic patient.

Diazepam prophylaxis of contrast media-induced seizures during computed tomography of patients with brain metastases.

The effect of 5 mg of intravenous diazepam (Valium) on contrast media-associated seizure incidence was studied in a randomized controlled trial involving 284 patients with known or suspected brain metastases undergoing cerebral computed tomography. Of these patients, 188 were found to have brain metastases, and it is estimated that for this subgroup prophylactic diazepam reduces the risk of contrast-associated seizure by a factor of 0.26. Seizures occurred in three of 96 patients with metastases on diazepam and in 14 of 92 patients with metastases but without diazepam. Factors related to increased risk of contrast media-associated seizures are: (1) prior seizure history due to brain metastases and/or prior contrast, (2) progressive cerebral metastases, and (3) prior or concurrent brain antineoplastic therapy. Factors not related to an increased risk of these seizures are: (1) contrast media dosage, chemical composition, or osmolarity, (2) computed tomographic appearance of metastases, and (3) type of primary malignancy. Concomitant therapeutic levels of diphenylhydantoin (Dilantin) do not protect completely against contrast media-associated seizures. Pathophysiology of contrast media-associated seizures is discussed in view of the risk factors determined by this study.

Intrahepatic vascular territories shown by computed tomography (CT). The value of CT in determining resectability of hepatic tumors.

Hepatic vascular anatomy as seen on computed tomography (CT) is correlated with surgical planes. The portal triad structures course in an intralobar and intrasegmental direction but are bounded by interlobar and intersegmental surgical planes which are traversed by the hepatic veins. All of these vessels and planes are oriented cephalocaudally and are shown well on axial CT images following a bolus contrast injection or a combination bolus and drip infusion (80 g I). In a prospective survey of 24 partial hepatectomy candidates evaluated by this technique, with angiographic or surgical corroboration in 15, CT accurately established lack of resectability in 11 patients and was correct in 11 of 13 patients whose tumor was considered resectable. Angiography and surgery may be averted in some partial hepatectomy patients using this technique.

Pancreatic Castleman disease simulating pancreatic carcinoma on computed tomography.

A patient with a pancreatic body and tail mass caused by Castleman disease and visible on computed tomography is described. This entity simulated pancreatic carcinoma in this clinical setting. Theories of etiology of Castleman disease and differential diagnosis of pancreatic masses are discussed. Proper examination technique is stressed.

Nephrotoxicity of epinephrine-assisted venography.

A retrospective study was performed to determined the nephrotoxicity of epinephrine-assisted venography (EAV). The results showed an increase in the serum level of creatinine (sCr) up to five days after EAV in 67% of patients, in comparison with 16% in patients who had other types of renal angiography. Microscopic examination of renal specimens from patients who had undergone EAV showed vacuolization of the epithelial cells of the proximal tubules. Risk factors for acute renal failure that have been described in the literature were not statistically significant in this study. These findings suggest that EAV is a more nephrotoxic procedure than renal angiography without EAV.