Carboxypeptidase G2 rescue in delayed methotrexate elimination in renal failure

We report here the case of a 68-year-old woman who presented severe renal failure following the first cycle of high dose methotrexate (HDMTX) for the treatment of a cerebral malignant lymphoma. Before HDMTX administration, serum creatinine value was normal and three days after HDMTX, it reached 457 micromol/L. Leucovorin rescue, hemodialysis and cholestyramine did not increase MTX clearance. Because of the persistence of renal failure, and the high risk of important hematological side-effects associated with high MTX plasma levels, the patient received carboxypeptidase G2 (CPDG2). This allowed MTX plasma levels to decrease by 80% in 15 minutes. No side effects were observed and renal function normalized rapidly. In some patients, when high-dose leucovorin associated with hemodialysis and cholestyramine are unable to restore normal MTX clearance, CPDG2 should be considered because it may represent a safe and efficient alternative for the management of MTX intoxication.

Postsealing genetic variation and population structure of two species of fur seal (Arctocephalus gazella and A. tropicalis)

Commercial sealing in the 18th and 19th centuries had a major impact on the Antarctic and subantarctic fur seal populations (Arctocephalus gazella and A. tropicalis) in the Southern Ocean. The intensive and unrestricted nature of the industry ensured substantial reductions in population sizes and resulted in both species becoming locally extinct at some sites. However, both species are continuing to recover, through the recolonization of islands across their former range and increasing population size. This study investigated the extent and pattern of genetic variation in each species to examine the hypothesis that higher levels of historic sealing in A. gazella have resulted in a greater loss of genetic variability and population structure compared with A. tropicalis. A 316-bp section of the mitochondrial control region was sequenced and revealed nucleotide diversities of 3.2% and 4.8% for A. gazella and A. tropicalis, respectively. There was no geographical distribution of lineages observed within either species, although the respective PhiST values of 0.074 and 0.19 were significantly greater than zero. These data indicate low levels of population structure in A. gazella and relatively high levels in A. tropicalis. Additional samples screened with restriction endonucleases were incorporated, and the distribution of restriction fragment length polymorphism (RFLP) and sequence haplotypes were examined to identify the main source populations of newly recolonized islands. For A. tropicalis, the data suggest that Macquarie Island and Iles Crozet were probably recolonized by females from Marion Island, and to a lesser extent Ile Amsterdam. Although there was less population structure within A. gazella, there were two geographical regions identified: a western region containing the populations of South Georgia and Bouvetoya, which were the probable sources for populations at Marion, the South Shetland and Heard Islands; and an eastern region containing the panmictic populations of Iles Kerguelen and Macquarie Island. The latter region may be a result of a pronounced founder effect, or represent a remnant population that survived sealing at Iles Kerguelen.

MR and CT findings in a case of hibernoma of the thigh extending into the pelvis

Review of the literature shows no report of hibernoma of the thigh extending into the pelvis. Herein we report a case of hibernoma which appeared on CT and MR as a well-defined pelvic mass with contrast enhancement extending through the obturator foramen into the thigh. Fat was demonstrated by CT, whereas MR, using multiplanar sections, better analyzes the extension of the mass. This case demonstrates that hibernoma as liposarcoma can extend through the obturator foramen. However, no definite diagnosis could be made by CT or MR and the tumor must be considered as a "potential" malignant liposarcoma.

Mature cystic teratomas of the ovary: CT and MR findings

OBJECTIVE

To correlate CT and MR patterns of ovarian mature cystic teratomas (MCT).

SUBJECTS AND METHODS

CT and MR findings in 25 histologically proven ovarian MCT were retrospectively reviewed. MCT characterization at CT and MR was based on detection of fat and/or a Rokitansky protuberance. MR signal intensity and CT density numbers of fat were correlated.

RESULTS

At pathology, 24/25 tumors contained fat, 1/25 a water content, and 23/25 a Rokitansky protuberance. Twenty one MCT contained fat with a density number less than-20 HU (mean density: -95 HU) and a signal intensity superior or equal to sub-cutaneous fat on T1 images, however, only six of these had a signal intensity equal to sub-cutaneous fat on T1 and T2 images and 12 had a reversed chemical shift artifact. Three contained fat with a density number ranging from -13 to +8 HU and a signal intensity inferior to subcutaneous fat on T1 images. CT showed a Rokitansky protuberance in 21/23, containing adipose tissue in 16 and calcified structures in 21. Standard MR showed a Rokitansky protuberance in 14/23 and characterized adipose tissue in eight cases, and calcified material in six cases. Finally, CT characterized 24/25 (96%) MCT. Standard MR characterized 22/25 (88%) MCT, and standard MR with fat-suppression sequences characterized 23/25 (92%) MCT.

