Terbium-149 production: a focus on yield and quality improvement towards preclinical application.

Terbium-149 (T1/2 = 4.1 h, Eα = 3.98 MeV (16.7%), 28 µm range in tissue) is a radionuclide with potential for targeted alpha therapy. Due to the negligible emission of α-emitting daughter nuclides, toxicity to healthy tissue may be reduced in comparison with other α-particle emitters. In this study, terbium-149 was produced via 1.4 GeV proton irradiation of a tantalum target at the CERN-ISOLDE facility. The spallation products were mass separated and implanted on zinc-coated foils and, later, radiochemically processed. Terbium-149 was separated from the co-produced isobaric radioisotopes and the zinc coating from the implantation foil, using cation-exchange and extraction chromatographic techniques, respectively. At the end of separation, up to 260 MBq terbium-149 were obtained with > 99% radionuclidic purity. Radiolabeling experiments were performed with DOTATATE, achieving 50 MBq/nmol apparent molar activity with radiochemical purity > 99%. The chemical purity was determined by inductively coupled plasma-mass spectrometry measurements, which showed lead, copper, iron and zinc only at ppb level. The radiolabeling of the somatostatin analogue DOTATATE with [149Tb]TbCl3 and the subsequent in vivo PET/CT scans conducted in xenografted mice, showing good tumor uptake, further demonstrated product quality and its ability to be used in a preclinical setting.

Intrathoracic negative pressure therapy for pleural empyema using an open-pore drainage film.

BACKGROUND: We report our initial experience with intrathoracic negative pressure therapy (ITNPT) in the stage-adjusted treatment of pleural empyema (PE) based on a case series. MATERIALS AND METHODS: ITNPT represents a further development for intrathoracic use. After thoracic surgical open debridement, an intrathoracic negative pressure dressing was inserted. The drainage elements were a thin open-pore double-layer drainage film (OF) with open-pore polyurethane foams (PUF). Only the OF was placed in direct contact with the lung parenchyma. Negative pressure was generated using an electronic pump (continuous suction, -75 mm Hg). In revision thoracotomies, ITNPT was stopped or continued depending on local findings. RESULTS: In total, 31 patients with stage II and III pleural empyema underwent ITNPT, which was administered during the primary procedure (n = 17) or at revision (n = 14). Treatment duration was a mean of 10 days (2-18 days) with a mean change interval of 4 days (2-6 days). Intrathoracic negative pressure dressings were applied a mean of 3.5 (1-6) times. The empyema cavity continuously reduced in size and was cleansed by the suction. The OF has a minimum intrinsic volume with maximum absorption surface. Once negative pressure is established, there is no intrathoracic dead volume and the parenchyma can expand. The protective material properties of OF make ITNPT suitable for the treatment of pleural empyema. Targeted local intrathoracic drainage of the septic focus is a possible adjunct to surgery. The surgical dressings must be changed repeatedly. The method is suitable for the treatment of complex stage II and III pleural empyemas. CONCLUSION: The OF can be used as an intrathoracic drainage element for ITNPT in pleural empyema. This new application option expands the range of indications for negative pressure therapy.

Usage of a graph database for the selection of sterile items in the OR.

PURPOSE: In this work, we present a subsystem of a robotic circulating nurse, that produces recommendations for the next supplied sterile item based on incomplete requests from the sterile OR staff, the current situation, predefined knowledge and experience from previous surgeries. We describe a structure to store and query the underlying information in terms of entities and their relationships of varying strength. METHODS: For the implementation, the graph database Neo4j is used as a core component together with its querying language Cypher. We outline a specific structure of nodes and relationships, i.e., a graph. Primarily, it allows to represent entities like surgeons, surgery types and items, as well as their complex interconnectivity. In addition, it enables to match given situations and partial requests in the OR with corresponding subgraphs. The subgraphs provide suitable sterile items and allow to prioritize them according to their utilization frequency. RESULTS: The graph database was populated with existing data from 854 surgeries describing the intraoperative use of sterile items. A test scenario is evaluated in which a request for "Prolene" is made during a cholecystectomy. The software identifies a specific "Prolene" suture material as the most probable requested sterile item, because of its utilization frequency from over 95%. Other "Prolene" suture materials were used in less than 15% of the cholecystectomies. CONCLUSION: We have proposed a graph database for the selection of sterile items in the operating room. The example shows how the partial information from different sources can be easily integrated in a query, leading to an unique result. Eventually, we propose possible enhancements to further improve the quality of the recommendations. In the next step, the recommendations of the software will be evaluated in real time during surgeries.

