Metasurfaces with Asymmetric Optical Transfer Functions for Optical Signal Processing

Metasurface thin films created from arrays of structured optical elements have been shown to perform spatial filtering of optical signals. To extend their usefulness it is important that the symmetry of their response with changes to the in-plane wave vector k_{p}→-k_{p} can be tailored or even dynamically tuned. In this Letter we use a general theory of metasurfaces constructed from nondiffracting arrays of coupled metal particles to derive the optical transfer function and identify the physical properties essential for asymmetry. We validate our theory experimentally showing how the asymmetric response of a two-dimensional (planar) metasurface can be optically tuned. Our results set the direction for future developments of metasurfaces for optical signal processing.

Excitation of bound plasmons along nanoscale stripe waveguides: a comparison of end and grating coupling techniques

In this paper we excite bound long range stripe plasmon modes with a highly focused laser beam. We demonstrate highly confined plasmons propagating along a 50 µm long silver stripe 750 nm wide and 30 nm thick. Two excitation techniques were studied: focusing the laser spot onto the waveguide end and focusing the laser spot onto a silver grating. By comparing the intensity of the out-coupling photons at the end of the stripe for both grating and end excitation we are able to show that gratings provide an increase of a factor of two in the output intensity and thus out-coupling of plasmons excited by this technique are easier to detect. Authors expect that the outcome of this paper will prove beneficial for the development of passive nano-optical devices based on stripe waveguides, by providing insight into the different excitation techniques available and the advantages of each technique.

Kramers-Kronig-constrained variational dielectric fitting and the reflectance of a thin film on a substrate

A test was made of the ability of Kramers-Kronig-constrained variational dielectric fitting to extract the optical conductivity of a thin film from reflectance data containing structure due to both thin film and substrate. The reflectance of a series of well-characterized thin films of SrRu(x)Mg(1-x)O(3) and SrRu(x)O(3) with a variety of thicknesses (approximately 56-300 nm) and dc resistivities (approximately 250-2200 micro Omega cm) was measured. The low frequency values of the extracted optical conductivities agree with the dc measurements, however, removal of features due to the substrate improves with increasing film thickness.

Encysted spermatic cord hydroceles: a report of three cases in adults and a review of the literature

A hydrocele of the spermatic cord, which results from aberrant closure of the processus vaginalis, is an asymptomatic entity detected incidentally on computed tomography (CT)scans performed for other clinical indications. There are two variations of a spermatic cord hydrocele: the "encysted" variety that does not communicate with the peritoneal cavity, and the "funicular" variety that does communicate with the peritoneal cavity. The encysted type can be confused with an inguinal mass (lymphadenopathy, hernias), and also primary tumors of the cord. We reviewed CT scans for all three adults and ultrasound images for one patient. Confirmation of spermatic cord hydrocele was made by surgery in one case, and CT and follow-up CT in two cases. Our findings indicate that a mass of the spermatic cord, showing fluid attenuation by CT and an avascular,anechoic appearance with sound transmission by ultrasound in an otherwise asymptomatic patient or even in those with an underlying malignancy, should prompt the radiologist to consider the diagnosis of spermatic cord hydrocele. This may eliminate the need for unnecessary, highly invasive procedures such as biopsy or surgical exploration.

Geometric optics method for surface plasmon integrated circuits

A fully-analytic expression is derived for the phase of reflection of surface plasmons at a semi-infinite boundary. We apply this phase of reflection result in the geometric optics method to calculate the properties of surface plasmon stripe waveguides. Comprehensive vectorial numerical computations are compared with the analytic method to show that it is accurate. The loss of the surface plasmon stripe waveguide is calculated using the geometric optics approach, which is also found to be in close agreement with numerical computations. The geometric optics approach may be used to obtain accurate results for other surface plasmon structures, such as microdisk or ring resonators, with greater efficiency and physical intuition than numerical computation.

Case report: Calcifying fibrous pseudotumour of the adrenal gland

Calcifying fibrous pseudotumour is a distinct pathological entity usually occurring in the soft tissue of the extremities, trunk, axilla, pleura, mediastinum and peritoneum. This report describes the hitherto unreported occurrence of this tumour of the adrenal gland in a 10-year-old girl whose imaging findings closely resembled a neuroblastoma. This entity is a potential pitfall in diagnosing adrenal neuroblastoma.