CONCLUSION

Standard MR is less effective than CT in characterizing fat and has the same difficulty as CT in characterizing fat mixed with hair when its density is high. When fat cannot be identified by either technique, diagnosis of a Rokitansky protuberance is more easily made at CT than at MR.

CT in adnexal torsion with emphasis on tubal findings: correlation with US

OBJECTIVE

Our goal was to determine the CT and US aspects of the fallopian tube in adnexal torsion.

MATERIALS AND METHODS

The CT scans and US studies of 10 patients with surgically proven unilateral torsion of the adnexa were reviewed.

RESULTS

On CT the fallopian tube on the involved side was identified in eight cases as an almost tubular or comma-shaped structure extending from the uterine cornua and covering partially the adnexal mass. This tube was significantly thickened and measured 20-40 mm. Hemorrhage (density > or = 50 HU on precontrast CT scans) was present in the tube in six patients. A heterogeneous contrast agent uptake was detected in the tube in five patients. An adnexal mass was visualized on the involved side in all patients, with hemorrhage in the mass in four patients. Peritoneal fluid and/or ileus were present in six patients. On US an echogenic structure that corresponded to the enlarged tube visualized on CT was detected in three cases and an adnexal mass in all cases.

CONCLUSION

Thickening of the fallopian tube with hemorrhage could be detected by CT and is suggestive of torsion especially if associated with an adnexal mass.

Fat suppression techniques in MR imaging of mature ovarian teratomas: comparison with CT

OBJECTIVE

The aim of this study is to analyze the ability of MR fat suppression techniques to characterize fat components of ovarian mature cystic teratomas (MCT) shown by CT.

SUBJECTS AND METHODS

MR images of eight MCTs of the ovary were obtained using standard sequences followed by a SPIR (spectral presaturation with inversion recovery) sequence in six cases and by Dixon sequences in two cases. In all cases correlation with CT and pathologic findings was achieved.

RESULTS

MR fat suppression sequences showed to be as accurate as CT in detecting fat inside the cystic part of the teratomas (8/8).

CONCLUSION

MR fat suppression sequences should be performed when presence of fat is suspected on images of ovarian tumors produced by standard MR sequences.

Aortic anastomotic pseudoaneurysms: US, CT, MR, and angiography

Correlation of imaging and anatomic findings in seven men with abdominal aortic graft prostheses (four "end-to-end" anastomoses and three "end-to-side" anastomoses) was done to compare the value of different imaging modalities in detecting postoperative complications, especially aortic anastomotic pseudoaneurysms (AAPs). In all cases, angiographic and CT studies were carried out. In six patients ultrasound and MR examinations were also performed. Anatomic verification was obtained by surgery in six patients and autopsy in one case. Five patients had an AAP (four at surgery and one at autopsy), one had a true abdominal aortic aneurysm above the anastomosis, and one a nondetectable abnormality of the aortic suture line. Digital subtraction angiography diagnosed one of five AAPs, missed the true aneurysm in the sixth patient, and was normal in the patient without any aneurysm. Computed tomography correctly diagnosed the five AAPs and the true aneurysm and was normal in the last patient. Ultrasound correctly diagnosed the AAPs in three of four patients, incorrectly diagnosed an AAP in the patient who had the true aneurysm, and was normal in the patient without any aneurysm. Magnetic resonance diagnosed four of four AAPs and the true aneurysm and was normal in the last patient. Computed tomography seems to be the best imaging modality with which to diagnose and evaluate an aortic AAP in patients with aortoiliofemoral graft prosthesis.