Pyrocarbon interposition implant after lunate resection in Kienböck's disease: A case series.

In advanced stages of Kienböck's disease, the lunate is no longer conservable. One of the surgical options is to resect the lunate and replace it with a prosthesis. The procedure consisted in lunate resection and interposition of a free APSI® or Pi2® pyrocarbon implant through a dorsal approach. Follow-up was clinical and radiological on QuickDASH and PRWE scores. At a median follow-up of 3 years, 12 patients were reviewed, with a median age of 56 years. Flexion significantly decreased from 42° to 28° (p < 0.01). Extension and pronation-supination were conserved. Strength was 94% compared to the opposite side, with no significant difference from the preoperative measurement. Median QuickDASH and PRWE scores were 15.9 and 23.5 respectively and had significantly improved. One patient underwent scaphocapitate fusion because she was still in pain; the other patients were pain-free. No patients had to change jobs because of their wrist. Radiographically, there was no carpal collapse and carpal height was conserved. Radioscaphoid angle and ulnar translation were stable. There was 1 case of asymptomatic implant dislocation. Interposition of a pyrocarbon implant after lunate resection in advanced Kienböck's disease is a motion-conserving procedure that provides pain relief and functional recovery in the short and medium term. LEVEL OF EVIDENCE: IV.

Aspalathin alleviates skeletal muscle insulin resistance and mitochondrial dysfunction.

Natural compounds may bear promising therapeutic benefits against metabolic diseases such as type 2 diabetes mellitus (T2DM), which are characterized by a state of insulin resistance and mitochondrial dysfunction. Here, we examined the cellular mechanisms by which aspalathin, a dihydrochalcone C-glucoside unique to rooibos, may ameliorate palmitate-induced insulin resistance and mitochondrial dysfunction in cultured C2C12 myotubules. This current study demonstrated that aspalathin remains effective in improving glucose uptake in insulin-resistant skeletal muscle cells, supported by the upregulation of insulin-dependent signaling that involves the activation of insulin receptor (IR) and direct phosphorylation of protein kinase B (AKT). Interestingly, aspalathin also improved mitochondrial respiration and function, which was evident by an increased expression of carnitine palmitoyltransferase 1 (Cpt1), fatty acid transport protein 1 (Fatp1), sirtuin 1 (Sirt1), nuclear respiratory factor 1 (Nrf1), and transcription factor A, mitochondrial (Tfam). Importantly, our results showed that aspalathin treatment was effective in ameliorating the devastating outcomes of insulin resistance and mitochondrial dysfunction that are linked with an undesired pro-inflammatory response, by reducing the levels of well-known pro-inflammatory markers such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and protein kinase C-theta (PKC-theta). Thus, beyond improving glucose uptake and insulin signaling, the current study brings a new perspective in the therapeutic benefits of aspalathin in improving mitochondrial respiration and blocking inflammation to attenuate the detrimental effect of palmitate in skeletal muscle cells.

[Postoperative leaks in the gastrointestinal tract-diagnosis and treatment]. / Postoperative Leckagen im Gastrointestinaltrakt ­ Diagnostik und Therapie.

