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Biomedical subjects

C D Johnson

Publications and source records attributed to C D Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1995

Distinction between cavernous hemangiomas of the liver and hepatic metastases on CT: value of contrast enhancement patterns.

OBJECTIVE: Differentiating between cavernous hemangiomas of the liver and hepatic metastases on the basis of single-pass, contrast-enhanced CT is a significant and frequently encountered diagnostic challenge. Recognition of characteristic enhancement features of cavernous hemangiomas can aid in effectively distinguishing between these lesions. The purpose of this study was to determine sensitivity and specificity of dense, globular enhancement for differentiating cavernos hemangiomas and metastases during single-pass, contrast-enhanced CT. MATERIALS AND METHODS: CT appearance of 133 lesions in 91 patients with cavernous hemangiomas (44 patients) or metastases (47 patients) was retrospectively evaluated in a blinded review. CT examinations were performed with nonhelical technique following injection of 150 ml of contrast material. All patients with metastases had pathologic proof (n = 47). Patients with cavernous hemangiomas were clinically stable for at least 2 years after CT (n = 43) or had tissue proof (n = 1). All lesions were evaluated based on the following criteria: (1) Type of enhancement: globular, linear, diffuse and homogeneous, or diffuse and heterogeneous. (Globular enhancement was considered to be present when enhancing nodules less than 1 cm in diameter were seen within lesions.) (2) Continuity of enhancing tissue: continuous or noncontinuous. (Uninterrupted collections of contrast material within at least 50% of a lesion were considered continuous. Multiple, separate collections of contrast material were considered noncontinuous.) (3) Degree of enhancement: hypo-, iso-, or hyperdense relative to the aorta. (4) Distribution of enhancement: peripheral, central, or mixed. RESULTS: Seventy-six percent of cavernous hemangiomas had globular enhancement, compared to 10% of metastases (p < .001). Seventy-two percent of cavernous hemangiomas had enhancement isodense with the aorta, and 96% of metastases were hypodense (p < .001). Sixty-seven percent of cavernous hemangiomas had peripheral enhancement, compared to 38% of metastases (p < .001). The combined finding of globular, isodense enhancement was seen in 67% of cavernous hemangiomas and none of the metastases. Only 10% of cavernous hemangiomas had nonglobular, hypodense enhancement, compared with 90% of metastases. Combining all criteria, reviewers correctly classified 122 (92%) of the lesions. Presence of globular enhancement, isodense with the aorta, was 67% sensitive and 100% specific in differentiating cavernous hemangiomas from hepatic metastases. CONCLUSION: In most cases, differentiation of cavernous hemangiomas from hepatic metastases can confidently be made with single-pass, contrast-enhanced CT. Globular enhancement, isodense with the aorta, is 67% sensitive and 100% specific in differentiating cavernous hemangiomas and hepatic metastases.

Adult↗
PubMed1995

Fibrolamellar hepatocellular carcinoma: stage at presentation and results of aggressive surgical management.

OBJECTIVE: The purpose of this study was to report the stage of fibrolamellar carcinoma at presentation and the imaging findings of postoperative recurrent tumor in an aggressively managed population and to assess the implications of those findings relative to the patients' management. MATERIALS AND METHODS: Imaging studies in 10 patients with pathologically proved fibrolamellar carcinoma were reviewed. Preoperative studies included CT (n = 10), sonography (n = 8), and MR imaging (n = 2). Postoperative studies included CT (n = 9), sonography (n = 4), and MR imaging (n = 1). Imaging findings were correlated with clinical and surgical follow-up data. Patients were followed up for 2-75 months (median, 26 months). RESULTS: At presentation, seven (70%) of 10 patients had metastatic lymphadenopathy. Seven patients (70%), including four with lymph node metastasis, had tumor resections with intent to cure. Postoperative imaging studies revealed recurrent tumor in all seven of these patients, including six patients (86%) who had intrahepatic recurrence with or without lymph node metastasis after 6-18 months, and one patient (14%) who had distant metastases 66 months postoperatively. Recurrent lesions were subsequently resected in three (43%) of seven patients, who were disease-free at a mean of 8 months after their second resection. Five patients died after 9 months mean survival, and two patients were alive with residual tumor after 3 months mean follow-up. CONCLUSION: Fibrolamellar carcinomas are often of advanced stage at diagnosis. Recurrence after resection with intent to cure is common. Early and frequent follow-up imaging is necessary for optimizing surgical management in patients with fibrolamellar carcinoma.

Adolescent↗
PubMed1995

Gadoteridol-enhanced MR imaging of malignant hepatic tumors: effects of triple versus standard doses on lesion-liver contrast.

