Atrial linear lesions: feasibility using cryoablation

BACKGROUND

Long linear lesions are created in the left atrium to modify the atrial substrate, thereby curing atrial fibrillation. The creation of long linear left atrial lesions using radiofrequency (RF) ablation is time consuming and difficult. Furthermore, it might result in significant complications. Cryoablation might overcome some of the disadvantages of RF ablation. Therefore, the aim of our study was to assess whether the creation of a long linear lesion is possible using cryotherapy.

METHODS

A right atrial septal linear lesion was created in six pigs (median weight: 50 kg; range: 40-60 kg). The ablation procedure was performed with a 7-F Freezor cryocatheter. The nonfluoroscopic mapping system LocaLisa was used as a navigation tool. At each point, freezing was maintained at the lowest attainable temperature (-75 degrees C) for 4 minutes. The CARTO system was used for the evaluation of the linear lesions. Furthermore, all animals were sacrificed immediately after the ablation procedure and a postmortem examination of the lesions was performed. Additionally, an analysis of the amplitudes of the intracardiac electrograms registered via the ablation catheter was performed before and after the ablation procedure.

RESULTS

A right atrial septal linear lesion could be created successfully in all six pigs. For the performance of this ablation line, a median number of 16 cryoapplications (range, 11-26) was necessary. The amplitudes of the intracardiac electrograms registered via the ablation catheter decreased significantly after ablation. The CARTO bipolar voltage map revealed very low potentials along the ablation line and showed a sharply demarcated ablation area at the septum in all pigs. Further analysis of the CARTO map revealed an incomplete conduction block in all cases. Most of the pigs had a small gap close to the fossa ovalis. The postmortem examination of 2,3,5-triphenyl-tetrazolium chloride-stained specimens showed sharply demarcated lesions without any ulcerations. There were no major complications during the procedure.

CONCLUSIONS

The creation of long linear lesions using cryoablation is feasible and safe. Lesion characteristics are different and more favorable than those created by RF. However, the aim of creating a transmural lesion and a complete conduction block remains an unsolved problem even with current cryoablation techniques. Nevertheless, growing experience and technical improvements might overcome some of the current limitations of this new technique.

Use of a hanging-weight system for isolated renal artery occlusion during ischemic preconditioning in mice

Renal failure from ischemia contributes to morbidity and mortality. Ischemic preconditioning (IP) represents a powerful strategy for kidney protection, and recent advances in transgenic mice may help elucidate its molecular mechanisms. However, murine IP is technically challenging and experimental details significantly influence results. Thus we developed a novel model for renal IP using a hanging-weight system for isolated renal artery occlusion. In contrast to previous models, this technique eliminates the need for clamping the vascular pedicle (artery/vein). In fact, assessment of renal injury after different time periods of ischemia (10-60 min) revealed highly reproducible increases in plasma creatinine and potassium levels, while creatinine clearance, urinary flow and potassium/sodium excretion were significantly attenuated. Using different numbers of IP cycles, we found maximal protection with four cycles of 4 min of ischemia-reperfusion. In contrast, no significant renal protection was observed with IP of the vascular pedicle. To assess transcriptional responses in this model, we isolated RNA from preconditioned kidneys and found time-dependent induction of erythropoietin mRNA and plasma levels with IP. Taken together, this model provides highly reproducible renal injury and protection by IP, thus minimizing variability associated with previous techniques based on clamping of the renal pedicle. Further studies on renal ischemia/IP in mice may consider this technique.

Choroid plexus tumors differ from metastatic carcinomas by expression of the excitatory amino acid transporter-1