Epithelial tumors of the ovary: CT findings and correlation with US

One hundred thirty patients with 170 epithelial ovarian tumors were prospectively studied with computed tomography (CT) before surgery. Ultrasound (US) was performed in 108 patients with 138 tumors. At pathologic examination, 78 tumors (46%) were benign, 14 (8%) borderline, and 78 (46%) malignant. CT results were compared with surgical and pathologic findings in all patients. CT enabled detection of 148 of 170 tumors (87%), and US enabled detection of 118 of 138 tumors (86%). Benign serous cystadenomas (n = 42) were correctly characterized with a sensitivity of 69% at CT and 70% at US. Benign mucinous cystadenomas (n = 21) were correctly characterized with a sensitivity of 62% at CT and 50% at US. Malignancy was suggested in nine of 14 patients (64%) with borderline tumors at CT and in five of 14 (36%) at US. The overall accuracy of characterization of benign versus malignant tumors (including borderline tumors) was 94% with CT and 80% with US. In the 108 patients studied with both CT and US, the sensitivity of CT was significantly superior to that of US (P less than .03), whereas there was no significant difference in specificity (P = .125).

[Comparative study of MRI and x-ray computed tomography in the preoperative evaluation of rectal carcinoma]

Twenty-one patients with middle and low rectal carcinomas have been operated by abdominoperineal resection (APR) in 11 patients, and low anterior resection (LAR) with coloanal anastomosis in 7 and colorectal anastomosis in 3. The distance of the lower margin of the tumor to insertion of the levator ani on the rectal wall was correctly evaluated by CT in 15 of 21 cases (71%) and by MR in 14 of 21 (67%) while digital examination correctly assessed the distance in 17 of 21 (81%). CT and MR were unable to assess extension through the rectal wall. No significant discordance was observed between CT and MR in assessing extension to the perivesical fat, adjacent organs, pelvic side wall or lymphnodes. According to the TNM classification, MR correctly staged 76% (16 of 21) of patients while CT correctly staged 71% (15 of 21).

[MRI of the normal portal system: the artefacts. Apropos of 45 cases]

The protal system of 45 normal patients have been retrospectively studied on spin echo MRI sequences (interleaved cuts): multiple artifacts have been evaluated and 24% of them were visualized at the portal system level. Thus, partial volume effect responsible for almost 25% of the artifacts is not always easily seen on a single sequence. Respiratory and aortic artifacts can deteriorate the visualization of the vascular lumen but cannot be confused with a thrombosis. Well-known artifacts, as slice entry phenomenon and even echo rephasing, represent more than 60% of the artifacts: they are readily recognized when they are typical and indicate flowing blood. On the contrary, an other artifact, representing less than 5% of the total and seen at the level of the left portal vein, simulates a thrombus, on T2 weighed images. We conclude that the frequency and polymorphism of the artifacts are limiting factors of MRI value in the diagnosis of portal vein thrombosis.

Comparison of magnetic resonance imaging and computed tomography in the preoperative staging of rectal cancer

Nineteen patients with middle and lower rectal carcinomas were operated on, with abdominoperineal resection in 10 patients, lower anterior resection with coloanal anastomosis in 6 patients, and colorectal anastomosis in 3 patients. The distance of the lower margin of the tumor to insertion of the levator ani on the rectal wall was correctly evaluated by computed tomography in 12 (63%) of 19 patients and by magnetic resonance imaging in 13 (68%) of 19 patients, while digital examination correctly assessed the distance in 15 (79%) of 19 patients. Computed tomography and magnetic resonance imaging were unable to assess extension through the rectal wall. No significant difference was observed between computed tomography and magnetic resonance imaging in assessing extension to the perivesical fat, adjacent organs, pelvic side wall, or lymph nodes. According to the TNM classification, magnetic resonance imaging correctly staged 74% (14/19) of carcinomas, while computed tomography correctly staged 68% (13/19).

[False image of portal thrombosis in MRI: pitfalls in portal hypertension. Apropos of Budd-Chiari syndrome]

This observation illustrates how difficult it is to interpret the intravascular signal observed with MRI in cases of portal hypertension. A signal occupying the entire lumen of the portal trunk and branches can be seen, which is constantly observed in the axial as well as coronal planes in the 3 series studied. It is hypointense relative to the liver on T1-weighted images, hyperintense on T2-weighted images: this appearance therefore perfectly mimicks portal thrombosis. Ultrasound combined with pulsed Doppler demonstrates the stagnant blood within the patent portal system. This kind of artifact, which is produced by a very slow flow or even by the standstill of flow, is much more difficult to recognize than the common flow artifacts; the criteria put forward by various authors to distinguish between artifacts and thrombosis are of no avail in this case. Examinations must able to confirm or rule out portal thrombosis in the case of portal hypertension with deceleration of flow. In practice, ultrasound studies, combined with pulsed Doppler in the best cases, is therefore indicated as a first-intension technique.