OBJECTIVE: The purpose of this study was to compare liver signal-to-noise ratio (SNR), lesion SNR, and lesion-liver contrast-to-noise-ratio (CNR) in patients with malignant liver lesions after the administration of a standard dose (0.1 mmol/kg of body weight) or a triple dose (0.3 mmol/kg) of a gadolinium chelate (gadoteridol). We hypothesized that the higher dose would produce a higher lesion-liver CNR and therefore increase the conspicuity of hepatic lesions. MATERIALS AND METHODS: A total of 85 patients with malignant hepatic masses (61 metastases, 22 hepatocellular carcinomas, and two lymphomas) proved by histologic or follow-up studies underwent MR imaging at 1.5 T. T1-weighted spin-echo imaging and gradient-echo imaging were done before and within 1 min after (gradient echo) as well as 5 (spin echo) and 15 (spin echo) min after the injection of 0.1 or 0.3 mmol of gadoteridol per kg, randomized before the start of the study (39 patients received the standard dose, and 46 received the triple dose). The signal intensities of the liver and lesions and the SD of background noise were measured by use of regions of interest to calculate the SNR of the liver and malignant lesions and the lesion-liver CNR. RESULTS: The lesion-liver CNR was increased significantly at 5 and 15 min after the administration of gadoteridol. No significant differences in the liver SNR, lesion SNR, and lesion-liver CNR (after 1 min: standard dose, -5 +/- 8, and triple dose, -4 +/- 14; after 5 min: standard dose, -1 +/- 5, and triple dose, 2 +/- 8; and after 15 min: standard dose, 1 +/- 5, and triple dose, 6 +/- 20) were found between the doses at all time points. CONCLUSION: Triple-dose gadoteridol does not improve the lesion-liver contrast of malignant hepatic lesions over that provided by the standard dose and is not warranted for liver MR imaging.

Adult↗
PubMed1995

Single-pass CT of hepatic tumors: value of globular enhancement in distinguishing hemangiomas from hypervascular metastases.

OBJECTIVE: The purpose of this study was to evaluate the sensitivity and specificity of globular enhancement for differentiating hepatic hemangiomas from hypervascular metastases on single-pass, contrast-enhanced CT scans. Globular enhancement was defined as enhancing nodules less than 1 cm seen within a lesion. MATERIALS AND METHODS: Fifty CT examinations were retrospectively evaluated in a blinded fashion by two independent reviewers. The CT studies were done with nonhelical technique after the IV injection of 150 ml of contrast material. The series included 25 patients with histologically proven hypervascular hepatic metastases (carcinoid, islet cell carcinoma, and leiomyosarcoma) and 25 patients with clinically proven hepatic hemangiomas. Patients with hemangiomas were clinically stable for at least 2 years after the CT studies. A single lesion was isolated from the first-pass, contrast-enhanced portion of each examination; the remainder of the examination was excluded from the review to minimize reviewer bias. Each lesion was evaluated for (1) the presence or absence of globular enhancement (defined as enhancing nodules less than 1 cm seen within a lesion), (2) the density of globular enhancement relative to that of the aorta, (3) the degree of border definition (well or poorly marginated), and (4) the presence or absence of a hypodense halo. A diagnostic impression was then recorded for each lesion. RESULTS: Globular enhancement was 88% sensitive and 84-100% specific for differentiating hepatic hemangiomas from hypervascular metastases (p < .001). A mean of 62% of hemangiomas showed globular enhancement isodense relative to that of the aorta; none of the metastases showed globular, isodense enhancement. The majority of the metastases showed nonglobular enhancement (mean, 92%). The reviewers showed 84% agreement in the identification of (1) globular enhancement in hemangiomas, (2) lack of globular enhancement in metastases, and (3) globular enhancement in the combined set of all lesions. Neither the presence of a hypodense halo nor the degree of border definition was significant in distinguishing between the two groups of lesions. The reviewers showed 96% agreement in the categorization of metastases and 76% agreement in the categorization of hemangiomas. There was 86% agreement in the categorization of all lesions. Overall, reviewers diagnosed a mean of 89% of lesions correctly. A mean of 98% of metastases and a mean of 80% of hemangiomas were diagnosed correctly. CONCLUSIONS: Globular enhancement is highly sensitive (88%) and specific (84-100%) for differentiating hepatic hemangiomas from hypervascular metastases on single-pass, contrast-enhanced CT scans.

Adult↗
PubMed1995

Two-layer repair of the transversalis fascia is sufficient for inguinal hernia repair.