Postoperative leaks following esophageal, gastric, colonic or rectal resection represent a life-threatening complication that is associated with high morbidity and mortality. Leaks are generally diagnosed with a combination of the following: recognition of clinical deterioration, laboratory results, endoscopic and radiological imaging. In case of intraperitoneal leaks, surgery is mandatory. In case of mediastinal or retroperitoneal anastomotic insufficiencies, treatment mainly comprises interventional endoscopic procedures in an interdisciplinary approach. For endoscopic therapy, there are mainly two different methods described: closure of the defect with fully covered self-expandable stents with external drainage and closure of the defect with simultaneously internal drainage by endoscopic vacuum therapy.

Reconstruction of the distal radius using a double-barrel vascularized fibula flap: A case series.

Treatment of distal radius tumor sometimes requires sacrificing the epiphysis. We propose adding to currently available reconstruction options a technique using a double-barrel vascularized fibula flap fixed distally to the first carpal row, conserving midcarpal mobility. We monitored 4 cases of Campanacci III giant-cell tumor and 2 cases of osteosarcoma. After en-bloc tumor resection, a double-barrel vascularized fibula flap was lodged distally in the scaphoid and lunate and proximally in the radius. Follow-up was clinical and radiological, using DASH, PRWE and MSTS functional scores. At a median 3 years' follow-up, there were no cases of recurrence or non-union. Median ranges of motion were 23° flexion, 28° extension, 90° pronation and 62° supination. Median grip strength proportional to the contralateral side was 67%. Median DASH and PRWE functional scores were respectively 13.7 and 17 points. Median MSTS was 83%. Although this technique is challenging, with difficulties in double-barrel flap placement and in pedicle plication, the double-barrel vascularized fibula flap provided a stable and mobile wrist.

Cyclotron production and radiochemical purification of terbium-155 for SPECT imaging.

BACKGROUND: Terbium-155 [T1/2 = 5.32 d, Eγ = 87 keV (32%) 105 keV (25%)] is an interesting radionuclide suitable for single photon emission computed tomography (SPECT) imaging with potential application in the diagnosis of oncological disease. It shows similar decay characteristics to the clinically established indium-111 and would be a useful substitute for the diagnosis and prospective dosimetry with biomolecules that are afterwards labeled with therapeutic radiolanthanides and pseudo-radiolanthanides, such as lutetium-177 and yttrium-90. Moreover, terbium-155 could form part of the perfect "matched pair" with the therapeutic radionuclide terbium-161, making the concept of true radiotheragnostics a reality. The aim of this study was the investigation of the production of terbium-155 via the 155Gd(p,n)155Tb and 156Gd(p,2n)155Tb nuclear reactions and its subsequent purification, in order to obtain a final product in quantity and quality sufficient for preclinical application. The 156Gd(p,2n)155Tb nuclear reaction was performed with 72 MeV protons (degraded to ~ 23 MeV), while the 155Gd(p,n)155Tb reaction was degraded further to ~ 10 MeV, as well as performed at an 18 MeV medical cyclotron, to demonstrate its feasibility of production. RESULT: The 156Gd(p,2n)155Tb nuclear reaction demonstrated higher production yields of up to 1.7 GBq, however, lower radionuclidic purity when compared to the final product (~ 200 MBq) of the 155Gd(p,n)155Tb nuclear reaction. In particular, other radioisotopes of terbium were produced as side products. The radiochemical purification of terbium-155 from the target material was developed to provide up to 1.0 GBq product in a small volume (~ 1 mL 0.05 M HCl), suitable for radiolabeling purposes. The high chemical purity of terbium-155 was proven by radiolabeling experiments at molar activities up to 100 MBq/nmol. SPECT/CT experiments were performed in tumor-bearing mice using [155Tb]Tb-DOTATOC. CONCLUSION: This study demonstrated two possible production routes for high activities of terbium-155 using a cyclotron, indicating that the radionuclide is more accessible than the exclusive mass-separated method previously demonstrated. The developed radiochemical purification of terbium-155 from the target material yielded [155Tb]TbCl3 in high chemical purity. As a result, initial cell uptake investigations, as well as SPECT/CT in vivo studies with [155Tb]Tb-DOTATOC, were successfully performed, indicating that the chemical separation produced a product with suitable quality for preclinical studies.