Tumors of the choroid plexus (CPTs) are rare neoplasms of neuroectodermal origin usually arising in pediatric patients. However, CPT may occur at any age, and their distinction from metastatic carcinomas is often difficult in adult cases. Because CPTs frequently show focal glial differentiation, we now investigated 35 CPTs (19 males and 16 females 0.3-70 years old; median age, 25.0 years), including 21 choroid plexus papillomas (CPPs), 5 atypical CPP, and 9 choroid plexus carcinomas regarding their expression of the excitatory amino acid transporter-1 (EAAT1, corresponding to rodent GLAST/GLAST-1) by immunohistochemistry. In addition, 77 metastatic carcinomas, including 64 adenocarcinomas with mostly papillary formations, derived from different organs were examined. Of the 35 CPTs, 23 (66%) showed membranous EAAT1 expression in variable numbers of tumor cells, including all atypical CPP and 3 of 9 choroid plexus carcinomas (33%). None of the metastatic carcinomas showed membranous immunostaining. Excitatory amino acid transporter-1 expression in CPT was significantly age dependent (P < .0001), with the proportion of EAAT1-positive tumor cells increasing with age, but not sex dependent. There was a highly significant difference between EAAT1 expression in CPT and in metastatic carcinomas (P < .0001). Establishing a cutoff value of 1% immunoreactive tumor cells served in adult cases to distinguish CPT from metastatic adenocarcinomas with 100% specificity and 70% sensitivity and was associated with positive and negative predictive values of 100% and 91%, respectively. Our findings indicate that EAAT1 immunohistochemistry may be useful in differentiating CPT from metastatic carcinomas.

Solitary pulmonary nodules: association between signal characteristics in dynamic contrast enhanced MRI and tumor angiogenesis

PURPOSE

To estimate the association between signal characteristic of dynamic enhanced MRI using curve types and angiogenesis in solitary pulmonary nodules.

MATERIALS AND METHODS

Thirty-six patients with a solitary pulmonary nodule (SPN) ranging in size from 6 to 37 mm (median 17 mm) underwent dynamic contrast enhanced MRI with a time interval of 10 s over a total period of 4 min. Resulting from the time-intensity curves four different enhancement curve profiles (A-D) were defined: type A with strong increase followed by early washout, type B with strong increase without washout, type C with slow increase and type D without relevant increase. Maximum peak (Pmax), slope of the first bolus transit (slope) and washout were calculated. Microvessel densities (MVD) were counted at the margins and at the center of the nodules. The mean MVD of each nodule was calculated. Enhancement characteristics were correlated with MVD grouped by diagnosis and by curve types. Curve types were correlated with the score of vascular endothelial growth factor (VEGF).

RESULTS

The frequency of malignancy was 55% (20/36). Using curve types for differentiation between malignant and benign SPN, the sensitivity, specificity and accuracy were 100%, 75% and 89%, respectively. The correlation between Pmax and MVD(mean) for all nodules was moderate (r(s)=0.4, P=0.02). A relevant correlation was found between Pmax and MVD(margin) in curve type A (r(s)=0.63; P=0.04) and Pmax and MVD(mean) in curve type C (r(s)=0.86; P=0.006). No positive correlation was found between Pmax and MVD (mean, center and margin) in curve type B. No significant correlation was found for slope and washout. VEGF score correlated positively with curve types (r(s)=0.67; P<0.001).

CONCLUSION

A relevant association between perfusion curve profiles and angiogenesis was found in malignant nodules having early washout and in benign lesion with a slow increase of enhancement. In cases of strong signal increase without washout additional factors for enhancement must be considered. The use of curve profiles could allow for the estimation of the extent of VEGF.

Giant mullerian duct cyst with malignant transformation in 15-year-old boy

We present a case of a giant mullerian duct cyst with components of clear cell adenocarcinoma in a 15-year-old boy. Complete tumor resection was achieved in two steps. The presented case with a combination that has never been described before may change the perspective of treatment approaches for this rare entity.

Theophylline Improves Early Allograft Function in Rat Kidney Transplantation

Several previous studies have demonstrated a beneficial effect of the adenosine receptor (AdoR) antagonist theophylline in different forms of acute renal failure in laboratory animals and in humans. Therefore, we wanted to test whether theophylline can also improve impaired allograft function following ischemia reperfusion injury in experimental kidney transplantation (KT). Orthotopic transplantation of the left kidney was performed from Fisher 344 into Lewis rats. All transplanted rats received daily cyclosporine (5 mg/kg). The effect of theophylline treatment (10 mg/kg) on graft function was compared with appropriate controls on day 5 after KT by assessment of glomerular filtration rate (GFR) (inulin clearance). On day 5, GFR of allografts in control rats was 0.23 +/- 0.05 ml/min/g kidney weight (n = 10) compared with 0.50 +/- 0.09 ml/min/g in rats receiving theophylline (n = 9, p < 0.01), representing a 2-fold increase in GFR. Renal AdoR A(1) mRNA content was significantly increased in both KT groups compared with their respective control groups, whereas mRNA of AdoR A(2a), A(2b), and A(3) were found to be unchanged. Theophylline did not affect significantly interstitial infiltration of the graft by monocytes/macrophages and T-cells. Likewise, serum cytokines [interleukin (IL)-2, IL-6, IL-10, tumor necrosis factor-alpha] and erythropoietin plasma levels were not different among the allograft groups. The present study demonstrates that theophylline remarkably improved early renal allograft function in rats undergoing KT without influencing cytokine serum patterns or tissue inflammation. Since theophylline is a commonly used medication in humans, clinical studies in patients undergoing KT are warranted.