Childhood cancers: hepatoblastoma

Hepatoblastoma is the most common primary liver tumor in children, accounting for just over 1% of pediatric cancers. The etiology is unknown, but it has been associated with Beckwith-Weidemann syndrome, familial adenomatosis polypi, and low birth weight. The primary treatment is surgical resection, however, chemotherapy plays an important role by increasing the number of tumors that are resectable. The prognosis for patients with resectable tumors is fairly good, however, the outcome for those with nonresectable or recurrent disease is poor.

Hepatocellular carcinoma and intrahepatic peripheral cholangiocarcinoma: enhancement patterns with quadruple phase helical CT--a comparative study

PURPOSE

To define the hemodynamic features of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma by using quadruple phase helical computed tomography (CT) and determine the value of this information in characterizing tumors.

MATERIALS AND METHODS

Helical CT of the liver was performed in 45 patients with newly diagnosed HCC or peripheral cholangiocarcinoma. Scans were obtained before and 25 seconds, 70 seconds, and 2-6 minutes after the start of the contrast material injection. The intensity and spatial distribution of contrast material uptake were evaluated during all phases. Time-attenuation curves were established for each lesion. Relative attenuation and lesion conspicuity were assessed. A diagnostic confidence level was assigned to each lesion.

RESULTS

In the majority of HCC lesions, a single, early peak of enhancement followed by a continuous decrease in tumor attenuation over time was seen. The greatest tumor conspicuity occurred during the delayed phase. In cholangiocarcinoma, tumor attenuation increased during the delayed phase. In the majority of lesions, the greatest tumor conspicuity was seen during the portal venous phase. In both tumor types, the diagnostic confidence level improved when the delayed phase was used.

CONCLUSION

The variation over time in the intensity of contrast enhancement in HCC and cholangiocarcinoma differs sufficiently to make this a useful diagnostic criterion. The delayed phase is particularly important because it amplifies this difference.

Thymic sarcoma in childhood

Sarcoma of the thymus is exceedingly rare, especially in children. We report a case of thymic sarcoma in a child, including the imaging findings which have not been previously described.

Osteosarcoma metastatic to the pancreas in young patients

Two rare cases of pancreatic metastases from osteosarcoma are reported. Metastatic spread occurred after treatment with chemotherapy. This unusual phenomenon represents an alternation in the natural history of osteosarcoma with increased long-term survival of patients who are successfully treated with chemotherapy.

Merkel cell carcinoma of the skin: imaging and clinical features in 93 cases

Clinical, pathological and imaging data for 93 patients with Merkel cell carcinoma were reviewed. Median survival duration from the date of diagnosis was estimated using the Kaplan-Meier product-limit method. Survival durations of patients with no metastastic disease, with regional lymph node metastasis only and with distant metastases were compared using the Cox-Mantel log-rank test. The median age for patients with Merkel cell carcinoma was 70 years (range 35-91 years). The tumour occurred in 71 men and 22 women. The most common primary site was the head and neck region (64 patients), followed by the extremities (21 patients) and the trunk (10 patients). Median survival duration for the whole group was 33 months (range 2-140 months). Imaging studies of the primary sites were available for 10 patients and of metastatic sites for seven patients. Sonograms of the primary skin lesions showed single or multicentric hypoechoic nodules arising from the dermis and growing into the subcutaneous tissues. CT scans showed single or multiple minimally enhancing soft tissue nodules, in two instances associated with lytic bone erosion. The metastatic lesions were moderately hypoechoic on sonography and target-shaped with or without ring-enhancement on CT. Imaging studies have a limited role in diagnosis of the clinically evident primary skin lesions, but may be helpful in the assessment of the depth of the invasion and are crucial in the evaluation of regional and distant metastatic disease. If regional adenopathy is found then CT of the chest, abdomen and pelvis may be in order.

Imaging of superficial soft-tissue infections: sonographic findings in cases of cellulitis and abscess

The variation in the sonographic appearances of superficial soft-tissue infections probably reflects a continuous process that leads from soft-tissue edema, seen in cellulitis, to a fully developed abscess and that depends on the type of infection or the immune status of the host. We describe the sonographic findings seen in this process and the variable appearance of abscesses, with emphasis on scanning techniques that facilitate the diagnosis of liquefaction.