Light quality and dormancy overcoming in seed germination of Echium plantagineum L. (Boraginaceae) / Qualidade da luz e superação de dormência na germinação de sementes de Echium plantagineum L. (Boraginaceae)

Abstract Light is considered a factor that influences the seed germination of many weed species, and it can signal whether the environmental conditions are favorable or are not favorable for germination. We aimed to study if there is an influence of light quality and dormancy overcoming in seed germination of Echium plantagineum L. We carried out a 2 x 6 factorial experiment, with and without dormancy overcoming with potassium nitrate followed by immersion in gibberellic acid; six light qualities, obtained through the light filters: blue, green, red, far-red, white light and absence of light. The evaluations performed were germination speed index (GSI), average germination time (AGT), germination at the four and 14 days after seeding (DAS), accumulated germination and relative frequency of germination. We observed significant interaction among the light qualities and seed dormancy overcoming or not for the studied variables. There was no significant effect of light qualities, in the evaluated variables, when performing dormancy overcoming, presenting germination above 90% in all the light qualities. However, without dormancy overcoming, we observed greater GSI, germination at four and 14 DAS for the red light filter with 5, 4, 29 and 45%, respectively. When the seeds were submitted to the absence of light, and without dormancy overcoming, there was only 7% of germination at 14 DAS. The seeds of E. plantagineum presented greater germination under incidence of red light, without dormancy overcoming, being classified as preferably positively photoblastics, provided that the dormancy is not overcome.

Resumo A luz é considerada um fator que influencia a germinação das sementes de muitas espécies de plantas daninhas, podendo sinalizar se as condições ambientais são favoráveis ou não para a germinação. Objetivou-se estudar se há influência da qualidade da luz e superação de dormência na germinação de sementes de Echium plantagineum L. Realizou-se um experimento fatorial 2 x 6, com e sem superação de dormência com nitrato de potássio seguido pela imersão em ácido giberélico; seis qualidades de luz, obtidas através de filtros de luz: azul, verde, vermelho, vermelho-distante, luz branca e ausência de luz. As avaliações realizadas foram índice de velocidade de germinação (IVG), tempo médio de germinação (TMG), germinação aos quatro e 14 dias após a semeadura (DAS), germinação acumulada e frequência relativa de germinação. Observou-se interação significativa entre as qualidades de luz e a superação ou não de dormência das sementes para as variáveis estudadas. Não houve efeito significativo das qualidades de luz, nas variáveis avaliadas, ao realizar superação de dormência, apresentando germinação acima de 90% em todas as qualidades de luz. Todavia, sem superação de dormência, observou-se maior IVG, germinação aos quatro e 14 DAS para o filtro de luz vermelha com 5,4, 29 e 45%, respectivamente. Quando as sementes foram submetidas à ausência de luz, e sem superação de dormência, houve apenas 7% de germinação aos 14 DAS. As sementes de E. plantagineum apresentam maior germinação sob incidência de luz vermelha, sem superação de dormência, sendo classificadas como fotoblásticas positivas preferenciais, desde que não seja superada a dormência.

Primary tumor side is associated with prognosis of colorectal cancer patients with brain metastases.