Prevention of carotid artery restenosis after sirolimus-coated stent implantation in pigs

BACKGROUND AND PURPOSE

To test the feasibility of self-expanding drug-coated nitinol stents for prevention of restenosis in an animal model. Stent implantation in the carotid artery (CA) has been shown to be feasible for treatment of CA stenosis. Even though the restenosis rate in CA is reported to be lower than in the coronary and peripheral arteries, problems may arise with increasing numbers of treated patients and lengthier follow-up.

METHODS

After predilatation with 8-mm balloons, 8 Goettinger minipigs were randomly selected to receive a sirolimus-eluting self-expanding nitinol stent (7 mm/80 mm) as well as the same stent without sirolimus/polymer coating in the right or left CA. Aspirin was given starting 3 days before the intervention and administered for an additional 4 weeks. Clopidogrel was administered for 10 days.

RESULTS

After 6 weeks, 2 subacute occlusions were observed in both groups. In the remaining vessels, the neointima was significantly reduced by sirolimus/polymer-coated stents (5.9+/-2.5 versus 0.7+/-1.0 mm2).

CONCLUSIONS

Sirolimus self-expanding nitinol stents may be an effective tool in reducing neointimal formation in CA.

Significance of the "halo" sign for progression and regression of nodular pulmonary amyloidosis: radiographic-pathological correlation (2005:6b)

We describe a case of a systemic amyloidosis of kappa-AL type, presenting at CT as focal lung parenchymal nodules or areas of consolidation with or without a halo,showing different sizes and morphologic kinetics at follow-up. Lesions accompanied by a halo revealed faster progression and earlier response to chemotherapy with almost complete resolution after high dose therapy with a cytostatic alkylating agent(Melphalan) and autologous peripheral stem cell transplantation than their counterparts without a halo. Amyloid deposition was histologically confirmed, and severe inflammatory activity was found in and at the margins of the amyloidomas, the latter correlating in CT with the halo sign. In our case, this sign had a high prediction for growth kinetics and response to therapy of pulmonary amyloid.

A complicated case of bilateral cystic nephroma in a 16-month-old boy

We describe a case of a progressive bilateral cystic nephroma (BCN) in a child undergoing a multistaged surgical procedure. After partial resection of the left sided tumor, a progress occurred on that side and the left kidney had to be removed 10 weeks later. After 35 months a tumor progression was observed on the right side together with an ureteral obstruction leading to a decreased renal function. In a third operation a complete tumor resection on the right side was achieved through longitudinal partial nephrectomy, reconstruction of the renal pelvis, and reanastomosis of the reconstructed pelvis and ureter. The patient showed no evidence of the disease at 28 months of follow-up. The presented case provides an evidence that in BCN a tumor progress may occur after multistaged surgical approaches. A single-staged complete tumor resection with renal salvage techniques seems indicated.

Disseminated epitheloid hemangioendothelioma mimicking symptoms of systemic vasculitis

BACKGROUND

Epitheloid hemangioendothelioma is a rare malignant tumor which can involve bones, liver, lungs, kidneys, deep soft tissue, muscles, dermis, and central nervous system. Multifocal disease occurs in 10% of the cases. The clinical presentation results from occlusion of small blood vessels due to the disease itself or as a paraneoplastic syndrome.

CASE REPORT

We present a patient with symptoms suggesting systemic vasculitis (ESR and CRP elevated, weight loss, arthralgia, livedoid rash, and skin ulcerations) who finally was diagnosed having a disseminated epitheloid hemangioendothelioma when PET scan revealed hypermetabolic multifocal skeletal and soft tissue lesions.