Mesenchymal hamartoma of the chest wall in infants and children: a clinicopathological study of five patients

Mesenchymal hamartoma of chest-wall is a rare benign lesion that has varied histological characteristics and usually occurs during early infancy. We report the histological characteristics of mesenchymal hamartoma found in five patients aged respectively 25 days, 5 months, 8 months, and 4 and 8 years at presentation. Two patients presented with respiratory distress, two with an asymptomatic chest-wall mass, and one with a deformity of the left chest wall. Surgical resection was performed on four patients and a biopsy only in one patient. Overall, the tumors were well delineated, lobulated, tan to reddish in color, and on section showed blood-filled cystic spaces with interspersed small islands of cartilage and fibrous tissue. Histological analyses demonstrated mixtures of bone trabeculae with spindle-cell stroma, chondroblast-like proliferation, mature and immature hyaline cartilage, and aneurysmal bone cyst formation. All patients are alive and well without evidence of disease. Despite the alarming clinical and histologic presentation, mesenchymal hamartoma of the chest wall is a non-neoplastic benign lesion.

Sonography of the scrotum after orchiectomy: normal and abnormal findings

Sonography is the primary imaging technique for evaluating the scrotal contents. In this pictorial essay, we illustrate a range of normal and abnormal sonographic findings in patients after orchiectomy, including the appearances of the normal postorchiectomy space, acute and subacute hematomas, recurrent neoplasm, second primary tumor in the remaining testis, and testicular prostheses.

Cystic retroperitoneal lymphangioma: CT, ultrasound and MR findings

A case of cystic retroperitoneal lymphangioma complicated by hemorrhage is reported in a 7-year-old boy who presented with an abdominal mass. The mass which was partially obstructing the ureter was successfully resected. The imaging findings with emphasis on MR features are described.

Sonographic findings in Richter's hernia

Richter's hernia can present as a diagnostic challenge because of its usually small size and eccentric bowel wall involvement with limited luminal compromise. This article describes a case of Richter's hernia in the femoral canal and illustrates its sonographic features.

Malignant rhabdoid tumor of the kidney: imaging features in two cases

Two new cases of malignant rhabdoid tumor of the kidney (RTK) in childhood are reported. Both presented with large abdominal masses and developed hypertension and one became hypercalcemic during the course of the disease. In each case disseminated disease and death occurred within three months of diagnosis. The findings on imaging consisted of large renal masses with a central site of origin, distant metastases at the time of presentation, and a subcapsular fluid collection in one of the two patients. The clinical and imaging features of RTK may suggest this diagnosis when faced with a primary renal neoplasm in childhood.

The many faces of neuroblastoma

Neuroblastoma is a common tumor in childhood. It arises in the adrenal gland or in various extraadrenal primary sites of the sympathetic chain. Clinically, it may present as an abdominal mass or as disseminated metastatic disease. We studied 52 patients with neuroblastoma, and the typical and unusual radiographic features of the disease are presented.

Thyroid gland: US in patients with Hodgkin disease treated with radiation therapy in childhood

The authors retrospectively assessed with sonography the prevalence of thyroid gland abnormalities in 30 patients who underwent radiation therapy for Hodgkin disease between 1962 and 1984. Doses ranged from 3,000 to 4,500 rad (3,000-4,500 cGy). Abnormalities were found in the sonograms of 24 patients and included unilateral (n = 6) or bilateral (n = 2) atrophy; multiple hypoechoic lesions smaller than 0.75 cm (n = 18); and dominant cystic (n = 2), solid (n = 3), or complex lesions (n = 4) larger than 0.75 cm. The risk of development of an abnormality increased as the time from irradiation increased and was comparable between patients who did and did not receive chemotherapy as part of the treatment regimen. Although the pathologic correlates of the various abnormalities seen on sonograms may differ, the findings indicate a need for long-term follow-up of patients who underwent cervical irradiation for Hodgkin disease.

Osteosarcoma metastatic to the kidney

Two clinically silent renal metastatic lesions from primary osteogenic sarcoma were first detected on radionuclide bone scan. A needle biopsy performed under the guidance of abdominal ultrasonography confirmed the diagnosis. Prior to nephrectomy, further definition of the metastatic lesion was attained using enhanced computed tomography. A review of the English literature revealed only six previous cases of metastatic osteosarcoma detected in the kidney prior to autopsy.

Inflammatory metachronous hyperostosis of the clavicle and femur in children. Report of two cases, one with long-term follow-up

Two preteenage girls developed painful swelling of the left clavicle. This was followed by painful swelling of the femur, 7 months later in one girl and 8 years later in the other. Radiographic studies showed a predominantly sclerotic process in one patient and destruction associated with cortical thickening in the other. The patients received analgesic medications only, followed by gradual healing with cortical and medullary sclerosis. Long-term follow-up suggests that the condition is self-limited and that, with or without treatment, the bones eventually return to normal. Although the etiology of the lesions remains unknown, the radiographic features suggest an inflammatory reaction.