The Shouldice four-layer repair is considered to be the gold standard procedure for repair of inguinal hernia with low recurrence rates around 1%. Tension-free two-layer repair of the transversalis fascia may be all that is required to avoid recurrence. We compared the early recurrence rate after two-layer repair of the transversalis fascia or the standard four-layer Shouldice technique in a randomised study of elective inguinal herniorrhaphy. In 48 patients (53 repairs) who had a two-layer transversalis fascia repair, there was one recurrence (2%) in the first 12 months after operation, though there was one more recurrence within 36 months (total 4%). In 39 patients who had a four-layer Shouldice repair (42 repairs), there was no recurrence at 12 months but at 36 months two recurrences (5%) were found. We conclude that a two-layer repair of the transversalis fascia is anatomically correct, physiologically sound and can provide equivalent results to the standard Shouldice repair for inguinal hernia.

Adult↗
PubMed1995

Management of ductal carcinoma in situ of the breast.

The advent of mammographic breast screening has increased the detection of ductal carcinoma in situ (DCIS), which now accounts for 15-20% of all breast cancer. While symptomatic DCIS has been treated satisfactorily by mastectomy, this may be an overtreatment of smaller screen-detected lesions. Although local excision, with or without radiotherapy, is associated with a significant risk of local recurrence of DCIS or invasive cancer, salvage surgery is usually successful. The long-term breast-specific mortality rate of treatment by mastectomy and local excision are similar. Whereas mastectomy is still appropriate for women with lesions > 30 mm in diameter or centrally placed and for those women who demand the best possible disease-free survival, local surgery should otherwise be considered.

Breast Neoplasms↗
PubMed1995

Pyogenic hepatic abscess after pancreatic resection for chronic pancreatitis.

Seventeen patients underwent surgery for alcohol-induced chronic pancreatitis. Three patients later presented with pyogenic liver abscess. The time interval between surgery and presentation with hepatic abscess varied from 6 weeks to 3.5 years. All patients were diabetic, the presentation was insidious and all made an uneventful recovery, two with percutaneous drainage and one with antibiotics alone. The aetiology of this uncommon complication is discussed.

Adult↗
PubMed1995

Extended lymph node dissection (D2 resection) should now be performed routinely in the curative surgical treatment of gastric carcinoma.

Gastric cancer has a dismal prognosis in the Western world. In contrast, in Japan where extended lymphadenectomy is the rule in curative gastric cancer surgery, the prognosis is much better. The arguments for and against the adoption of this procedure in the West are presented. This procedure is safe in the hands of experienced surgeons and by improving locoregional control, may improve survival. However, in the absence of controlled data supporting a survival advantage, the excess morbidity and mortality of this extended procedure in the West may not be justified.

Humans↗
PubMed1994

Sympathetic activity recorded from the rat caudal ventral artery in vivo.

1. In twenty-five sodium pentobarbitone (alpha-chloralose supplemented)-anaesthetized, artificially ventilated and paralysed rats, postganglionic sympathetic single unit activity was recorded at the level of the adventitia of the caudal ventral artery of the tail using a focal recording technique. 2. Ten units were identified as being sympathetic in nature, as they were activated following electrical stimulation of the lumbar sympathetic chain. The on-going activity of seven of these was blocked by hexamethonium (6-12 mg kg-1). 3. The units were not under tonic baroreceptor modulation, as indicated by the lack of pulse modulation of discharge. Respiratory modulation was apparent, with neurones firing mainly during expiration (phrenic silence), and activity was influenced also by the lung inflation cycle. Whole-body warming decreased unit activity. 4. Interspike interval and autocorrelation analysis showed that unit discharge was dominated by the respiratory rhythm and that units tended to discharge in bursts (often duplets). It is suggested that the intraburst interval may be determined by a hypothetical sympathetic oscillator. 5. This study presents the first analysis of single unit activity recorded in vivo from sympathetic fibres innervating an identified blood vessel.

Animals↗
PubMed1994

Inflammation impairs neurally mediated responses to electrical field stimulation in isolated strips of human gallbladder muscle.

Strips from human gallbladder removed at surgery were exposed to cholecystokinin octopeptide CCK-OP 15 nM and were subjected to electrical field stimulation (EFS) in vitro using parameters for selective stimulation of nerves (5- to 10-sec trains of 0.3-msec pulses at 10 Hz). An adjacent strip from the same specimen was processed for histological examination. These preparations were given a numerical score for inflammatory change. The strength of contraction in response to CCK-OP was inversely related to the severity of inflammation. Gallbladders with no response to EFS had a higher inflammation score (median 11, range 5-16) than those with a response (median 7, range 3-12). We conclude that inflammatory changes in human gallbladder impair responses to neural and hormonal stimulation, but we are unable to determine unequivocally in this study whether this is a result of damage to nerves or muscle cells. However, the observation that some strips were able to contract in response to CCK-OP but not to neural stimulation suggests the possibility of neural damage in gallbladder inflammation.

Cholecystitis↗