DISCUSSION

Diseases mimicking systemic vasculitis and the value of PET in this setting are discussed.

Invasive pulmonary aspergillosis: frequency and meaning of the “hypodense sign” on unenhanced CT

The purpose of this study was to establish the diagnostic value of central hypointensity ("hypodense sign") in lung consolidations or nodules, in severely immunocompromised or neutropenic patients, suspected of having invasive pulmonary aspergillosis (IPA), and to assess its recognition on unenhanced CT scans. Serial CT scans of the lung were retrospectively reviewed in 43 consecutive immunosuppressed patients with IPA, and assessed for the presence of the hypodense sign using standard mediastinal and lung windowing settings, as well as a special, narrower window setting (width 110-140 HU; level 15-40 HU). The temporal relationship between the occurrence of the first CT-finding suspicious of IPA and the appearance of the hypodense sign, as well as between this and the occurrence of the crescent sign, cavitation or reduction in lesion size, was evaluated. Additionally, CT-scans from 89 immunocompromised patients with viral (n=45) or bacterial (n=44) pneumonia, investigated in the same time period at our institution were reviewed, with respect to the presence of the "hypodense" sign. Unenhanced CT scans revealed the hypodense sign in 11 neutropenic patients and 2 severely immunocompromised patients, out of a total of 43 patients with IPA evaluated in this study (30.2%). The mean time between the appearance of the first CT-findings of IPA (large nodule or consolidation +/- positive halo sign) and the hypodense sign was 7.8 days, while the time interval between the hypodense sign and the occurrence of crescent sign, cavitation, or decrease of the lesion's size was 8.3 days. The hypodense sign did not occur in any of the patients with viral or bacterial pneumonia, in the control series. We consider the hypodense sign to be a supplementary tool in the diagnosis of IPA. Its sensitivity was low in our series, but the high specificity makes it valuable in predicting IPA, anticipating the occurrence of cavitation or crescent sign, which are considered specific, but late findings of IPA. The hypodense sign is recognizable also on unenhanced CT, when a narrower lung window setting is used.

Steroid Profile in an Adrenocortical Carcinoma Producing Aldosterone

We report a rare case of primary aldosteronism due to an adrenocortical carcinoma. A 61-year-old woman with a history of hypertension and hypokalemia was referred for evaluation of a 4.2 cm measuring adrenal mass without secondary signs of malignancy. Endocrinological testing was consistent with primary aldosteronism. The patient underwent surgical resection of the adrenal mass; histology revealed an adrenocortical carcinoma. Postoperatively blood pressure, serum potassium, and aldosterone returned to normal. Four months after adrenalectomy, the patient presented again with hypokalemic hypertension and was found to have metastatic disease. Endocrinological investigation revealed primary aldosteronism and subclinical autonomous glucocorticoid hypersecretion. Careful hormonal investigation should be obtained in patients with adrenal masses causing excessive aldosterone secretion. In uncertain cases of primary aldosteronism, we would suggest to measure 18-hydroxycortisol levels, as excessive amounts may indicate adrenocortical carcinoma.

Effect of dopamine D3 receptor blockade on renal function and glomerular size in diabetic rats

Dopamine D2-like receptors, including D2, D3, and D4 receptors, are involved in the regulation of glomerular hyperfiltration due to diabetes mellitus. These hemodynamic alterations represent a risk factor for the later development of diabetic nephropathy. The aim of the present study was to determine whether the D3 receptor subtype modulates the diabetes-induced increase in glomerular filtration rate (GFR) in rats. Renal function was studied in Sprague-Dawley rats 14 days after induction of a moderate diabetes mellitus (DM) by streptozotocin and in non-diabetic controls (CON). Rats were orally treated either with the peripherally acting, selective dopamine D3 receptor antagonist BSF 135170 (BSF, 10 mg/kg per day for 2 weeks) or with vehicle (VHC). Perfusion-fixed kidneys were used for estimation of glomerular volume. In conscious rats, which were treated with BSF, the DM-induced increase in fluid intake, urinary output, and renal sodium excretion was significantly less pronounced than in the vehicle group (DM-VHC). In the clearance experiments, GFR in CON was about 0.84+/-0.04 ml/min per 100 g body weight. The DM-VHC group presented a significant glomerular hyperfiltration (1.09+/-0.04 ml/min per 100 g body weight). Treatment with BSF significantly lowered GFR towards levels of CON. The estimated glomerular volume was 0.73+/-0.03 x 10(6) microm3 in the CON-VHC group and 0.86+/-0.04 x 10(6) microm3 in the DM-VHC animals. Interestingly, treatment with BSF decreased the glomerular volume in both groups. Irrespective of BSF treatment, kidney wet weight related to body weight was about 36% higher in DM animals compared with CON animals. We conclude that dopamine D3 receptors represent a target for the modulation of diabetes-induced glomerular hyperfiltration. Therefore, the results encourage the testing of the possible beneficial effects of long-term D3 receptor blockade on the development of diabetic nephropathy.