BACKGROUND: Brain metastases (BM) are a rare complication in colorectal cancer (CRC) patients and associated with an unfavorable survival prognosis. Primary tumor side (PTS) was shown to act as a prognostic and predictive biomarker in several trials including metastatic CRC (mCRC) patients. Here, we aim to investigate whether PTS is also associated with the outcome of CRC patients with BM. METHODS: Patients treated for CRC BM between 1988 and 2017 at an academic care center were included. Right-sided CRC was defined as located in the appendix, cecum and ascending colon and left-sided CRC was defined as located in the descending colon, sigma and rectum. RESULTS: Two hundred and eighty-one CRC BM patients were available for this analysis with 239/281 patients (85.1%) presenting with a left-sided and 42/281 patients (14.9%) with a right-sided primary CRC. BM-free survival (BMFS) was significantly longer in left-sided compared with right-sided CRC patients (33 versus 20 months, P = 0.009). Overall survival from CRC diagnosis as well as from diagnosis of BM was significantly longer in patients with a left-sided primary (42 versus 25 months, P = 0.002 and 5 versus 4 months, P = 0.005, respectively). In a multivariate analysis including graded prognostic assessment, PTS remained significantly associated with prognosis after BM (hazard ratio 0.65; 95% confidence interval: 0.46-0.92 months, P = 0.0016). CONCLUSIONS: PTS was associated with survival times after the rare event of BM development in CRC patients. Therefore, its prognostic value remains significant even thereafter.

Teaching breast ultrasound skills including core-needle biopsies on a phantom enhances undergraduate student's knowledge and learning satisfaction.

PURPOSE: To investigate whether a training program on breast ultrasound skills including core-needle biopsies to undergraduate students can improve medical knowledge and learning satisfaction. METHODS: Medical students attending mandatory classes at the Medical School of the University of Saarland received a supplemental theoretical and hands-on training program on ultrasound (US) breast screening and on US-guided core-needle biopsy using an agar-agar phantom. Experienced breast specialists and ultrasound examiners served as trainers applying Peyton's 4-step training approach. The students' theoretical knowledge and hands-on skills were tested before and after the training program, using a multiple-choice questionnaire (MCQ), the Objective Structured Clinical Examination (OSCE) and a student curriculum evaluation. RESULTS: The MCQ results showed a significant increase of the student's theoretical knowledge (50.2-75.2%, p < 0.001). After the course, the OSCE showed a mean total of 17.3/20 points (86.5%), confirming the practical implementation of the new skills. The student curriculum evaluation in general was very positive. A total of 16/20 questions were rated between 1.2 and 1.7 (very good) and 3 questions were rated as 2.1 (good). CONCLUSION: Undergraduate student's medical education can be enhanced by teaching breast US skills.

Biofunctionalization of 3D-printed silicone implants with immunomodulatory hydrogels for controlling the innate immune response: An in vivo model of tracheal defect repair.

The recent advances in 3D-printed silicone (PDMS: polydimethylsiloxane) implants present prospects for personalized implants with highly accurate anatomical conformity. However, a potential adverse effect, such as granuloma formation due to immune reactions, still exists. One potential way to overcome this problem is to control the implant/host interface using immunomodulatory coatings. In this study, a new cytokine cocktail composed of interleukin-10 and prostaglandin-E2 was designed to decrease adverse immune reactions and promote tissue integration by fixing macrophages into M2 pro-healing phenotype for an extended period of time. In vitro, the cytokine cocktail maintained low levels of pro-inflammatory cytokine (TNF-α and IL-6) secretions and induced the secretion of IL-10 and the upregulation of multifunctional scavenging and sorting receptor stabilin-1, expressed by M2 macrophages. This cocktail was then loaded in a gelatine-based hydrogel to develop an immunomodulatory material that could be used as a coating for medical devices. The efficacy of this coating was demonstrated in an in vivo rat model during the reconstruction of a tracheal defect by 3D-printed silicone implants. The coating was stable on the silicone implants for over 2 weeks, and the controlled release of the cocktail components was achieved for at least 14 days. In vivo, only 33% of the animals with bare silicone implants survived, whereas 100% of the animals survived with the implant equipped with the immunomodulatory hydrogel. The presence of the hydrogel and the cytokine cocktail diminished the thickness of the inflammatory tissue, the intensity of both acute and chronic inflammation, the overall fibroblastic reaction, the presence of oedema and the formation of fibrinoid (assessed by histology) and led to a 100% survival rate. At the systemic level, the presence of immunomodulatory hydrogels significantly decreased pro-inflammatory cytokines such as TNF-α, IFN-γ, CXCL1 and MCP-1 levels at day 7 and significantly decreased IL-1α, IL-1ß, CXCL1 and MCP-1 levels at day 21. The ability of this new immunomodulatory hydrogel to control the level of inflammation once applied to a 3D-printed silicone implant has been demonstrated. Such thin coatings can be applied to any implants or scaffolds used in tissue engineering to diminish the initial immune response, improve the integration and functionality of these materials and decrease potential complications related to their presence.