The growing teratoma syndrome: an unusual manifestation of treated, nonseminomatous germ cell tumors of the testis

Residual masses are a common finding after chemotherapy for retroperitoneal and other metastases from nonseminomatous germ cell tumors of the testis. These may contain mature teratoma, fibrotic tissue, or tumor. Mature teratoma, which is unresponsive to chemotherapy, may result from evolution of a malignant lesion during treatment, or it may represent a metastasis from a focus of mature teratoma in the primary testicular tumor. An enlarging retroperitoneal mass during the course of chemotherapy is usually due to treatment failure but rarely may be due to an enlarging mature teratoma, the so-called growing teratoma syndrome. This report concerns five patients with nonseminomatous germ cell tumors metastatic to the retroperitoneum in whom mature teratomas were found at surgery. These tumors had grown despite the administration of combination systemic chemotherapy, and the cystic component had increased in size. Three patients had evidence of urinary tract compression, three had vascular compression or displacement, and one had gastrointestinal compression. The retroperitoneal mass was excised in each patient, and all are alive 4-27 months after surgery without evidence of recurrence. Growing mature teratoma is unresponsive to chemotherapy but is cured by surgical excision. The possibility of the growing teratoma syndrome should be considered so that these lesions can be treated appropriately.

Computed tomography in histiocytosis X of the temporal bone

Involvement of the temporal bone in histiocytosis X is seen in about one-third of the cases at onset, is bilateral in 31% of cases, and is often clinically silent. We report two cases of histiocytosis X with temporal bone involvement and emphasize the usefulness of computed tomography in detecting such a lesion, noting its extraskeletal extension, and following the course of the disease.

Computed tomography of rectal and perirectal disease in AIDS patients

Twenty-eight homosexual men with Kaposi sarcoma as part of the acquired immune deficiency syndrome (AIDS-related KS) and 2 homosexual men without AIDS were examined with abdominal and pelvic computed tomography (CT). Abnormalities of the rectum and perirectal areas were seen in 8 of the 30 patients on CT examination. Endoscopy and biopsy of the colon in these 8 cases revealed inflammatory changes in 6 patients and KS in 2. The CT abnormalities were not specific for inflammatory disease or tumor, and endoscopy with biopsy was necessary to establish an accurate diagnosis.

Pathologic fracture in osteosarcoma. Impact of chemotherapy on primary tumor and survival

Twenty patients with osteosarcoma and pathologic fractures were treated with a chemotherapeutic regimen consisting of cis-diamminedichloroplatinum-II (CDP), Adriamycin (ADR) (doxorubicin) and high-dose methotrexate with citrovorum factor "rescue" (MTX-CF). Before the introduction of the regimen, the primary tumor in two patients was treated by immediate amputation and in 13 with preoperative intra-arterial CDP. Among these 13 patients, responses (healing) were observed in 11 (one required the addition of radiation therapy). In three patients, the responses were so dramatic that, at their request, surgery was deferred and treatment exclusively with chemotherapy was instituted. Based on this experience, treatment exclusively with chemotherapy was also administered to an additional five patients who were admitted without pathologic fractures. In the course of such treatment, pathologic fractures also developed; notwithstanding, chemotherapy was maintained and healing also occurred. One of the 20 patients had pulmonary metastases at diagnosis; these were resected after treatment and pathologic examination revealed no evidence of viable tumor. The remaining 19 patients were free of pulmonary metastases but these later developed in seven patients. These data were compared to a historical control series in which 16 of 21 patients with pathologic fractures developed pulmonary metastases. Three of the chemotherapy treated patients died of nonosteosarcoma related causes (leukemia, generalized varicella, and a metabolic complication). Overall, survival was improved in the chemotherapy treated patients as compared to the historical control series: 10 of 20 versus 6 of 21, respectively. Pathologic fractures in osteosarcoma may heal under treatment with chemotherapy, which also has a favorable impact on the eradication of pulmonary metastases and survival.

Massive Wilms' tumor: sonographic demonstration of therapeutic response without alteration in size

The use of ultrasound to detect a response of massive Wilms' tumor to preoperative chemotherapy is demonstrated. Anechoic areas appearing during treatment are highly suggestive of response even in the absence of a reduction in size.