Adrenocortical carcinoma producing 11-deoxycorticosterone: a rare cause of mineralocorticoid hypertension

A 37-yr-old man presented with the classic signs of mineralocorticoid excess hypertension and hypokalemia. The cause was not aldosterone excess, but elevation of plasma 11-deoxycorticosterone (DOC). Computed tomography (CT) scans showed a large right adrenal mass without signs of metastatic disease. The tumor was removed by open laparotomy, and histology revealed an adrenocortical carcinoma. Two yr after diagnosis, the patient is in good general condition and there is no sign of recurrence or metastatic disease, despite the large tumor size. DOC producing adrenocortical carcinomas causing mineralocorticoid hypertension are very rare, so far only 10 cases have been described in the literature.

Reliability of differentiating human coronary plaque morphology using contrast-enhanced multislice spiral computed tomography: a comparison with histology

BACKGROUND

Initial clinical results indicate that multislice spiral computed tomography (MDCT) might be useful for the noninvasive characterization of human coronary plaque morphology by determining tissue density within the lesions. This seems to be of clinical relevance, because coronary artery disease might be detected at an early stage before calcifications occur and noncalcified plaques that may be more likely to rupture could also be visualized noninvasively. The aim of the present study was to evaluate the reliability of contrast-enhanced MDCT in differentiating human atherosclerotic coronary plaque morphology by comparing it with the histopathologic gold standard.

METHODS AND RESULTS

Twelve human hearts were scanned postmortem using an MDCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) high-resolution computed tomography scanner to detect atherosclerotic coronary plaques. Density measurements were performed within detected plaque areas. The exact location of each plaque was marked at the surface of the heart to assure accurate histopathologic sectioning of these lesions. The plaques were classified according to a modified Stary classification. Seventeen plaques were identified by MDCT. Six plaques were histopathologically classified as lipid rich (Stary III/IV), 6 plaques as intermediate (Stary V), and 5 plaques as calcific (Stary VII). Lipid-rich plaques had a mean density on MDCT of 42 +/- 22 Hounsfield units (HU), intermediate plaques had a mean density of 70 +/- 21 HU, and calcific plaques had a mean density of 715 +/- 328 HU. ANOVA analysis revealed a significant difference in plaque density between the 3 groups (P < 0.0001).

CONCLUSIONS

The comparison with histopathology confirms that tissue density as determined by contrast-enhanced MDCT might be used to differentiate atherosclerotic plaque morphology.

Synchronous gastrointestinal and musculoskeletal manifestations of different subtypes of inflammatory myofibroblastic tumor: CT, MRI and pathological features

We describe a case of an unusual multicentric appearance of an inflammatory myofibroblastic tumor, consisting of multiple gastrointestinal masses with different growth patterns and simultaneous, distant, musculoskeletal manifestations. CT and MR imaging features demonstrated a different degree of lesion enhancement, which proved histologically to be related to an alternation of predominantly spindle cell areas with a myxoid-vascular IMT subtype. A clear separation of the imaging characteristics of this tumor's subtypes by correlation with the pathology was not possible because of the mixed histologic character of the tumor in all its locations. However, MRI signal in the T2-weighted sequence was lower in the spindle cell variant localized predominantly in the musculoskeletal system, while the gastrointestinal predominantly myxoid-vascular counterparts showed slightly higher signal in the T2-weighted sequence.