Impaired secretion of platelet granules in patients with Duchenne muscular dystrophy - results of a prospective diagnostic study.

A tendency to bleed during scoliosis surgery has been reported repeatedly in Duchenne muscular dystrophy (DMD) and diagnostic studies show a prolonged bleeding time. The pathophysiological background is still not fully understood. The short dystrophin isoform dp71 is expressed in platelets and mediates contractile properties. We performed a bicentric, non-blinded, prospective diagnostic study in 53 patients with confirmed DMD. Extensive laboratory analyses included platelet aggregometry and platelet flow cytometry, as well as routine coagulation analyses. Results of laboratory diagnostics were correlated with clinical data. Patients were subgrouped and analyzed according to ambulatory status and cardiac involvement. Platelet aggregation was reduced after stimulation with ADP (adenosine triphosphate) [60%; reference range 66-84%]. In addition, in the DMD cohort the expression of platelet activation markers CD62 and CD63 (flow cytometry analyses) was significantly lower than in healthy controls, most prominent in non-ambulatory patients with cardiac involvement. There was no clear association with the location of the underlying mutations in the dystrophin gene. No further abnormalities were identified regarding primary or secondary hemostasis. This study shows that platelets of patients with DMD have decreased expression of CD62 and CD63 which are markers for platelet granule release. This may indicate that patients with DMD have an impaired platelet granule secretion which may explain to some extent the increased bleeding, especially in mucocutaneous areas and perioperatively.

Maximum isometric tongue force in patients with obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnea (OSA) is a sleep disorder with a prevalence of 9-38%. The underlying pathology in OSA is a collapse of the upper airway. Especially in more severely affected patients, this collapse is often located at the level of the tongue base. Therefore, various implantable systems (anchors and ligament techniques) were developed to prevent or overcome this collapse. These systems are exposed to various forces. Different models have been developed to measure these forces and data comparing forces in healthy individuals with OSA patients are rare. PURPOSE: Purpose of the study was to evaluate possible differences in tongue forces between healthy individuals and patients with OSA. METHOD: To evaluate maximum isometric tongue forces, we conducted a matched pair design study including 20 healthy individuals and 20 patients suffering from OSA. Maximum isometric tongue forces were measured in an anterior/posterior direction with the help of self-designed new device that clamps the tongue. RESULTS: We could show that the maximum isometric force does not differ significantly in healthy individuals (10.7 ± 5.2N) from patients with OSA (14.4 ± 6.3N). CONCLUSION: Currently there are no indications that maximum isometric tongue force does differ in healthy individuals and patients with OSA. Higher, as well as lower, tongue forces in patients with OSA seem not to differ from healthy subjects and therefore may not be needed to consider, in the development of tongue management devices, for OSA patients.

Allogeneic expanded adipose-derived stem cells in the treatment of rectovaginal fistulas in Crohn's disease.

AIM: Crohn's disease (CD)-related rectovaginal fistulas (RVFs) are rare, challenging to treat and associated with a high morbidity. Due to a significant lack of data, we aimed to analyse the safety and feasibility of allogeneic adipose-derived stem cells (ASCs) in the treatment of CD-related RVF. METHOD: Four consecutive patients with CD-related RVF underwent treatment with expanded allogeneic ASCs extracted from a healthy donor in a tertiary referral centre in 2019. None of the patients had an intestinal diversion at the time of the treatment. Follow-up was performed 6 months postoperatively. RESULTS: The median operation time was 45 min with a median hospital stay of 3 days. No intra-operative complications occurred. Three patients (75%) developed recurrent RVF after a median follow-up of 19 days. Two patients required surgical treatment including loose seton drainage due to discharge and pain. One patient developed recurrence of symptoms after 10 days, but refused further surgical therapy. Only one patient (25%) showed healing of the RVF, with re-epithelialization of both the vaginal and rectal opening and absence of clinical symptoms. CONCLUSION: Expanded allogeneic ASC therapy represents a novel safe treatment option for CD-associated RVF. Although efficacy appears limited, further controlled studies are required to draw robust conclusions.