Cavitation of a mediastinal mass following chemotherapy for histiocytosis-X: CT demonstration

A recurrent mediastinal mass, believed to be thymus, in an infant with classic idiopathic histiocytosis-X underwent massive cavitation following chemotherapy. Both the mass and cavitation resolved. The exact nature of development of air inside the mass is not known but communication with the airways or airspaces of the lungs is suspected.

Control of primary osteosarcoma with chemotherapy

High-dose methotrexate with citrovorum factor "rescue" (MTX-CF) produced an apparent complete response of the primary tumor in three patients with osteosarcoma. The response was sustained with MTX-CF, intra-arterial cis-diamminedichloroplatinum II (CDP) and Adriamycin (doxorubicin) for 18 months. Treatment was then electively discontinued. Local recurrence occurred in two patients, 6 and 4 months later, respectively. MTX-CF was reinstated and a complete response was again achieved in one patient. This has been maintained for 15+ months with MTX-CF and intra-arterial CDP administered for 13 of the 15+ months. Reinduction with MTX-CF failed in the second relapsed patient but an apparent remission was again achieved with radiation and intra-arterial CDP. This has been maintained with intravenous CDP, cyclophosphamide and phenylalanine mustard for 14+ months. A complete response in the primary tumor was still present in the nonrelapsed patient, 42 months from diagnosis. All patients have remained free of pulmonary metastases, 40+ to 42+ months from diagnosis.

Chemotherapy of locally aggressive head and neck tumors in the pediatric age group. Desmoid fibromatosis and nasopharyngeal angiofibroma

Our experience with the use of systemic chemotherapy in the management of locally aggressive head and neck tumors in the pediatric age group (desmoid fibromatosis and nasopharyngeal angiofibroma) is presented. Objective decreases in the size of tumors was found in all patients with desmoid fibromatosis was treated with chemotherapy before definitive surgical resection was performed. The changes noticed on examination correlated with the histologic and radiologic findings. Two patients with recurrent juvenile nasopharyngeal angiofibromas showed striking therapeutic improvement in their residual tumor mass as witnessed by radiographic studies and biopsies. Toxicity and side effects of the treatment are discussed.

Primary infantile hyperparathyroidism: clinical, laboratory, and radiographic features in 21 cases

Two cases of primary infantile hyperparathyroidism (PIH) are reported. In both cases the diagnosis was initially suspected from chest radiographs which were obtained to assess the etiology of fever and respiratory distress in one case and heart murmur in another. The first case responded well to subtotal parathyroidectomy. The second case had many unique features. (1) She never became overtly symptomatic. (2) She displayed a constellation of findings that are not yet emphasized. (3) Her indisputable radiographic findings of hyperparathyroidism vanished spontaneously by two months of age, whereas her biochemical alteration have persisted up to now, 2 1/2 years after birth. (4) There members of her family have subclinical hyperparathyroidism (elevated serum parathormone, hypercalcemia, and hypophosphatemia). Our review of 19 more cases showed that PIH has no specific clinical symptoms and/or signs. Of the laboratory findings, hypercalcemia was most consistently encountered. The radiographic findings, although not identical to those described in hyperparathyroid adults, had the greatest diagnostic specificity. The disorder carried a grave prognosis if not diagnosed promptly and managed surgically.

Intraarterial management of giant-cell tumors of the spine in children

Transcatheter arterial management of giant cell tumors of the spine was performed in two female patients aged 12 and 15 who had failed to respond to conventional therapy. Response was determined clinically by alleviation of pain and radiographically by regression and/or calcification of the tumor. Minor side effects included transient nausea, elevated body temperature, and pain.

Technical note. Use of CT in the placement of heat monitoring thermocouples for hyperthermia therapy

In 12 cancer patients undergoing hyperthermia therapy, computed tomography (CT) was used for placement of thermocouples within the tumoral tissue. Tumors were located in the thorax, abdomen, and pelvis. Computed tomography provided accurate angulation of the introduction angiocatheter as well as the ability to choose the shortest and safest path. The cross-sectional display was especially helpful in placing the heat monitoring thermocouple within the active part of the tumor rather than a necrotic portion. It is our opinion that CT is superior to fluoroscopy in this regard.

Acroosteolysis. Problems of diagnosis--report of four cases

Four cases of idiopathic acroosteolysis are reported. The first is a common phalangeal type, the second, the Hozay variety. The third case was diagnosed after a mumps infection, and marked regress of the changes was noted in the following years. The fourth case shows skin changes, periostitis, mild osteosclerosis, and skull changes as well as acroosteolysis.