Magnetic resonance imaging of pseudomyxoma peritonei

MRI findings in three cases of pseudomyxoma peritonei, in two cases associated with visceral invasion, are described. MR imaging using the same morphologic criteria as described in ultrasonography and CT suggested the diagnosis in all three cases. In T 1 weighted images (SE 400/28 ms) the hypointensity of signals of both implants and mucoid ascites was found to approach that of muscle tissue. In T 2 weighted images (SE 1600/40, 80, 120 ms), however, there was general hyperintensity of signals, which was more pronounced in mucoid ascites than in implants, and which approached signal intensities of water. Invasion of the viscera was very well depicted in all cases.

[Contribution of MRI in the staging of cancer of the bladder. Apropos of 40 cases]

56 patients with bladder carcinoma were examined by magnetic resonance in the pre-operative staging. In 40 patients where total cystectomy with enterocystoplasty and pelvic node dissection were performed, a good correlation with surgical and pathologic findings was obtained. MR examination using T1 (TR 400 ms, TE 28 ms) and T2 (TR 1,200-1,600 ms, TE 40 80 120 ms) weighted images in different planes where performed after biopsy of the bladder tumor through endoscopy and within 1 or 2 weeks before surgery. Neoplasms were characterized by site, size and growth pattern. Extension through the deep muscle of the bladder wall was correctly identified in 95% with a sensitivity of 95% and a specificity of 95%. Extension through perivesical fat was assessed accurately in 85% with a sensitivity of 66% and a specificity of 100%. Accuracy in evaluating invasion of adjacent organs was 85%, sensitivity 44%, specificity 96%. Lymphadenopathy has been accurately assessed in 97.5% with a sensitivity of 83% and a specificity of 100%. MR correctly staged the tumor according to TNM classification in 24/40 (60%) patients, overestimated the extension in 3/40 (7.5%) and underestimated the extension in 13/40 (32.5%).

MR staging of bladder carcinoma: correlation with pathologic findings

Forty patients with bladder carcinoma were examined preoperatively by means of magnetic resonance (MR) imaging. In all patients, total cystectomy with enterocystoplasty and pelvic node dissection was performed. The surgical and pathologic findings were correlated with the MR findings. Extension through the deep muscle of the bladder wall was present in 20 of the 40 patients and was diagnosed with a sensitivity of 95% and a specificity of 95%. Extension to perivesical fat was present in 18 of 40 patients and was diagnosed with a sensitivity of 66% and a specificity of 100%. Invasion of the adjacent organs was present in nine of 40 patients and was diagnosed with a sensitivity of 44% and a specificity of 96%. On the basis of the MR findings, the tumor was correctly staged, according to the TNM classification, in 24 of 40 (60%) patients, tumor extension was overestimated in three of 40 (7.5%) patients, and tumor extension was underestimated in 13 of 40 (32.5%) patients. MR imaging has been shown to be accurate in identification of macroscopic lymph node involvement and deep muscle involvement. It appears to be at least as useful as computed tomography (CT) in the evaluation of perivesical fat involvement and to be superior to CT in the detection of invasion of adjacent organs. One limitation of MR imaging is in the evaluation of tumor extension into the periurethral glands.

Hepatic vein involvement in hepatocellular carcinoma

A retrospective review of the dynamic computed tomography (CT) and ultrasound scans from examinations of 134 patients with hepatocellular carcinoma was undertaken with emphasis on evaluation of hepatic vein involvement. Hepatic veins were involved in 8 patients (5.9%). Portal vein obstruction was associated in 7 of these cases. Sonography demonstrated hepatic vein involvement in 6 cases was considered within normal limits in 1 and failed to display hepatic veins in another. Dynamic CT was superior in depicting venous obstruction in all the cases by different signs including (a) hypodensity and enlargement of the vessel, (b) perivenous arterial hypervascularization surrounding the hypodense intraluminal region, and (c) hemokinetic changes in relation to the outflow obstruction. The frequency and significance of these CT signs are discussed and correlated in 2 patients with magnetic resonance imaging (MRI) data.