Chest CT target sign in a couple with COVID-19 pneumonia / Sinal do alvo na TC de tórax em um casal com pneumonia por COVID-19

Abstract We describe a target sign on chest CT characterized by a combination of peripheral ring-like opacity and a central nodular ground-glass opacity surrounding a vessel in a couple with COVID-19 pneumonia confirmed by real-time reverse transcriptase fluorescence polymerase chain reaction sputum analysis.

Resumo Descrevemos o sinal do alvo na TC de tórax representando combinação de opacidade com aspecto de anel periférico e componente central nodular em vidro fosco circundando estrutura vascular em um casal com COVID-19 confirmada por reação em cadeia da polimerase com transcrição reversa.

Establishment of a clinical SPECT/CT protocol for imaging of 161Tb.

BACKGROUND: It has been proposed, and preclinically demonstrated, that 161Tb is a better alternative to 177Lu for the treatment of small prostate cancer lesions due to its high emission of low-energy electrons. 161Tb also emits photons suitable for single-photon emission computed tomography (SPECT) imaging. This study aims to establish a SPECT protocol for 161Tb imaging in the clinic. MATERIALS AND METHODS: Optimal settings using various γ-camera collimators and energy windows were explored by imaging a Jaszczak phantom, including hollow-sphere inserts, filled with 161Tb. The collimators examined were extended low-energy general purpose (ELEGP), medium-energy general purpose (MEGP), and low-energy high resolution (LEHR), respectively. In addition, three ordered subset expectation maximization (OSEM) algorithms were investigated: attenuation-corrected OSEM (A-OSEM); attenuation and dual- or triple-energy window scatter-corrected OSEM (AS-OSEM); and attenuation, scatter, and collimator-detector response-corrected OSEM (ASC-OSEM), where the latter utilized Monte Carlo-based reconstruction. Uniformity corrections, using intrinsic and extrinsic correction maps, were also investigated. Image quality was assessed by estimated recovery coefficients (RC), noise, and signal-to-noise ratio (SNR). Sensitivity was determined using a circular flat phantom. RESULTS: The best RC and SNR were obtained at an energy window between 67.1 and 82.1 keV. Ring artifacts, caused by non-uniformity, were removed with extrinsic uniformity correction for the energy window between 67.1 and 82.1 keV, but not with intrinsic correction. Analyzing the lower energy window between 48.9 and 62.9 keV, the ring artifacts remained after uniformity corrections. The recovery was similar for the different collimators when using a specific OSEM reconstruction. Recovery and SNR were highest for ASC-OSEM, followed by AS-OSEM and A-OSEM. When using the optimized parameter setting, the resolution of 161Tb was higher than for 177Lu (8.4 ± 0.7 vs. 10.4 ± 0.6 mm, respectively). The sensitivities for 161Tb and 177Lu were 7.41 and 8.46 cps/MBq, respectively. CONCLUSION: SPECT with high resolution is feasible with 161Tb; however, extrinsic uniformity correction is recommended to avoid ring artifacts. The LEHR collimator was the best choice of the three tested to obtain a high-resolution image. Due to the complex emission spectrum of low-energy photons, window-based scatter correction had a minor impact on the image quality compared to using attenuation correction only. On the other hand, performing attenuation, scatter, and collimator-detector correction clearly improved image quality. Based on these data, SPECT-based dosimetry for 161Tb-labeled radiopharmaceuticals is feasible.