Organ-Specific T Cell Receptor Repertoire in Target Organs of Murine Graft-Versus-Host After Transplantation Across Minor Histocompatibility Antigen Barriers

BACKGROUND

Minor histocompatibility antigens (miHags) are recognized by alloreactive cytotoxic donor T lymphocytes and trigger potent immune reactions such as graft-versus-host disease (GvHD) after major histocompatibility complex-matched transplantation. Our study focuses on tissue-specific T-cell responses to miHag-encoded peptides in GvHD target organs during the first 30 days in a murine transplant model.

METHODS

Complementarity determining region (CDR)3-size spectratyping was used to study T cell receptor (TCR) repertoires in recipient skin, liver, ileum, colon, spleen, and heart.

RESULTS

GvHD occurred as early as day 14 and was proven by histology in skin, liver, ileum, and colon. The heart was histologically not affected by GvHD but showed endomyocardial "quilty lesions." Two distinct patterns of TCR diversities could be identified. In skin, a restricted V beta usage in combination with all J beta segments contrasted with a complete V beta repertoire in intestinal organs combined with a restricted J beta usage. Interestingly, TCR repertoire in the heart was almost identical with intestinal CDR3-size patterns. Persisting clones were found in skin from day 9 to 30. In intestine and heart, identical sequences were obtained from several organs on day 14 and 21, but no persistence of CDR3 sequences could be observed.

CONCLUSIONS

These results suggest that in the skin a limited number of persisting T cell clones maintains GvHD, whereas in the intestine, temporary expansions of different clones may fuel the process of GvHD. Strategies that eliminate tissue-specific T cells on the basis of their activational status rather than their V beta expression but at the same time preserve a broad, overall TCR repertoire will help to increase the efficacy and safety of allogeneic stem cell transplantation.

Extensive peritoneal and omental lymphomatosis with raised CA 125 mimicking carcinomatosis: CT and intraoperative findings

Diffuse peritoneal and omental seeding are well-known forms of dissemination of metastatic carcinoma. A wide variety of primary neoplasms may cause peritoneal and omental carcinomatosis, most commonly carcinomas of the ovary, gastrointestinal tract and breast. Extensive involvement of the peritoneal cavity with lymphoma is, however, rare. The association of peritoneal lymphoma with a raised CA 125, a tumour marker which is commonly raised in ovarian carcinoma, is a highly challenging clinical situation, which to our knowledge has not been published before in the medical literature. Not being aware of the possibility of this unusual combination of clinical, laboratory and imaging findings can lead to an erroneous diagnosis, as in our case.

[18F]FLT PET for diagnosis and staging of thoracic tumours

The nucleoside analogue 3'-deoxy-3'-[18F]fluorothymidine (FLT) has been introduced for imaging of tumour cell proliferation by positron emission tomography (PET). This study evaluated the use of FLT in patients with thoracic tumours prior to treatment. Whole-body FLT PET was performed in 16 patients with 18 tumours [17 thoracic tumours (nine non-small cell lung cancers, five oesophageal carcinomas, two sarcomas, one Hodgkin's lymphoma) and one renal carcinoma] before treatment. Fluorine-18 fluorodeoxyglucose (FDG) PET was performed for comparison except in those patients with oesophageal carcinoma. For semi-quantitative analysis, the average and maximum standardised uptake values (avgSUV and maxSUV, respectively) (FLT, 114+/-20 min p.i.; FDG, 87+/-8 min p.i.; 50% isocontour region of interest) was calculated. All 17 thoracic tumours and 19/20 metastases revealed significant FLT accumulation, resulting in easy delineation from surrounding tissue. The additional small grade 1 renal carcinoma was not detected with either FLT or FDG. In most lung tumours (avgSUV 1.5-8.2) and metastases, FLT showed intense uptake. However, one of two spinal bone metastases was missed owing to the high physiological FLT uptake in the surrounding bone marrow. Oesophageal carcinoma primaries (avgSUV 2.7-10.0) and occasional metastases showed particularly favourable tumour/non-tumour contrast. Compared with FDG, tumour uptake of FLT was lower (avgSUV, P=0.0006; maxSUV, P=0.0001), with a significant linear correlation (avgSUV, r2=0.45; maxSUV, r2=0.49) between FLT and FDG. It is concluded that FLT PET accurately visualises thoracic tumour lesions. In the liver and the bone marrow, high physiological FLT uptake hampers detection of metastases. On the other hand, FLT may be favourable for imaging of brain metastases owing to the low physiological uptake.