[Magnetic resonance imaging of cancer of the rectum]

MRI (Magnetic Resonance Imaging) has become a major diagnostic method, in many fields. Its results, in the pre-operative evaluation of rectal cancers, are presented here. The possibilities of determining by MRI, parietal extension, peri-rectal fat invasion, extension to adjoining organs and nodes, are specified. Then, the contribution of MRI to the measurement of the distance between the lower pole of the tumor and the levator muscles plane, is evaluated.

[Castleman's disease. X-ray computed tomographic aspect. Apropos of 2 mediastinal forms and a multicentric form]

A multicentric form of Castleman's disease is described, this being a rare affection for which CT image characteristics have not, to our knowledge, been reported. Two cases of localized and one case of multicentric Castleman's disease are reported, and differential characters of these two forms with common histology: angio-follicular lymphoid hyperplasia, outlined. The localized form is found mainly in the mediastinum in young patients and follows a favorable course with recovery after exeresis. The diffuse form develops in later life and presents with severe systemic signs and a marked biological inflammatory syndrome Glands and viscera are affected and its course is grave, with mostly fatal relapses. Angiography suggests diagnosis when images show hypervascular lesions in lymph glands. CT scan imaging with contrast is very suggestive when glandular lesions are present that take up contrast strongly. This appearance should always raise the possibility of Castleman's disease.

Preoperative assessment of the extension of rectal carcinoma: correlation of MR, surgical, and histopathologic findings

Nineteen patients with rectal carcinoma were evaluated prospectively. The extent of tumor and the relationship of the tumor to the levator ani muscle were studied as this determines the choice of the surgical procedure (abdominoperineal resection versus low anterior resection). Peroperative assessment and detailed evaluation of the pathologic specimens were correlated with magnetic resonance (MR) features. Magnetic resonance staging and surgical findings were at variance in four of 15 cases (27%). Magnetic resonance had sensitivities and specificities of 75 and 100% in the detection of perirectal growth. Magnetic resonance demonstrated invasion of adjacent pelvic side wall and sacrum in two of two cases. The comparison with TNM classification demonstrated that MR correctly staged 15 of 19 cases (79%). This study shows that MR is a good examination to evaluate the involvement of perirectal fatty tissues and adjacent structures. The low prevalence of involved lymph nodes in our cases prevents significant positive predictive values. Nevertheless, MR can help to select patients for local excision or for preoperative radiotherapy.

[Magnetic resonance imaging of the pelvis. Methodological aspects]

Multiparametric choice is needed in Magnetic Resonance Imaging (MRI). In addition to matrix definition, section thickness, accumulation number, the repetition time TR, the echo time TE (for the spin echo technique) and the plane selection are of great importance. In pelvic examination, information supplied by T1 and by T2 weighted images is complementary. So, comparison between the three dimensional sections is of great interest. Although long acquisition times could, in theory, provide better images and therefore more clinical information, the patient comfort must be considered in choosing a reasonable examination time. We believe that it is possible, without great loss of information, not to make inversion recovery sequences. Using a 0.5 T superconducting magnet, sequences were done with TR of 1,200 ms for T2 weighted images and two echoes with TE of 40 or 50 ms. Twice repeated sequences (for averaging purpose) and 256(2) matrix (with a 42 cm field diameter) seem to be well adapted to MRI clinical applications.

[Magnetic resonance imaging of the pelvic area. Preliminary results]

Magnetic Resonance Imaging (MRI) is chiefly characterized by its natural contrast and by its capability of producing images in the three spatial directions. Although nearly all pathological tumors have prolonged T1 and T2 relaxation times and therefore it seems to be difficult to distinguish them one from another, significant pathological particularities can be obtained by comparing T1 and T2 weighted images. MRI is of particular interest to provide morphologic data and to demonstrate the relationship of tumors to vascular axes. Furthermore information in three dimensions (scans along transaxial, sagittal and coronal planes) is compared to produce a detailed morphological analysis of the tumor and of the adjacent structures. 0,5 T imaging was performed in 25 patients with pathologic pelvis and in 5 normal volunteers.